context
stringlengths 545
71.9k
| questionsrc
stringlengths 16
10.2k
| question
stringlengths 11
563
|
|---|---|---|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia .
|
do men have anemia more or women ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ?
|
as a nurse , what manifestation do you expect from a patient with b12 deficiency ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest .
|
how big is each red blood cell ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ?
|
and how does sickle cell get to you ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ?
|
in the second paragraph in consider the following what are the symptoms of thickening blood ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event .
|
or does one side of your face droop ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements .
|
what is the cause of the strange cravings ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen .
|
given that jak2 is involved in a lot of myleoprolific disorders , are there available genetic mechanisms in the pipeline for correcting jak2 abnormalities ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood .
|
can anemia completely go away , or is it like diabetus , just with red blood cells ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia .
|
how many of the anemia patients in the united states survived in 2015 , and how many died ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia .
|
is normochromic normocytic a type of anemia ?
|
what is anemia anemia means that you have too few red blood cells ( rbcs ) or hemoglobin protein ( hgb ) in your blood . it can also mean that the hematocrit level is low in your blood . remember , red blood cells are each full of hemoglobin , and hemoglobin is the protein that transports oxygen from the lungs to the cells . hematocrit is the percentage of red blood cells in your blood versus the other components in the blood ( plasma ) . below are the normal levels of red blood cells , hemoglobin , and hematocrit in men and women . keep in mind that these normal ranges can vary based on age , altitude , and so on . lab results lower than these values suggest that a person has anemia . | | males | females | | red blood cells ( rbc ) | 4.7 to 6.1 million cells/mcl | 4.2 to 5.4 million cells/mcl | | hemoglobin ( hgb ) | 13.8 to 18.0 g/dl ( 8.6 to 11.2 mmol/l ) | 12.1 to 15.1 g/dl ( 7.5 to 9.4 mmol/l ) | | hematocrit ( hct ) | 42 - 52 % | 37 - 46 % | now take a moment and think about the fact that 5 million red blood cells ( average between genders ) get packed into a single microliter ( mcl ) ( 1/1000 of a milliliter ) . it 's hard to think about so many red blood cells in such a small space . what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ? you can think of a red blood cell as a box holding hemoglobin molecules . each hemoglobin molecule has two parts , called `` heme '' and '' globin '' . globin is a protein , which is like bricks and mortar for a house ; it provides structure . the heme is a disk within the globin protein that holds a single atom of iron in its center . in fact , iron is what makes blood the color red when it 's around oxygen , just like how iron will rust ( also red ! ) in the presence of oxygen . each heme can attach to 1 molecule of oxygen and each globin holds exactly 4 hemes . this means one hemoglobin molecule holds 4 oxygen and 250 million hemoglobin molecules can be found within each red blood cell . that 's a lot of oxygen ! if you don ’ t have enough red blood cells and/or hemoglobin , then your body won ’ t be able to effectively transport oxygen . check out `` what is anemia ? '' for a quick overview . what are the symptoms of anemia ? anemia means that you don ’ t have enough red blood cells and/or hemoglobin to effectively transport oxygen around the body ; all of the symptoms relate back to this problem . oxygen does n't get delivered effectively to the brain , muscles , and skin leading to some common symptoms like fatigue , poor concentration , weakness , and pale skin ( called pallor ) . these symptoms are common for all anemias . on the other hand , some symptoms are specific to the underlying cause of anemia : hemolytic anemias are a group of diseases in which the red blood cells are destroyed prematurely . when hemoglobin within red blood cells is broken down , the center rings of the protein ( called heme ) are converted into bilirubin . we usually get rid of bilirubin through urine/stool , but if there is too much of it floating around , then it can build up in the body and cause the skin to turn yellow ( aka . jaundice ) . in iron-defiency anemia , the body is not able to make hemoglobin effectively since each heme contains a bit of iron within it . patients lacking iron sometimes get the strange urge to eat things like dirt , sand , or ice as a result . in pregnant women , the blood gets diluted as blood volume goes up but the number of red blood cells stay the same . this form of `` dilutional anemia '' is common , and the increased blood volume can cause heart palpitations ( that feeling of your heart skipping a beat ) . patients with sickle cell anemia have red blood cells that are deformed and do n't sail smoothly through blood vessels . when these red blood cells clog up blood vessels it can lead to intense pain in the bones or chest . what causes anemia ? there are a lot of diseases and conditions which can lead to anemia . these diseases can be grouped together into four broad causes of having too few red blood cells ( rbcs ) in blood . | causes | associated diseases | | decreased production of rbcs | aplastic anemia folic acid deficiency iron deficiency anemia kidney disease leukemia and myelodysplastic syndrome thalassemia pernicious anemia ( vitamin b12 deficiency ) chronic diseases ( e.g . hiv , crohn 's disease , etc ... ) | | increased destruction of rbcs | glucose-6-phosphate dehydrogenase deficiency hemolytic anemia sickle cell anemia transfusion reactions | | loss of rbcs ( bleeding ) | gastrointestinal ulcers major injuries or surgery menstruation | | dilution of rbcs ( fluid overload ) | pregnancy | how likely are you to get anemia ? anemia is the most common blood disorder affecting 1.6 billion people ( 1 in 4 ) , with young children and pregnant women most at risk . the likelihood you could develop anemia depends on the underlying cause of the anemia . for example : iron deficiency anemia makes up for half of all anemias globally and is more common in women due to their menstrual cycle . sickle cell anemia affects 1 in 100 people in africa , but 1 in 3000 in the united states . this is because sickle cell anemia is a genetic disease found in people of african heritage . vegetarians/vegans , pregnant mothers , and alcoholics have an increased risk for nutrient deficiency anemias : vegetarians/vegans have an increased risk for iron deficiency anemia and vitamin b12 deficiency anemias because animal products contain these nutrients . pregnant women have increased iron and vitamin needs to help their fetus grow and are at an increased risk for iron , folate , and vitamin b12 deficiencies . alcohol impairs the ability of the liver to metabolize folate leading to folate deficiency anemia in alcoholics . how can you prevent anemia ? anemias caused by a deficiency of iron , folate , and vitamin b12 are easy to prevent with the use of vitamin supplements and a healthy diet . other anemias such as sickle cell are genetic and can not be prevented . how do you treat anemia ? anemia is treated by resolving the underlying cause of the anemia . patients with anemia from sudden blood loss may be given a blood transfusion , and patients with low iron or folate levels will be given vitamin and mineral supplements . additional medications may be given to treat the disease itself , such as steroids to depress the immune system for hemolytic anemia . consider the following : you may have noticed that men have more red blood cells and hemoglobin in a given volume of blood than women . why do you think that might be ? scientists are not sure yet , but one hypothesis is that higher testosterone levels in men stimulates red blood cell production . some athletes have been found `` blood doping '' , by using products like the hormone erythropoietin before a major event . why would they do that ? one reason is that erythropoietin ( normally made in the kidney ) is a hormone that helps to boost the production of rbc 's . injecting extra erythropoietin means that more rbc 's are made , which means more oxygen is carried to muscles with each heart beat during the event . blood doping is considered cheating in most sports , and it's dangerous to the athlete because rapidly getting too many rbcs increases the thickness of blood , which can lead to heart failure and stroke !
|
what if we had a speck of blood 2 microliters ( mcl ) in volume ? how many red blood cells would be in that speck of blood ? what 's inside blood ?
|
if so , would this type of anemia present with normal haemoglobin levels in the red blood cells but a reduction in the amount of blood cells per m/ul ?
|
what are global modernisms ? you might be wondering why this topic is called global modernisms , as if there is more than just one type of modernism in the history of art . when we talk about art history , it 's easy to look at that art through the lens of where we live and come from–and in this case , a great deal of that history has been written from the perspective of art historians and specialists living in europe and north america . what 's important to remember is that there are , in fact , many_different_ modernisms that have sprung up in all different places around the world–and not just in what we call `` the west . '' regions like africa , latin america , asia , and the middle east have seen their own artistic responses to modernity , and while some of them might share themes and visual qualities with western art , others have taken radical new paths . there are many different voices in art history , and museums like tate are striving to make them heard as exhibitions develop and collections grow . and while you wo n't find the whole history here , you can begin by getting to know these modern and contemporary artists , taking a look at their work , and hearing their stories . global modernisms : africa while artists like lucian freud were flourishing in '50s london , ibrahim el-salahi was pioneering a distinctly african modernism . having studied in london , el-salahi returned to his native sudan and forged a visual vocabulary by fusing his own experience of islamic , african , arab and western artistic traditions . in 1975 , el-salahi was wrongfully imprisoned by the sudanese government for six harrowing months , and this period as a political prisoner deeply informed the artist 's relationship to spirituality and trauma . using the ochre–or deep yellow–colour of the sudanese earth in his paintings , el-salahi has maintained strong links to his homeland while experimenting with modern forms . while staying rooted , he stands as a global example by using his art to address , as he says , '' your self , the people of your own culture , family , and neighbourhood , and [ finally ] all human beings , wherever they might be . '' only recently has this major figure in african modernism been brought into a more global art history through the efforts of major exhibitions . in terms of contemporary art , many african artists have followed el-salahi 's lead by making works that speak to their own experience as well as a global audience . meschac gaba , for example , draws his greatest inspiration from his hometown of cotonou , benin , in west africa , but uses this african city as a workspace for posing questions about global contemporary art . his museum of contemporary african art in london ( 2013 ) creates what he calls `` a new reality '' by staging an exhibition that speaks to his experience of africa set within the space of a european gallery . by doing so , he invites the western art establishment to engage with african art , but also to question why dedicated spaces like this do n't exist already . some artists , like south african william kentridge , investigate the big questions around colonialism through their art . in his animated film felix in exile , kentridge explores the relationship between a black woman and a white man through a dream-like lens . using charcoal drawings , kentridge tells the story of felix and nandi but also that of south africa 's violent and divided history . along with the other black figures in the story , nandi is tragically shot . her body and those of the others melt into the landscape , becoming hilly fields , ponds , and other geographic landmarks . what do you think kentridge is trying to say through these images ? is he trying to memorialise the dead , or is he telling us that this terrible history has become part of south african life and landscape ? meanwhile , american artist doug fishbone's elmina ( 2010 ) invites us to think about race and storytelling by inserting himself into a ghanaian film as the main character . as you 'll see in the contested terrains videos , artists like adolphus obara , michael macgarry , kader attia , and sammy baloji create a dialogue with western art history and theory through projections , collages , and photographs . obara and macgarry look at the fetishisation of objects and work to subvert those messages , putting them back into a global context . baloji creates collages of images from lubumbashi in the democratic republic of congo , creating parallels between the industrial heritage of that city and similar cities beyond africa . south african artist marlene dumas , on the other hand , explores issues of gender and sexuality in her paintings , as evident in her magdalena series . dumas uses nakedness to explore themes of love and fear , intimacy and distance . her female figures take on subtle male qualities , and vice versa , blurring boundaries and creating a real sense of vulnerability in her paintings . the name magdalena refers to the biblical figure of mary magdalene , a popular reference that viewers from different cultures could potentially understand . nicholas hlobo also tackles themes of sexuality and race , but in this case through the materials and language he uses . by utilising techniques traditionally used by women in south africa such as stitching and weaving , like in the artwork below , he challenges gender-based assumptions . the artist layers references to the xhosa culture of south africa through his titles while using similarly charged materials . the old and punctured inner tubes of car tyres that he gathers from repair shops in johannesburg refer to the urban experience of life there . in this case , hlobo uses the abstract qualities of modernism to get us thinking about real issues around art in culture , in africa and beyond . © tate , 2015
|
his museum of contemporary african art in london ( 2013 ) creates what he calls `` a new reality '' by staging an exhibition that speaks to his experience of africa set within the space of a european gallery . by doing so , he invites the western art establishment to engage with african art , but also to question why dedicated spaces like this do n't exist already . some artists , like south african william kentridge , investigate the big questions around colonialism through their art .
|
is n't is already postmodernism then ?
|
what are global modernisms ? you might be wondering why this topic is called global modernisms , as if there is more than just one type of modernism in the history of art . when we talk about art history , it 's easy to look at that art through the lens of where we live and come from–and in this case , a great deal of that history has been written from the perspective of art historians and specialists living in europe and north america . what 's important to remember is that there are , in fact , many_different_ modernisms that have sprung up in all different places around the world–and not just in what we call `` the west . '' regions like africa , latin america , asia , and the middle east have seen their own artistic responses to modernity , and while some of them might share themes and visual qualities with western art , others have taken radical new paths . there are many different voices in art history , and museums like tate are striving to make them heard as exhibitions develop and collections grow . and while you wo n't find the whole history here , you can begin by getting to know these modern and contemporary artists , taking a look at their work , and hearing their stories . global modernisms : africa while artists like lucian freud were flourishing in '50s london , ibrahim el-salahi was pioneering a distinctly african modernism . having studied in london , el-salahi returned to his native sudan and forged a visual vocabulary by fusing his own experience of islamic , african , arab and western artistic traditions . in 1975 , el-salahi was wrongfully imprisoned by the sudanese government for six harrowing months , and this period as a political prisoner deeply informed the artist 's relationship to spirituality and trauma . using the ochre–or deep yellow–colour of the sudanese earth in his paintings , el-salahi has maintained strong links to his homeland while experimenting with modern forms . while staying rooted , he stands as a global example by using his art to address , as he says , '' your self , the people of your own culture , family , and neighbourhood , and [ finally ] all human beings , wherever they might be . '' only recently has this major figure in african modernism been brought into a more global art history through the efforts of major exhibitions . in terms of contemporary art , many african artists have followed el-salahi 's lead by making works that speak to their own experience as well as a global audience . meschac gaba , for example , draws his greatest inspiration from his hometown of cotonou , benin , in west africa , but uses this african city as a workspace for posing questions about global contemporary art . his museum of contemporary african art in london ( 2013 ) creates what he calls `` a new reality '' by staging an exhibition that speaks to his experience of africa set within the space of a european gallery . by doing so , he invites the western art establishment to engage with african art , but also to question why dedicated spaces like this do n't exist already . some artists , like south african william kentridge , investigate the big questions around colonialism through their art . in his animated film felix in exile , kentridge explores the relationship between a black woman and a white man through a dream-like lens . using charcoal drawings , kentridge tells the story of felix and nandi but also that of south africa 's violent and divided history . along with the other black figures in the story , nandi is tragically shot . her body and those of the others melt into the landscape , becoming hilly fields , ponds , and other geographic landmarks . what do you think kentridge is trying to say through these images ? is he trying to memorialise the dead , or is he telling us that this terrible history has become part of south african life and landscape ? meanwhile , american artist doug fishbone's elmina ( 2010 ) invites us to think about race and storytelling by inserting himself into a ghanaian film as the main character . as you 'll see in the contested terrains videos , artists like adolphus obara , michael macgarry , kader attia , and sammy baloji create a dialogue with western art history and theory through projections , collages , and photographs . obara and macgarry look at the fetishisation of objects and work to subvert those messages , putting them back into a global context . baloji creates collages of images from lubumbashi in the democratic republic of congo , creating parallels between the industrial heritage of that city and similar cities beyond africa . south african artist marlene dumas , on the other hand , explores issues of gender and sexuality in her paintings , as evident in her magdalena series . dumas uses nakedness to explore themes of love and fear , intimacy and distance . her female figures take on subtle male qualities , and vice versa , blurring boundaries and creating a real sense of vulnerability in her paintings . the name magdalena refers to the biblical figure of mary magdalene , a popular reference that viewers from different cultures could potentially understand . nicholas hlobo also tackles themes of sexuality and race , but in this case through the materials and language he uses . by utilising techniques traditionally used by women in south africa such as stitching and weaving , like in the artwork below , he challenges gender-based assumptions . the artist layers references to the xhosa culture of south africa through his titles while using similarly charged materials . the old and punctured inner tubes of car tyres that he gathers from repair shops in johannesburg refer to the urban experience of life there . in this case , hlobo uses the abstract qualities of modernism to get us thinking about real issues around art in culture , in africa and beyond . © tate , 2015
|
what are global modernisms ? you might be wondering why this topic is called global modernisms , as if there is more than just one type of modernism in the history of art .
|
or global modernism has a different time frame ?
|
background curl in two dimensions line integrals in a vector field if you have n't already , you may also want to read `` why care about the formal definitions of divergence and curl '' for motivation . what we 're building to in two dimensions , curl is formally defined as the following limit of a line integral : $ \displaystyle \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) $ this is complicated , but it will make sense as we build up to it one piece at a time . formalizing fluid rotation suppose you have a flowing fluid whose velocity is given by a vector field $ \bluee { \textbf { f } } ( x , y ) $ , such as the one we looked at in the two-dimensional curl article . if you did n't already know about curl , but you did just learn about line integrals through a vector field , how would you measure fluid rotation in a region ? to take a relatively simple example , consider the vector field $ \begin { align } \bluee { \textbf { f } } ( x , y ) = \left [ \begin { array } { } -y \ x \end { array } \right ] \end { align } $ this is the quintessential counterclockwise rotation vector field . how can we make the idea of fluid rotation mathematical ( before knowing about curl ) ? one way to do this is to imagine walking around the perimeter of some region , like a unit circle centered at the origin , and measuring if the fluid seems to flow with you or against you at each point . concept check : let $ c $ represent the circumference of a unit circle centered at the origin , oriented counterclockwise . given the picture of the vector field $ \bluee { \textbf { f } } $ above , consider the following line integral : $ \begin { align } \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } \end { align } $ without calculating it , what is the sign of this integral ? ( recall that the symbol $ \displaystyle \oint $ just emphasizes the fact that the line integral is being done over a closed loop , but it 's computed the same way as any other line integral ) . more generally , if a fluid tends to flow counterclockwise around a region , you would expect that the line integral of that fluid 's velocity vector field around the perimeter of the region would be positive ( when it 's oriented counterclockwise ) . you could also imagine a more complicated vector field , in which the fluid flows with you at some points on your counterclockwise walk around the circle , but against you at others . the value $ \bluee { \textbf { f } } \cdot d\textbf { r } $ will be positive while the flow is with you , and negative when it 's against you . in a way , the integral $ \displaystyle \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } $ is like a voting system that counts up how much these different directions cancel each other out and which one wins overall . letting the size of the region change so , after mathematically expressing the idea of fluid rotation around a region , you might want to capture the more elusive idea of fluid rotation at a point . how might you go about that ? you could start by considering smaller and smaller regions around that point , such as circles of smaller and smaller radii , and seeing what the fluid flow around those regions looks like . concept check : back to our vector field $ \bluee { \textbf { f } } = \left [ \begin { array } { } -y \ x \end { array } \right ] $ , rather than just looking at the unit circle , let $ c_r $ represent a circle centered at the origin with radius $ r $ . this circle will still be oriented counterclockwise . compute the line integral of $ \bluee { \textbf { f } } $ around this circle as a function of $ r $ . how does this value relate to the circle $ c_r $ ? average rotation per unit area the answer to this last question suggests something interesting . the rotation around a region seems to be proportional to the area of that region . of course , you 've only shown this for circles centered at the origin , not all possible regions , but it is nevertheless suggestive . this might give you an idea . key idea : maybe if you take $ \displaystyle \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } $ , which measures the fluid flow around a region , and divide it by the area of that region , it can give you some notion of the average rotation per unit area . the idea of `` average rotation per unit area '' might feel a bit strange , but if you think back to the interpretation of curl , that 's kind of what we want curl to represent . rather than thinking about fluid rotation in a large region , curl is supposed to measure how fluid tends to rotate near a point . concept check : the vector field from the previous example is a little bit special in that the `` rotation-per-unit-area '' of circles around the origin is the same value for all circles . what is that value ? concept check : recall that the formula for $ \text { 2d-curl } $ is $ \begin { align } \text { 2d-curl } \ ; \bluee { \textbf { f } } = \dfrac { \partial f_2 } { \partial x } - \dfrac { \partial f_1 } { \partial y } \end { align } $ where $ f_1 $ and $ f_2 $ are the components of $ \bluee { \textbf { f } } $ . given the definition $ \begin { align } \bluee { \textbf { f } } ( x , y ) = \left [ \begin { array } { } -y \ x \end { array } \right ] \end { align } $ compute the curl of $ \bluee { \textbf { f } } $ . defining two-dimensional curl those last two questions show that the `` average rotation per unit area '' in circles centered at the origin happens to be the same as the curl of the function , at least for our specific example . this turns out to apply more broadly . in fact , the way we define the curl of a vector field $ \bluee { \textbf { f } } $ at a point $ ( x , y ) $ is to be the limit of this average rotation per unit area in smaller and smaller regions around the point $ ( x , y ) $ . specifically , ( drumroll please ) , here 's the formula defining two-dimensional curl : $ \begin { align } \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } \underbrace { \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) } _ { \text { average rotation per unit area } } \end { align } $ where $ \bluee { \textbf { f } } $ is a two-dimensional vector field . $ \golde { ( x , y ) } $ is some specific point in the plane . $ \rede { a } _ { \golde { ( x , y ) } } $ represents some region around the point $ \golde { ( x , y ) } $ . for instance , a circle centered at $ \golde { ( x , y ) } $ . $ |\rede { a } { \golde { ( x , y ) } } | $ indicates the area of $ \rede { a } { \golde { ( x , y ) } } $ . $ \displaystyle \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } $ indicates we are considering the limit as the area of $ \rede { a } { \golde { ( x , y ) } } $ goes to $ 0 $ , meaning this region is shrinking around $ \golde { ( x , y ) } $ . $ \redd { c } $ is the boundary of $ \rede { a } _ { \golde { ( x , y ) } } $ , oriented counterclockwise . $ \displaystyle \oint_\redd { c } $ is the line integral around $ \redd { c } $ , written as $ \oint $ instead of $ \int $ to emphasize that $ \redd { c } $ is a closed curve . this formula is impractical for computation , but the connection between this and fluid rotation is very clear once you wrap your mind around it . it is a very beautiful fact that this definition gives the same thing as the formula used to compute two-dimensional curl . $ \begin { align } \text { 2d-curl } \ ; \bluee { \textbf { f } } = \dfrac { \partial f_2 } { \partial x } - \dfrac { \partial f_1 } { \partial y } \end { align } $ one more feature of conservative vector fields background : conservative vector fields if $ \bluee { \textbf { f } } ( x , y ) $ is a conservative vector field , all line integrals over closed loops are $ 0 $ . looking at the integral above , what does this imply ? this gives an important fact : if a vector field is conservative , it is irrotational , meaning the curl is zero everywhere . in particular , since gradient fields are always conservative , the curl of the gradient is always zero . that is a fact you could find just by chugging through the formulas . however , i think it gives much more insight to understand it using the definition of curl together with the intuition for why gradient fields are conservative . what about the converse ? if a vector field has zero curl everywhere , does that mean it must be conservative ? summary if a vector field represents fluid flow , you can quantify `` fluid rotation in a region '' by taking the line integral of that vector field along the border of that region . to go from the idea of fluid rotation in a region to fluid flow around a point ( which is what curl measures ) , we introduce the idea of `` average rotation per unit area '' in a region . then consider what this value approaches as your region shrinks around a point . in formulas , this gives us the definition of two-dimensional curl as follows : $ \displaystyle \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { \rede { a } { \golde { ( x , y ) } } \to 0 } \underbrace { \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) } _ { \text { average rotation per unit area } } $ this relationship between curl and closed-loop line integrals implies that irrotational fields and conservative fields are one and the same .
|
background curl in two dimensions line integrals in a vector field if you have n't already , you may also want to read `` why care about the formal definitions of divergence and curl '' for motivation . what we 're building to in two dimensions , curl is formally defined as the following limit of a line integral : $ \displaystyle \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) $ this is complicated , but it will make sense as we build up to it one piece at a time .
|
which is used to interpret divergence and curl ?
|
background curl in two dimensions line integrals in a vector field if you have n't already , you may also want to read `` why care about the formal definitions of divergence and curl '' for motivation . what we 're building to in two dimensions , curl is formally defined as the following limit of a line integral : $ \displaystyle \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) $ this is complicated , but it will make sense as we build up to it one piece at a time . formalizing fluid rotation suppose you have a flowing fluid whose velocity is given by a vector field $ \bluee { \textbf { f } } ( x , y ) $ , such as the one we looked at in the two-dimensional curl article . if you did n't already know about curl , but you did just learn about line integrals through a vector field , how would you measure fluid rotation in a region ? to take a relatively simple example , consider the vector field $ \begin { align } \bluee { \textbf { f } } ( x , y ) = \left [ \begin { array } { } -y \ x \end { array } \right ] \end { align } $ this is the quintessential counterclockwise rotation vector field . how can we make the idea of fluid rotation mathematical ( before knowing about curl ) ? one way to do this is to imagine walking around the perimeter of some region , like a unit circle centered at the origin , and measuring if the fluid seems to flow with you or against you at each point . concept check : let $ c $ represent the circumference of a unit circle centered at the origin , oriented counterclockwise . given the picture of the vector field $ \bluee { \textbf { f } } $ above , consider the following line integral : $ \begin { align } \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } \end { align } $ without calculating it , what is the sign of this integral ? ( recall that the symbol $ \displaystyle \oint $ just emphasizes the fact that the line integral is being done over a closed loop , but it 's computed the same way as any other line integral ) . more generally , if a fluid tends to flow counterclockwise around a region , you would expect that the line integral of that fluid 's velocity vector field around the perimeter of the region would be positive ( when it 's oriented counterclockwise ) . you could also imagine a more complicated vector field , in which the fluid flows with you at some points on your counterclockwise walk around the circle , but against you at others . the value $ \bluee { \textbf { f } } \cdot d\textbf { r } $ will be positive while the flow is with you , and negative when it 's against you . in a way , the integral $ \displaystyle \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } $ is like a voting system that counts up how much these different directions cancel each other out and which one wins overall . letting the size of the region change so , after mathematically expressing the idea of fluid rotation around a region , you might want to capture the more elusive idea of fluid rotation at a point . how might you go about that ? you could start by considering smaller and smaller regions around that point , such as circles of smaller and smaller radii , and seeing what the fluid flow around those regions looks like . concept check : back to our vector field $ \bluee { \textbf { f } } = \left [ \begin { array } { } -y \ x \end { array } \right ] $ , rather than just looking at the unit circle , let $ c_r $ represent a circle centered at the origin with radius $ r $ . this circle will still be oriented counterclockwise . compute the line integral of $ \bluee { \textbf { f } } $ around this circle as a function of $ r $ . how does this value relate to the circle $ c_r $ ? average rotation per unit area the answer to this last question suggests something interesting . the rotation around a region seems to be proportional to the area of that region . of course , you 've only shown this for circles centered at the origin , not all possible regions , but it is nevertheless suggestive . this might give you an idea . key idea : maybe if you take $ \displaystyle \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } $ , which measures the fluid flow around a region , and divide it by the area of that region , it can give you some notion of the average rotation per unit area . the idea of `` average rotation per unit area '' might feel a bit strange , but if you think back to the interpretation of curl , that 's kind of what we want curl to represent . rather than thinking about fluid rotation in a large region , curl is supposed to measure how fluid tends to rotate near a point . concept check : the vector field from the previous example is a little bit special in that the `` rotation-per-unit-area '' of circles around the origin is the same value for all circles . what is that value ? concept check : recall that the formula for $ \text { 2d-curl } $ is $ \begin { align } \text { 2d-curl } \ ; \bluee { \textbf { f } } = \dfrac { \partial f_2 } { \partial x } - \dfrac { \partial f_1 } { \partial y } \end { align } $ where $ f_1 $ and $ f_2 $ are the components of $ \bluee { \textbf { f } } $ . given the definition $ \begin { align } \bluee { \textbf { f } } ( x , y ) = \left [ \begin { array } { } -y \ x \end { array } \right ] \end { align } $ compute the curl of $ \bluee { \textbf { f } } $ . defining two-dimensional curl those last two questions show that the `` average rotation per unit area '' in circles centered at the origin happens to be the same as the curl of the function , at least for our specific example . this turns out to apply more broadly . in fact , the way we define the curl of a vector field $ \bluee { \textbf { f } } $ at a point $ ( x , y ) $ is to be the limit of this average rotation per unit area in smaller and smaller regions around the point $ ( x , y ) $ . specifically , ( drumroll please ) , here 's the formula defining two-dimensional curl : $ \begin { align } \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } \underbrace { \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) } _ { \text { average rotation per unit area } } \end { align } $ where $ \bluee { \textbf { f } } $ is a two-dimensional vector field . $ \golde { ( x , y ) } $ is some specific point in the plane . $ \rede { a } _ { \golde { ( x , y ) } } $ represents some region around the point $ \golde { ( x , y ) } $ . for instance , a circle centered at $ \golde { ( x , y ) } $ . $ |\rede { a } { \golde { ( x , y ) } } | $ indicates the area of $ \rede { a } { \golde { ( x , y ) } } $ . $ \displaystyle \lim_ { |\rede { a } { \golde { ( x , y ) } } | \to 0 } $ indicates we are considering the limit as the area of $ \rede { a } { \golde { ( x , y ) } } $ goes to $ 0 $ , meaning this region is shrinking around $ \golde { ( x , y ) } $ . $ \redd { c } $ is the boundary of $ \rede { a } _ { \golde { ( x , y ) } } $ , oriented counterclockwise . $ \displaystyle \oint_\redd { c } $ is the line integral around $ \redd { c } $ , written as $ \oint $ instead of $ \int $ to emphasize that $ \redd { c } $ is a closed curve . this formula is impractical for computation , but the connection between this and fluid rotation is very clear once you wrap your mind around it . it is a very beautiful fact that this definition gives the same thing as the formula used to compute two-dimensional curl . $ \begin { align } \text { 2d-curl } \ ; \bluee { \textbf { f } } = \dfrac { \partial f_2 } { \partial x } - \dfrac { \partial f_1 } { \partial y } \end { align } $ one more feature of conservative vector fields background : conservative vector fields if $ \bluee { \textbf { f } } ( x , y ) $ is a conservative vector field , all line integrals over closed loops are $ 0 $ . looking at the integral above , what does this imply ? this gives an important fact : if a vector field is conservative , it is irrotational , meaning the curl is zero everywhere . in particular , since gradient fields are always conservative , the curl of the gradient is always zero . that is a fact you could find just by chugging through the formulas . however , i think it gives much more insight to understand it using the definition of curl together with the intuition for why gradient fields are conservative . what about the converse ? if a vector field has zero curl everywhere , does that mean it must be conservative ? summary if a vector field represents fluid flow , you can quantify `` fluid rotation in a region '' by taking the line integral of that vector field along the border of that region . to go from the idea of fluid rotation in a region to fluid flow around a point ( which is what curl measures ) , we introduce the idea of `` average rotation per unit area '' in a region . then consider what this value approaches as your region shrinks around a point . in formulas , this gives us the definition of two-dimensional curl as follows : $ \displaystyle \text { 2d-curl } \ , \bluee { \textbf { f } } \golde { ( x , y ) } = \lim_ { \rede { a } { \golde { ( x , y ) } } \to 0 } \underbrace { \left ( \dfrac { 1 } { |\rede { a } { \golde { ( x , y ) } } | } \oint_\redd { c } \bluee { \textbf { f } } \cdot d\textbf { r } \right ) } _ { \text { average rotation per unit area } } $ this relationship between curl and closed-loop line integrals implies that irrotational fields and conservative fields are one and the same .
|
concept check : let $ c $ represent the circumference of a unit circle centered at the origin , oriented counterclockwise . given the picture of the vector field $ \bluee { \textbf { f } } $ above , consider the following line integral : $ \begin { align } \oint_c \bluee { \textbf { f } } \cdot d\textbf { r } \end { align } $ without calculating it , what is the sign of this integral ? ( recall that the symbol $ \displaystyle \oint $ just emphasizes the fact that the line integral is being done over a closed loop , but it 's computed the same way as any other line integral ) .
|
why the integral of f.dr is proportional to the area ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ?
|
what will happen , to the time period of a simple pendulum hung in a lift , that is accelerated downwards with an acceleration a > g ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ?
|
will it oscillate in a reversed manner , provided the top of the lift is open ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ?
|
i can not understand 3rd example : why probe path become diagonally ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon .
|
earth has a gravitational pull , so why moon is not on earth ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences .
|
while watching the astronauts eating in the iss , it got me thinking ... does gravity affect blood circulation ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences .
|
on the other hand the blood travelling through the veins and arteries are powered or made to move with the help of the heart , so does 0 - gravity affect the circulatory system ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
how to the astronauts eat in mid air there is no gravitational force pulling them down does n't that hurt their bodies when they come down ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
is dark matter considered as an external force ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon .
|
in free fall , when an object reaches terminal velocity , why does the force of drag ( air resistance ) become equal to the weight ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object .
|
why do internal forces not cause change in motion of a body ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
does the density of an object affect the acceleration when there is an external force ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon .
|
if it was a small little cube of gold , with the same mass of 1 kg , and i apply the same force , will that result in the same acceleration of the object ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences .
|
why do n't the satellites fall while orbiting around the earth ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object .
|
in the elevator problem , if the acceleration due to gravity is 9.8 n and the force applied is 10 n can the elevator accelerate ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example .
|
how to objects inside the iss experience free fall when there is air inside ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity .
|
on the 3rd question , if the 3rd law indicates that an object will keep going in a straight line , why does the probe not change its direction ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
i mean you could answer buy adding the vectors , but there are no vectors , the net force is zero , no ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others .
|
why is it called the law of inertia , and not just , newton 's laws of motion ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object .
|
why does internal forces within an object can not cause a change in that object 's overall motion ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object .
|
could someone please explain number 2 for me , i do n't get why the forces are equal since the elevator is going up , does n't the upward force have to be more ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others .
|
what has newton 's 1st law got to do with inertia ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia .
|
so since things with more mass are harder to accelerate does that mean that a pebble would fall faster than a boulder if dropped from the same height ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
in the lift example , should n't the fc force be greater than fg as the lift 's moving upwards ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ?
|
in the last paragraph , example 3 , i do not understand how the space probe moves in path c. can you please explain ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
b . the space probe would speed up . c. the space probe would slow down and eventually stop .
|
for example three , what would happen to the probe if the vertical thruster was on for a long time ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
another question i have is how much force is needed to cancel the horizontal force and go totally down and not diagnol ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition .
|
if the net forces acting on a box of burritos is zero , then it 's not accelerating , right ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
would you need to make up a force to account for that acceleration ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
what is the difference between net force and force ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
what is the difference between net force and force ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
if the net force is 0 , why does n't the object stay at rest ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
( regarding my previous question ) : so the net force does not include the initial force ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
in the second question , if the force exerted by cable is equal to force of gravity then how will the elevator move upwards ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force .
|
an object at rest stays at rests ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
in example 2 , if the elevator is moving upward , the force of cable has to be more than the gravitational force , otherwise the forces would balance out and the elevator would n't move , so is n't the answer a : fc is greater than fg ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion .
|
does free fall affect blood pressure , flow of blood , or peristalsis ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
my question is , what force makes the food float ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
if when there is no net force , objects maintain their velocity then which upward net force makes me stop falling when i hit the ground ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
for example 3 if the elevator is moving upwards , then should n't the upward force be greater ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ?
|
what happens to the burritos ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ?
|
in example 2 : elevator lift , how can the answer be that the forces are equal ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia .
|
what is the difference between mass and weight ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero .
|
why is c the correct answer and not b ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
b . the space probe would speed up . c. the space probe would slow down and eventually stop .
|
the statement says if an object is not accelerating i.e that it is stopped or moving at a constant speed , has no net forces acting on it which has to be false or else the object would n't have the constant speed would it ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the fact that there was a vertical force on the space probe does not affect the horizontal velocity '' why vertical force is not affecting on the horizontal velocity ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
b . the space probe would speed up . c. the space probe would slow down and eventually stop .
|
why would an object in space move horizontally ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero .
|
if an unbalanced force does n't act on an object moving at a constant velocity , would this object move forever ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
a . the space probe would continue with constant velocity . b .
|
however , if we were to be in interstellar space and i pushed an object forward , would n't that object keep moving in that same direction with a constant velocity ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
will the space probe keep moving , as the net force is 0 ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law .
|
if there is an elevator at rest in the international space station , how does that affect the scale a person is standing on inside that elevator ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
why the net force on the burritos was 15n , ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
we said that the net force is th addition of vectors , why did we substract ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so .
|
what is inerrtia , essentialy ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia .
|
does inertia mean the interaction with gigg 's field ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
so like in examples 1 & 3 , you need to ignore the force in example 2 that set the elevator in motion ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a .
|
in example 1 , what would happen if one of the forces was greater than the other ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ?
|
for example , if i 'm playing air hockey and the puck was moving initially in the vertical direction but then i hit it in the horizontal direction , the puck moves in the horizontal direction ( if i hit it hard enough ) right ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
for example 2 : elevator lift ..if this net force is zero is that the elevator is moving upward or not ..without force how can it be displaced ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others .
|
then the cell phone breaks into pieces after hitting ground and scatter away is this happening on basis of newton 's 1st law or law of inertia ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others .
|
when was newton 's first law of motion created the yea r ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others .
|
newton 's first law was also called ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ?
|
is the direction where the space probe moves in the last example actually the resultant of the two velocity vectors ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ?
|
what will happen , to the time period of a simple pendulum hung in a lift , that is accelerated downwards with an acceleration a > g ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ?
|
will it oscillate in a reversed manner , provided the top of the lift is open ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ?
|
in the 3rd example how is the probe getting pushed backwards ; how will newtons 3rd law work in deep space ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object .
|
so a measurement of force is always done as an instantaneous moment captured in time ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ?
|
how do space people survive in space ?
|
why do objects slow down ? before galileo and newton , many people thought objects slowed down because they had a natural built in tendency to do so . but those people were n't taking into account the many forces—e.g. , friction , gravity , and air resistance—here on earth that cause objects to change their velocity . if we could observe the motion of an object in deep interstellar space , we would be able to observe the natural tendencies of an object 's motion free from any external influences . in deep interstellar space , we would observe that if an object had a velocity , it would continue moving with that velocity until there was some force to cause a change in the motion . similarly , if an object were at rest in interstellar space , it would remain at rest until there was a force to cause it to change its motion . in the video below , we can see that objects in the international space station either remain at rest or continue with constant velocity relative to the space station until acted upon by a force . the idea that objects only change their velocity due to a force is encapsulated in newton 's first law . newton 's first law : an object at rest remains at rest , or if in motion , remains in motion at a constant velocity unless acted on by a net external force . note the repeated use of the verb remains . we can think of this law as preserving the status quo of motion . newton ’ s first law of motion states that there must be a cause—which is a net external force—for there to be any change in velocity , either a change in magnitude or direction . an object sliding across a table or floor slows down due to the net force of friction acting on the object . but on an air hockey table , where air keeps the puck from touching the table , the air hockey puck continues moving with a roughly constant velocity until a force acts on it—like when it bumps into the side of the table . what do force , external force , and net force mean ? a force is a push or a pull exerted on one object by another object . the units of force $ f $ are called newtons or simply $ \text { n } $ . an external force is a force originating from outside an object rather than a force internal to an object . for instance , the force of gravity that earth exerts on the moon is an external force on the moon . however , the force of gravity that the inner core of the moon exerts on the outer crust of the moon is an internal force on the moon . internal forces within an object ca n't cause a change in that object 's overall motion . the net force , written as $ \sigma f $ , on an object is the total force on an object . if many forces act on an object , then the net force is the sum of all the forces . but be careful—since force $ f $ is a vector , to find the net force $ \sigma f $ , the forces must be added up like vectors using vector addition . in other words , if a box of frozen burritos had a force of magnitude 45 newtons exerted on it to the right and a force of magnitude 30 newtons exerted on it to the left , the net force in the horizontal direction would be $ \sigma f_ { \text { horizontal } } =45\text { n } -30\text { n } $ $ \sigma f_ { \text { horizontal } } =15\text { n } $ assuming rightward is the positive direction . newton 's first law says that if the net force on an object is zero ( $ \sigma f=0 $ ) , then that object will have zero acceleration . that does n't necessarily mean the object is at rest , but it means that the velocity is constant . in other words , constant zero velocity—at rest—or constant non-zero velocity—moving with a constant velocity . for the box of frozen burritos , if the rightward force had a magnitude of 45 newtons and the leftward force had a magnitude of 45 newtons , the net force would be zero . the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia . newton ’ s first law is often called the law of inertia . as we know from experience , some objects have more inertia than others . it is obviously more difficult to change the motion of a large boulder than that of a basketball , for example . the inertia of an object is measured by its mass . mass can be determined by measuring how difficult an object is to accelerate . the more mass an object has , the harder it is to accelerate . also , roughly speaking , the more “ stuff ” —or matter—in something , the more mass it will have , and the harder it will be to change its velocity , i.e. , accelerate . what do solved questions involving newton 's first law look like ? example 1 : space probe drift a space probe is drifting to the right at a constant velocity in deep interstellar space—far from any influence due to planets and stars—with its rockets off . if two rocket thrusters both turn on simultaneously exerting identical forces leftward and rightward in the directions shown , what would happen to the motion of the rocket ? a . the space probe would continue with constant velocity . b . the space probe would speed up . c. the space probe would slow down and eventually stop . d. the space probe would immediately stop . the correct answer is a . according to newton 's first law , a non-zero net force is required to change the velocity of an object . the net force on the space probe is zero—since the forces on it cancel—so there is no change in the velocity of the probe . example 2 : elevator lift an elevator is being pulled upward at a constant velocity by a cable as seen in the diagram below . while the elevator is moving upward at constant velocity , how does the magnitude of the upward force exerted on the elevator by the cable— $ \redd { f_c } $ —compare to the magnitude of the downward force of gravity— $ \greend { f_g } $ —on the elevator ? a . $ \redd { f_c } $ is greater than $ \greend { f_g } $ . b . $ \redd { f_c } $ is equal to $ \greend { f_g } $ . c. $ \redd { f_c } $ is smaller than $ \greend { f_g } $ . d. $ \redd { f_c } $ could be larger or smaller than $ \greend { f_g } $ depending on the mass of the elevator . the correct answer is b . if the elevator is moving with constant velocity , the net force must be zero . in order for the net force on the elevator to be zero , the upward and downward forces must cancel exactly . example 3 : space probe path a space probe is drifting to the right with constant velocity in deep interstellar space—far from any influence due to planets and stars . if a rocket thruster turns on and then off for a short burst of force in the direction shown , what would best represent the path traveled by the rocket after the thruster turns off ? a . path a b . path b c. path c d. path d the correct answer is c. after the rocket thruster turns off , there will be no net force on the space probe . once the net force is zero , the velocity—both magnitude and direction—must be constant . because of newton 's first law , the space probe moves in a straight line at constant speed . the fact that there was a vertical force on the space probe does not affect the horizontal velocity of the space probe , it only changes the vertical velocity . a constant vertical and horizontal velocity yields a diagonal straight line through space .
|
the box of burritos would either continue moving with a constant velocity—if it started with a velocity before the forces were applied—or stay at rest—if it was already at rest before the forces were applied . what does mass mean ? the property of a body to remain at rest or to remain in motion with constant velocity is called inertia .
|
what does the word inertia mean , as in where does it originate from ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
could it be determined by the shape of the throat on if people would be able to have language , or speech ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers .
|
is there any mark or hypothesis on when first speech developed ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate .
|
can the present-day hunter-gatherers in africa and other parts of the world be called homo sapiens , but not homo sapiens sapiens ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate .
|
what is the difference between homo sapiens and homo sapiens sapiens ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag .
|
when was the ice man found ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers .
|
so , if da vinci was alive say 25,000 years ago , and did n't die for a very long time ... and he still had all his intelligence of course , how far would we be technology wise now ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era .
|
is the last statue even real ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures .
|
are we to assume that there was enough biological evolution in this time to allow more fine motor functions , or is it simply the development of culture ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources .
|
does this mean that if a lower-paleolithic man was handed a tool from the neolithic age he would be able to replicate it ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources .
|
in paragraph 1 under `` technological innovation '' , it is stated that the progression of tools has been divided into the eras of lower paleolithic , upper paleolithic , mesolithic , and neolithic , but what exact innovations prompted these divisions ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ?
|
what evidence do we have that paleolithic people had developed a capacity for language ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate .
|
`` examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech '' what does indentation here means ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech .
|
how are we able to translate things from extinct language ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility .
|
are some of the words similar to modern day languages or what ?
|
overview paleolithic groups developed increasingly complex tools and objects made of stone and natural fibers . language , art , scientific inquiry , and spiritual life were some of the most important innovations of the paleolithic era . technological innovation stone tools are perhaps the first cultural artifacts which historians can use to reconstruct the worlds of paleolithic peoples . in fact , stone tools were so important in the paleolithic age that the names of paleolithic periods are based on the progression of tools : lower paleolithic , upper paleolithic , mesolithic ( middle stone age ) , and neolithic ( new stone age ) . $ ^1 $ stone tools also give us insight into the development of culture . anthropologists think paleolithic people likely hunted , foraged , and employed a communal system for dividing labor and resources . anthropologists have inferred this by drawing analogies to modern hunter-gatherer groups and by interpreting cave art which depicts group hunting . by approximately 40,000 years ago , narrow stone blades and tools made of bone , ivory , and antler appeared , along with simple wood instruments . closer to 20,000 years ago , the first known needles were produced . eventually , between 17,000 and 8,000 years ago , humans produced more complicated instruments like barbed harpoons and spear-throwers . it is likely that many tools made out of materials besides stone were prevalent but simply did not survive to the present day for scientists to observe . one exception is the neolithic “ ice man ” , found by two hikers in the ötztal alps , who was preserved in ice for 5,000 years ! he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures . without the aid of language , these things would likely have been impossible . examinations of the craniums of archaic homo sapiens suggest large brains with indentations that imply the development of brain areas associated with speech . exactly how humans developed a capacity for language is a matter of considerable debate . however , the historical record shows that language allowed for increasingly complex social structures , with an enhanced capacity for deliberation , morality , spirituality , and meaning-making . artwork such as cave painting and portable art demonstrates creativity and group structures as well . they show an interest in sharing knowledge , expressing feelings , and transmitting cultural information to later generations . though artwork from over 35,000 years ago is rare , there is ample evidence of cave paintings and statuettes from later periods . in addition to cave art , portable figurines dated to paleolithic times have been found . many of these include finely carved facial features , while others accentuate sexual organs and buttocks , such as the 25,000 year old figurine found at dolni vestonice in the modern-day czech republic . such an object shows a desire to create beautiful figurines , but some also suggest that objects like this are tied to an interest in human fertility . what do you think ? what evidence do we have that paleolithic people had developed a capacity for language ? could paleolithic people have survived in the ways that they did without language ? what do you think was the purpose of paleolithic art such as cave paintings and figurines ?
|
he was found with a robust set of stone and natural-fiber tools , including a six-foot longbow , deerskin case , fourteen arrows , a stick with an antler tip for sharpening flint blades , a small flint dagger in a woven sheath , a copper axe , and a medicine bag . language , culture and art language was perhaps the most important innovation of the paleolithic era . scientists can infer the early use of language from the fact that humans traversed large swaths of land , established settlements , created tools , traded , and instituted social hierarchies and cultures .
|
were we forced to stop speaking the language ?
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.