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electromagnetic waves vary in their wavelengths and frequencies. | (A) true (B) false | A | Although all electromagnetic waves travel at the same speed, they may differ in their wavelength and frequency. |
radio waves have the highest frequencies of all electromagnetic waves. | (A) true (B) false | B | As you can see in the Figure 1.1, gamma rays have the shortest wavelengths and highest frequencies of all electromagnetic waves. Their wavelengths are shorter than the diameter of atomic nuclei, and their frequencies are greater than 1019 hertz (Hz). Thats 10 quadrillion waves per second! Because of their high frequenc... |
radio waves have the least energy of all electromagnetic waves. | (A) true (B) false | A | Radio waves are the broad range of electromagnetic waves with the longest wavelengths and lowest frequencies. In Figure 21.7, you can see that the wavelength of radio waves may be longer than a soccer field. With their low frequencies, radio waves have the least energy of electromagnetic waves, but they still are extre... |
radio waves vary in frequency from | (A) 105 to 1012 Hz (B) 1050 to 10 (C) 120 Hz (D) c 10 (E) 500 to 101 (F) 200 Hz (G) d none of the above | A | Radio waves are the broad range of electromagnetic waves with the longest wavelengths and lowest frequencies. In Figure 21.7, you can see that the wavelength of radio waves may be longer than a soccer field. With their low frequencies, radio waves have the least energy of electromagnetic waves, but they still are extre... |
am radio waves | (A) have longer wavelengths than FM radio waves (B) are encoded with signals by changing their amplitude (C) reflect off the ionosphere (D) all of the above | D | Radio waves are the broad range of electromagnetic waves with the longest wavelengths and lowest frequencies. In Figure 21.7, you can see that the wavelength of radio waves may be longer than a soccer field. With their low frequencies, radio waves have the least energy of electromagnetic waves, but they still are extre... |
in tv broadcasts | (A) radio waves carry both sound and picture signals (B) sounds are encoded withy amplitude modulation (C) pictures are encoded with frequency modulation (D) all of the above | A | Television broadcasts also use radio waves (see Figure 1.2). For TV broadcasts, sounds are encoded with frequency modulation, and pictures are encoded with amplitude modulation. The encoded waves are broadcast from a TV tower. When the waves are received by television sets, they are decoded and changed back to sounds a... |
radioactive decay is a chemical reaction. | (A) true (B) false | B | Radioactive decay is the process in which the nuclei of radioactive atoms emit charged particles and energy, which are called by the general term radiation. Radioactive atoms have unstable nuclei, and when the nuclei emit radiation, they become more stable. Radioactive decay is a nuclearrather than chemicalreaction bec... |
radioactive decay may change one element into another. | (A) true (B) false | A | Radioactive decay is the breakdown of unstable elements into stable elements. To understand this process, recall that the atoms of all elements contain the particles protons, neutrons, and electrons. |
energy is emitted by a nucleus when it undergoes | (A) alpha decay (B) beta decay (C) gamma decay (D) any of the above | D | Nuclear energy is produced by splitting the nucleus of an atom. This releases a huge amount of energy. |
the type of radioactive decay that occurs when a nucleus emits an electron is | (A) alpha decay (B) beta decay (C) gamma decay (D) none of the above | B | There are several types of radioactive decay, including alpha, beta, and gamma decay. In all three types, nuclei emit radiation, but the nature of the radiation differs. The Table 1.1 shows the radiation emitted in each type of decay. Type Alpha decay Beta decay Gamma decay Radiation Emitted alpha particle (2 protons a... |
the type of radioactive decay that occurs when a nucleus emits two protons and two neutrons is | (A) alpha decay (B) beta decay (C) gamma decay (D) none of the above | A | There are several types of radioactive decay, including alpha, beta, and gamma decay. In all three types, nuclei emit radiation, but the nature of the radiation differs. The Table 1.1 shows the radiation emitted in each type of decay. Type Alpha decay Beta decay Gamma decay Radiation Emitted alpha particle (2 protons a... |
certain chemical processes can change one element into another. | (A) true (B) false | B | A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. A chemical change is also called a chemical reaction. Many complex chemical changes occur to produce the explosions of fireworks. An example of a simpler chemical change is the burning of methane. M... |
atoms of each element have a unique number of | (A) protons (B) neutrons (C) isotopes (D) two of the above | A | All atoms of the same element have the same number of protons, but some may have different numbers of neutrons. For example, all carbon atoms have six protons, and most have six neutrons as well. But some carbon atoms have seven or eight neutrons instead of the usual six. Atoms of the same element that differ in their ... |
all nuclei emit radiation. | (A) true (B) false | B | Radioactivity is the ability of an atom to emit, or give off, charged particles and energy from its nucleus. The charged particles and energy are called by the general term radiation. Only unstable nuclei emit radiation. They are unstable because they have too much energy, too many protons, or an unstable ratio of prot... |
nuclei may be unstable if they have | (A) too much energy (B) too many protons (C) an unstable ratio of protons to neutrons (D) any of the above | D | All the atoms of a given element have the same number of protons in their nucleus, but they may have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes. Many elements have one or more isotopes that are radioactive. These isotopes are called radioisotopes. The... |
all elements with more than 75 protons are unstable. | (A) true (B) false | B | In elements with more than 83 protons, all of the isotopes are radioactive. In the Figure 1.1, these are the elements with a yellow background. The force of repulsion among all those protons makes the nuclei unstable. Elements with more than 92 protons have such unstable nuclei that they dont even exist in nature. They... |
which of the following elements are radioactive? | (A) uranium (B) radium (C) polonium (D) all of the above | D | Radioactive decay is the breakdown of unstable elements into stable elements. To understand this process, recall that the atoms of all elements contain the particles protons, neutrons, and electrons. |
only radioactive elements have isotopes that are radioactive. | (A) true (B) false | B | In elements with more than 83 protons, all of the isotopes are radioactive. In the Figure 1.1, these are the elements with a yellow background. The force of repulsion among all those protons makes the nuclei unstable. Elements with more than 92 protons have such unstable nuclei that they dont even exist in nature. They... |
radioactive isotopes are unstable because they have too many electrons. | (A) true (B) false | B | Atoms need a certain ratio of neutrons to protons to have a stable nucleus. Having too many or too few neutrons relative to protons results in an unstable, or radioactive, nucleus that will sooner or later break down to a more stable form. This process is called radioactive decay. Many isotopes have radioactive nuclei,... |
the nucleus that is most likely to be unstable is the nucleus that has | (A) 2 protons and 2 neutrons (B) 4 protons and 4 neutrons (C) 6 protons and 8 neutrons (D) 60 protons and 90 neutrons | C | In elements with more than 83 protons, all of the isotopes are radioactive. In the Figure 1.1, these are the elements with a yellow background. The force of repulsion among all those protons makes the nuclei unstable. Elements with more than 92 protons have such unstable nuclei that they dont even exist in nature. They... |
the radioisotope of carbon is called | (A) carbon-6 (B) carbon-8 (C) carbon-13 (D) carbon-14 | D | For most other elements, isotopes are named for their mass number. For example, carbon atoms with the usual 6 neutrons have a mass number of 12 (6 protons + 6 neutrons = 12), so they are called carbon-12. Carbon atoms with 7 neutrons have an atomic mass of 13 (6 protons + 7 neutrons = 13). These atoms are the isotope c... |
chemical changes occur because of chemical reactions. | (A) true (B) false | A | A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. A chemical change is also called a chemical reaction. Many complex chemical changes occur to produce the explosions of fireworks. An example of a simpler chemical change is the burning of methane. M... |
an example of a chemical change is a candle burning. | (A) true (B) false | A | A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. A chemical change is also called a chemical reaction. Many complex chemical changes occur to produce the explosions of fireworks. An example of a simpler chemical change is the burning of methane. M... |
any substance that starts a chemical reaction is called a | (A) reactor (B) regent (C) reactant (D) none of the above | C | A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be elements or compounds. A chemical reaction can be represented by thi... |
any substance that results from a chemical reaction is called a | (A) producer (B) product (C) productor (D) none of the above | B | A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be elements or compounds. A chemical reaction can be represented by thi... |
products of a combustion reaction include | (A) fuel (B) oxygen (C) water (D) two of the above | C | A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). For example, in the Figure usually referred to as fuel. The products of a complete combustion reaction include carbon dioxide (CO2 ) and water vapor (H2 O). The reaction typically gives off heat and light as well. The general equation for a... |
all changes in matter are the result of chemical reactions. | (A) true (B) false | B | Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. How can you tell whether a change in matter involves a chemical reaction? Often... |
signs that a chemical reaction has occurred include a change in | (A) temperature (B) color (C) state (D) two of the above | D | A change in color is just one of several potential signs that a chemical reaction has occurred. Other potential signs include: Change in temperature-Heat is released or absorbed during the reaction. Production of a gas-Gas bubbles are released during the reaction. Production of a solid-A solid settles out of a liquid s... |
which of the following is a sign of a chemical reaction? | (A) A liquid changes to a solid (B) A liquid changes to a gas (C) A solid changes to a gas (D) A gas is released from a liquid | D | A change in color is just one of several potential signs that a chemical reaction has occurred. Other potential signs include: Change in temperature-Heat is released or absorbed during the reaction. Production of a gas-Gas bubbles are released during the reaction. Production of a solid-A solid settles out of a liquid s... |
the solid lumps in cottage cheese are an example of a precipitate. | (A) true (B) false | A | When water evaporates, it leaves behind a solid precipitate of minerals, as shown in Figure 1.2. When the water in glass A evaporates, the dissolved mineral particles are left behind. Water can only hold a certain amount of dissolved minerals and salts. When the amount is too great to stay dissolved in the water, the p... |
the release of gas bubbles is a sign of a chemical reaction. | (A) true (B) false | A | Look carefully at the Figures 1.1, 1.2, and 1.3. All of the photos demonstrate chemical reactions. For each photo, identify a sign that one or more chemical reactions have taken place. A burning campfire can warm you up on a cold day. Dissolving an antacid tablet in water produces a fizzy drink. Adding acid to milk pro... |
which of the following does not involve chemical reactions? | (A) Leaves change color in the fall (B) A pond freezes over in the winter (C) A fire burns a pile of fallen leaves (D) Fallen leaves decay in a compost pile | B | Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. How can you tell whether a change in matter involves a chemical reaction? Often... |
less reactive elements replace more reactive elements in compounds. | (A) true (B) false | B | A replacement reaction occurs when elements switch places in compounds. This type of reaction involves ions (electrically charged versions of atoms) and ionic compounds. These are compounds in which positive ions of a metal and negative ions of a nonmetal are held together by ionic bonds. Generally, a more reactive ele... |
replacement reactions always involve ionic compounds. | (A) true (B) false | A | Replacement reactions involve ions. They occur when ions switch places in compounds. There are two types of replacement reactions: single and double. Both types are described below. |
a single replacement reaction always involves two reactant compounds. | (A) true (B) false | B | Replacement reactions involve ions. They occur when ions switch places in compounds. There are two types of replacement reactions: single and double. Both types are described below. |
which of the following is a single replacement reaction? | (A) FeS + 2HCl → H2S + FeCl2 (B) Fe + CuSO4 → FeSO4 + Cu (C) AgNO3 + NaCl ---> AgCl + NaNO3 (D) none of the above | B | A single replacement reaction occurs when one ion takes the place of another in a single compound. This type of reaction has the general equation: A + BC ! B + AC Do you see how A has replaced B in the compound? The compound BC has become the compound AC. An example of a single replacement reaction occurs when potassiu... |
the general equation for a double replacement reaction is | (A) AB + CD → BC + DA (B) AB + C + D → AD + CB (C) AB + C → AC + B (D) none of the above | D | A double replacement reaction occurs when two compounds exchange ions. This produces two new compounds. A double replacement reaction can be represented by the general equation: AB +CD ! AD +CB Do you see how B and D have changed places? Both reactant compounds have changed. An example of a double replacement reaction ... |
a compound in a replacement reaction always consists of | (A) a positive ion and a negative ion (B) a metal ion and a nonmetal ion (C) two negative metal ions (D) two of the above | D | A replacement reaction occurs when elements switch places in compounds. This type of reaction involves ions (electrically charged versions of atoms) and ionic compounds. These are compounds in which positive ions of a metal and negative ions of a nonmetal are held together by ionic bonds. Generally, a more reactive ele... |
in rutherfords experiments, most of the alpha particles | (A) were deflected by the gold foil (B) passed straight through the gold foil (C) bounced straight back from the gold foil (D) none of the above | B | In 1899, Rutherford discovered that some elements give off positively charged particles. He named them alpha particles (a). In 1911, he used alpha particles to study atoms. He aimed a beam of alpha particles at a very thin sheet of gold foil. Outside the foil, he placed a screen of material that glowed when alpha parti... |
from his results, rutherford concluded that the positive charge of an atom is | (A) less than the negative charge of the atom (B) spread evenly throughout the atom (C) concentrated in a tiny area at the center of the atom (D) two of the above | C | Based on his results, Rutherford concluded that all the positive charge of an atom is concentrated in a small central area. He called this area the nucleus. Rutherford later discovered that the nucleus contains positively charged particles. He named the positive particles protons. Rutherford also predicted the existenc... |
based on his research, rutherford thought that most of an atom consists of empty space. | (A) true (B) false | A | Rutherford made the same inferences. He concluded that all of the positive charge and virtually all of the mass of an atom are concentrated in one tiny area and the rest of the atom is mostly empty space. Rutherford called the area of concentrated positive charge the nucleus. He predictedand soon discoveredthat the nuc... |
rutherford predicted the existence of neutrons but failed to find them. | (A) true (B) false | A | Based on his results, Rutherford concluded that all the positive charge of an atom is concentrated in a small central area. He called this area the nucleus. Rutherford later discovered that the nucleus contains positively charged particles. He named the positive particles protons. Rutherford also predicted the existenc... |
the melting points of saturated hydrocarbons are determined mainly by their number of | (A) double bonds (B) hydrogen atoms (C) carbon atoms (D) none of the above | C | Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogen. You can see an examp... |
which saturated hydrocarbon has the chemical formula c2h6? | (A) methane (B) ethane (C) propane (D) butane | B | Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogen. You can see an examp... |
which saturated hydrocarbon has eight carbon atoms? | (A) pentane (B) hexane (C) heptane (D) octane | D | Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogen. You can see an examp... |
methane has a higher boiling point than ethane. | (A) true (B) false | B | Natural gas is mostly methane. |
some alkanes are solids are room temperature. | (A) true (B) false | A | Saturated hydrocarbons are given the general name of alkanes. The name of specific alkanes always ends in -ane. The first part of the name indicates how many carbon atoms each molecule of the alkane has. The smallest alkane is methane. It has just one carbon atom. The next largest is ethane with two carbon atoms. The c... |
types of graphs include | (A) bar graphs (B) line graphs (C) circle graphs (D) all of the above | D | Graphs are very useful tools in science. They can help you visualize a set of data. With a graph, you can actually see what all the numbers in a data table mean. Three commonly used types of graphs are bar graphs, circle graphs, and line graphs. Each type of graph is suitable for showing a different type of data. |
different types of graph are best suited for representing different types of data. | (A) true (B) false | A | Graphs are very useful tools in science. They can help you visualize a set of data. With a graph, you can actually see what all the numbers in a data table mean. Three commonly used types of graphs are bar graphs, circle graphs, and line graphs. Each type of graph is suitable for showing a different type of data. |
to be useful, a scientific model must | (A) closely represent the real thing in important ways (B) be simpler than the real thing (C) be easier to understand than the real thing (D) all of the above | D | Scientific models are useful tools in science. Earths climate is extremely complex, with many factors that are dependent on one another. Such a system is impossible for scientists to work with as a whole. To deal with such complexity, scientists may create models to represent the system that they are interested in stud... |
a chemical equation is an example of a model. | (A) true (B) false | A | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
a road map is a three-dimensional model. | (A) true (B) false | B | Imagine you are going on a road trip. Perhaps you are going on vacation. How do you know where to go? Most likely, you will use a map. A map is a picture of specific parts of Earths surface. There are many types of maps. Each map gives us different information. Lets look at a road map, which is the probably the most co... |
basic concepts in chemistry include | (A) atoms and molecules (B) chemical reactions (C) energy (D) all of the above | D | Chemistry is the study of the structure, properties, and interactions of matter. Important concepts in chemistry include physical changes, such as water freezing, and chemical reactions, such as fireworks exploding. Chemistry concepts can answer all the questions on the left page of the notebook in Figure 1.5. Do you k... |
which of the following changes involve(s) chemical reactions? | (A) candle burning (B) fruit spoiling (C) meat cooking (D) all of the above | D | Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. How can you tell whether a change in matter involves a chemical reaction? Often... |
important physics concepts include | (A) motion (B) forces (C) energy (D) all of the above | D | Physics is the study of energy and how it interacts with matter. Important concepts in physics include motion, forces such as magnetism and gravity, and different forms of energy. Physics concepts can answer all the questions on the right page of the notebook in Figure 1.5. |
which of the following is an example of a force? | (A) magnetism (B) motion (C) light (D) none of the above | A | Force is defined as a push or a pull acting on an object. Examples of forces include friction and gravity. Both are covered in detail later in this chapter. Another example of force is applied force. It occurs when a person or thing applies force to an object, like the girl pushing the swing in Figure 13.1. The force o... |
which of the following is a form of energy? | (A) gravity (B) sound (C) matter (D) two of the above | B | The different forms of energy are defined and illustrated below. 1. Mechanical energy is the energy of movement. It is found in objects that are moving or have the potential to move. 2. Chemical energy is energy that is stored in the bonds between the atoms of compounds. If the bonds are broken, the energy is released ... |
examples of screws include | (A) wood screws (B) spiral staircases (C) bottle caps (D) all of the above | D | A screw is a simple machine that consists of an inclined plane wrapped around a central cylinder. No doubt you are familiar with screws like the wood screw in the left-hand side of the Figure 1.1. The cap of the bottle pictured on the right is another example of a screw. Screws move objects to a greater depth (or highe... |
uses of screws include | (A) raising objects (B) lowering objects (C) holding objects together (D) all of the above | D | A screw is a simple machine that consists of an inclined plane wrapped around a central cylinder. No doubt you are familiar with screws like the wood screw in the left-hand side of the Figure 1.1. The cap of the bottle pictured on the right is another example of a screw. Screws move objects to a greater depth (or highe... |
screws help us do work by increasing the | (A) amount of force that is applied (B) distance over which force is applied (C) speed with which force is applied (D) two of the above | A | The mechanical advantage of a simple machine is the factor by which it multiplies the force applied to the machine. It is the ratio of the output force to the input force. The force applied by the screw (output force) is always greater than the force applied to the screw (input force). Therefore, the mechanical advanta... |
the input force is applied to the inclined plane of a screw. | (A) true (B) false | A | Two simple machines that are based on the inclined plane are the wedge and the screw. Both increase the force used to move an object because the input force is applied over a greater distance than the output force. |
the mechanical advantage of a screw is always less than 1. | (A) true (B) false | B | The mechanical advantage of a simple machine is the factor by which it multiplies the force applied to the machine. It is the ratio of the output force to the input force. The force applied by the screw (output force) is always greater than the force applied to the screw (input force). Therefore, the mechanical advanta... |
in the picture above, it takes it takes more turns of the screw on the right to go the same distance into the wood as the screw on the left. | (A) true (B) false | A | The mechanical advantage of a simple machine is the factor by which it multiplies the force applied to the machine. It is the ratio of the output force to the input force. The force applied by the screw (output force) is always greater than the force applied to the screw (input force). Therefore, the mechanical advanta... |
significant figures for a measurement always include | (A) all the digits that can be read directly from the measuring device (B) one digit estimated by the person taking the measurement (C) at least two digits to the right of the decimal point (D) two of the above | D | The examples above show that its easy to count the number of significant figures when you are making a measure- ment. But what if someone else has made the measurement? How do you know which digits are known for certain and which are estimated? How can you tell how many significant figures there are in the measurement?... |
assume that you take a measurement with a metric ruler that is divided into individual millimeters. which measurement has the correct number of significant figures? | (A) 21 mm (B) 210 mm (C) 2100 mm (D) none of the above | B | Youve probably been using a ruler to measure length since you were in elementary school. But you may have made most of the measurements in English units of length, such as inches and feet. In science, length is most often measured in SI units, such as millimeters and centimeters. Many rulers have both types of units, o... |
which of the following is a correct rule for counting significant figures? | (A) Leading zeroes are always significant (B) Zeroes between nonzero digits are not significant (C) Zeroes that show only where the decimal point falls are not significant (D) Trailing zeroes are never significant | C | The examples above show that its easy to count the number of significant figures when you are making a measure- ment. But what if someone else has made the measurement? How do you know which digits are known for certain and which are estimated? How can you tell how many significant figures there are in the measurement?... |
when measurements are used in a calculation, the answer has the same number of significant figures as the measurement with the most signficant figures. | (A) true (B) false | B | When measurements are used in a calculation, the answer cannot have more significant figures than the measurement with the fewest significant figures. This explains why the homework answer above is wrong. It has more significant figures than the measurement with the fewest significant figures. As another example, assum... |
work is calculated with the equation work = force/distance. | (A) true (B) false | B | Work is the use of force to move an object. It is directly related to both the force applied to the object and the distance the object moves. Work can be calculated with this equation: Work = Force x Distance. |
the output distance of a machine is always | (A) less than the input distance (B) greater than the input distance (C) equal to the input distance (D) none of the above | D | A machine is any device that makes work easier by changing a force. Work is done whenever a force moves an object over a distance. The amount of work done is represented by the equation: Work = Force x Distance When you use a machine, you apply force to the machine. This force is called the input force. The machine, in... |
a machine increases the amount of work that is done. | (A) true (B) false | B | Contrary to popular belief, machines do not increase the amount of work that is done. They just change how the work is done. Machines make work easier by increasing the amount of force that is applied, increasing the distance over which the force is applied, or changing the direction in which the force is applied. Q: I... |
if a machine increases force, it must apply the force over a longer distance. | (A) true (B) false | B | Contrary to popular belief, machines do not increase the amount of work that is done. They just change how the work is done. Machines make work easier by increasing the amount of force that is applied, increasing the distance over which the force is applied, or changing the direction in which the force is applied. Q: I... |
machines that increase the distance over which force is applied include | (A) steering wheels (B) pliers (C) rakes (D) two of the above | C | Examples of machines that increase the distance over which force is applied are leaf rakes and hammers (see Figure which the force is applied, but it reduces the strength of the force. |
all sound waves begin with vibrating matter. | (A) true (B) false | A | All sounds begin with vibrating matter. It could be the ground vibrating when a tree comes crashing down. Or it could be guitar strings vibrating when they are plucked. You can see a guitar string vibrating in Figure 20.2. The vibrating string repeatedly pushes against the air particles next to it. The pressure of the ... |
vibrations spread through the air in all directions from a vibrating object. | (A) true (B) false | A | All sounds begin with vibrating matter. It could be the ground vibrating when a tree comes crashing down. Or it could be guitar strings vibrating when they are plucked. You can see a guitar string vibrating in Figure 20.2. The vibrating string repeatedly pushes against the air particles next to it. The pressure of the ... |
sound waves are | (A) surface waves (B) transverse waves (C) longitudinal waves (D) none of the above | C | Sound is a form of energy that travels in waves. Sound waves cant travel through empty space, but they can travel through gases. Gases in the air allow us to hear most of the sounds in our world. Because of air, you can hear birds singing, horns tooting, and friends laughing. Without the atmosphere, the world would be ... |
sound waves can travel only through gases. | (A) true (B) false | B | Sound waves are mechanical waves, so they can travel only though matter and not through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air ... |
materials that tend to absorb rather than transmit sound waves include | (A) foam rubber (B) glass (C) metal (D) all of the above | A | Most of the sounds we hear reach our ears through the air, but sounds can also travel through liquids and solids. If you swim underwateror even submerge your ears in bathwaterany sounds you hear have traveled to your ears through the water. Some solids, including glass and metals, are very good at transmitting sounds. ... |
sound waves are mechanical waves. | (A) true (B) false | A | Sound waves are mechanical waves, so they can travel only though matter and not through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air ... |
visible light includes all the wavelengths of light that the human eye can detect. | (A) true (B) false | A | Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength appears violet. In between are all the o... |
some animals can see infrared or ultraviolet light. | (A) true (B) false | A | Visible light includes all the wavelengths of light that the human eye can detect. It allows us to see objects in the world around us. Without visible light, we would only be able to sense most objects by sound, touch, or smell. Like humans, most other organisms also depend on visible light, either directly or indirect... |
objects that produce light by incandescence include | (A) candles (B) bonfires (C) oil lamps (D) all of the above | D | An incandescent light bulb like the one pictured in the Figure 1.1 produces visible light by incandescence. Incan- descence occurs when something gets so hot that it glows. An incandescent light bulb contains a thin wire filament made of tungsten. When electric current passes through the filament, it gets extremely hot... |
substances that produce light by electroluminescence include | (A) diamond (B) emerald (C) neon (D) all of the above | C | Some objects produce light without becoming very hot. They generate light through chemical reactions or other processes. Producing light without heat is called luminescence. Luminescence, in turn, can occur in several different ways: One type of luminescence is called fluorescence. In this process, a substance absorbs ... |
speed determines how far something moves in a given amount of time. | (A) true (B) false | A | How fast or slow something moves is its speed. Speed determines how far something travels in a given amount of time. The SI unit for speed is meters per second (m/s). Speed may be constant, but often it varies from moment to moment. |
the si unit for speed is | (A) cm/s (B) m/s (C) m/h (D) km/h | B | How fast or slow something moves is its speed. Speed determines how far something travels in a given amount of time. The SI unit for speed is meters per second (m/s). Speed may be constant, but often it varies from moment to moment. |
if you ride your bike 20 miles and it takes you 120 minutes, what is your average speed? | (A) 6 m/h (B) 10 m/h (C) 20 m/h (D) 60 m/h | B | Even if speed varies during the course of a trip, its easy to calculate the average speed by using this formula: speed = distance time For example, assume you go on a car trip with your family. The total distance you travel is 120 miles, and it takes 3 hours to travel that far. The average speed for the trip is: 120 mi... |
if you know your average speed and how long you have been traveling, then you can calculate your distance with the formula | (A) distance = speed/time (B) distance = speed x time (C) distance = time/speed (D) none of the above | B | If you know the average speed of a moving object, you can calculate the distance it will travel in a given period of time or the time it will take to travel a given distance. To calculate distance from speed and time, use this version of the average speed formula given above: distance = speed time For example, if a ca... |
to calculate the amount of time it takes to travel a given distance at a certain speed, you would use the formula | (A) time = distance/speed (B) time = distance x speed (C) time = speed/distance (D) none of the above | A | If you know the average speed of a moving object, you can calculate the distance it will travel in a given period of time or the time it will take to travel a given distance. To calculate distance from speed and time, use this version of the average speed formula given above: distance = speed time For example, if a ca... |
the speed of sound is faster than the speed of light. | (A) true (B) false | B | The speed of sound is the distance that sound waves travel in a given amount of time. You probably already know that sound travels more slowly than light. Thats why you usually see the flash of lightning before you hear the boom of thunder. However, the speed of sound isnt constant. It varies depending on the medium of... |
sound waves can travel only through matter. | (A) true (B) false | A | Sound waves are mechanical waves, so they can travel only though matter and not through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air ... |
sound waves generally travel most quickly through | (A) gases (B) liquids (C) solids (D) plasma | C | Sound waves are mechanical waves, and mechanical waves can only travel through matter. The matter through which the waves travel is called the medium (plural, media). The Table 1.1 gives the speed of sound in several different media. Generally, sound waves travel most quickly through solids, followed by liquids, and th... |
sound waves travel more quickly through dry air than moist air. | (A) true (B) false | B | Sound waves are mechanical waves, and mechanical waves can only travel through matter. The matter through which the waves travel is called the medium (plural, media). The Table 1.1 gives the speed of sound in several different media. Generally, sound waves travel most quickly through solids, followed by liquids, and th... |
the speed of sound through air is fastest when the air temperature is | (A) 0 °C (B) 20 °C (C) 40 °C (D) 60 °C | D | The speed of sound also depends on the temperature of the medium. For a given medium, sound has a slower speed at lower temperatures. You can compare the speed of sound in dry air at different temperatures in the following Table 1.2. At a lower temperature, particles of the medium are moving more slowly, so it takes th... |
electric charges can travel easily through dry air. | (A) true (B) false | B | Static electricity is a buildup of electric charges on objects. Charges build up when negative electrons are transferred from one object to another. The object that gives up electrons becomes positively charged, and the object that accepts the electrons becomes negatively charged. This can happen in several ways. One w... |
lighting can occur between a cloud and | (A) another part of the same cloud (B) a different cloud (C) the ground (D) any of the above | D | So much energy collects in cumulonimbus clouds that a huge release of electricity, called lightning, may result (Figure 1.4). The electrical discharge may be between one part of the cloud and another, two clouds, or a cloud and the ground. Lightning heats the air so that it expands explosively. The loud clap is thunder... |
lightning is an example of static discharge. | (A) true (B) false | A | Another example of static discharge, but on a much larger scale, is lightning. You can see how it occurs in the following diagram (Figure 1.1). During a rainstorm, clouds develop regions of positive and negative charge due to the movement of air molecules, water drops, and ice particles. The negative charges are concen... |
during a rainstorm, negative charges become concentrated at the | (A) surface of the ground (B) top of the clouds (C) base of the clouds (D) two of the above | C | Another example of static discharge, but on a much larger scale, is lightning. You can see how it occurs in the following diagram (Figure 1.1). During a rainstorm, clouds develop regions of positive and negative charge due to the movement of air molecules, water drops, and ice particles. The negative charges are concen... |
a surface wave is one type of mechanical wave. | (A) true (B) false | A | There are three types of mechanical waves. They differ in how they travel through a medium. The three types are transverse, longitudinal, and surface waves. All three types are described in detail below. |
an ocean wave is an example of a surface wave. | (A) true (B) false | A | A surface wave is a wave that travels along the surface of a medium. The medium is the matter through which the wave travels. Ocean waves are the best-known examples of surface waves. They travel on the surface of the water between the ocean and the air. Q: What do you think causes ocean waves? A: Most ocean waves are ... |
in deep water, how do particles of water move when a surface wave passes through them? | (A) up and down (B) back and forth (C) in an overall circular motion (D) all of the above | D | In deep water, particles of water just move in circles. They dont actually move closer to shore with the energy of the waves. However, near the shore where the water is shallow, the waves behave differently. Look at the Figure 1.2. You can see how the waves start to drag on the bottom in shallow water. This creates fri... |
why do surface waves break along the shore? | (A) The waves start to drag on the bottom (B) The tops of the waves speed up (C) The waves become less steep (D) all of the above | A | In deep water, particles of water just move in circles. They dont actually move closer to shore with the energy of the waves. However, near the shore where the water is shallow, the waves behave differently. Look at the Figure 1.2. You can see how the waves start to drag on the bottom in shallow water. This creates fri... |
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