source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-1501 | paleontology, fossils, desert
Title: Why are many fossils found in deserts? Why are deserts famous for fossils? Is it a coincidence? Some examples:
Giant Catfish Fossil Found in Egyptian Desert
Chile's stunning fossil whale graveyard explained
Giant Dinosaur Fossil Found in Sahara Desert I would contend that the fact that the location is a desert has little to nothing to do in most cases to the existence of fossils at the location. Most of the fossils in the location, at least the ones that make most headlines like major dinosaur deposits, were left there millions of years ago. The fact that a location today is a desert has no indication of what the climate, or even where on the globe that location was 50 or 100 million years ago.
Do not forget about plate tectonics and climate change. One can go to places like the Judith Basin in Montana, a relatively harsh area of North American Bad Lands, desert or near desert like conditions with cold winters and find fields of fossils from animals that are believed to have lived in tropic marshes of in oceans, because at the time those animals lived, what is now Montana was not inland, and was not at a Northern location. Millions of years ago it was an undersea plate, thus it has layers of limestone made from ancient single cell sea creatures and sometimes larger objects that were entrapped and preserved as larger fossils. At other times, those plates rose from the sea floor and homed some of the large creatures, like T-Rex that lived, thrived and sometimes survive as fossils.
Later, that plate move and ended up inland, in what is not North America. Glaciers, wind, and water may have stripped off many layers of deposits and left exposed or close to exposed the layers of interest to fossil hunters. Desert regions tend to be subjected to this type of erosion and exposure making such finds easier. If those same fossils were in and area such as a rich planes area with plentiful plant growth and never subjected to glacial scouring, they could be, and may very well be, right below your feet but under many layers of soil and decaying vegetation, river sediment and other deposits rendering them out of sight and out of reach.
The following is multiple choice question (with options) to answer.
Desert lizards may sometimes appear as | [
"buildings",
"rock particles",
"trees",
"cement"
] | B | some lizards live in desert habitats |
OpenBookQA | OpenBookQA-1502 | Since we have $21$ terms taking $20$ possible values, there are some $0 \le i < j \le 20$ such that $S_i = S_j$. It follows that the total number of hours of study between days $i+1$ and $j$ (inclusive) is a multiple of $20$.
If it is not exactly equal to $20$ hours, then it must be at least $40$ hours. However, this is over a span of at most $20$ days. Dividing this into three periods of at most $7$ days (say the first week, second week, and third week), by averaging we find that she must have worked at least $14$ hours during one of the weeks, which is not allowed.
Thus she must actually have studied exactly $20$ hours between days $i+1$ and $j$.
• Yes, that's a little cleaner as route to Wiley's lemma.Thanks. – Joffan Jul 17 '16 at 23:05
• @Joffan, agreed. It's indeed cleaner to use 20 "holes" with 21 "pigeons" rather than separating $S_l=S_i+20$ as an individual case in my proof. Thank you, Shagnik. – Wiley Jul 18 '16 at 3:59
The proof consists of two parts.
• Part I: Prove that a period of $20$ days is enough such that there must exist some period of consecutive days during which totally $20$ hours are spent on studying.
• Part II: A counterexample which shows that $19$ days are not enough is presented.
Proof of Part I
The following is multiple choice question (with options) to answer.
Twenty four hours contains one | [
"high tide",
"4 million seconds",
"solar cycle",
"week"
] | C | one day is equal to 24 hours |
OpenBookQA | OpenBookQA-1503 | geology, geography, satellite-oddities
Title: Round structure in southern United States Assuming here might be someone who knows something about this, I wanted to ask what is behind this round structure I have spotted today on Google Earth:
There seems to be a large (~200 km), nearly perfect half-circle covering the states of Alabama, Mississippi and Tennessee. How could this regular structure possibly originate? I did some research on the web, but could not find anything. It looks a bit like an impact crater, but there is none listed in this location and especially of this large size. So how did this structure emerge? This is a sedimentary sequence representing the shoreline of a Cretaceous-Paleogene inland sea, the Western Interior Seaway. You can look at the sequence of sediments laid down in the USGS Geological Map of North America. I recommend downloading the Southern Sheet in high resolution and the Explanation Sheet to explain what's going on.
The land use pattern as seen by other people answering this question is actually putting the effect in front of the cause; due to the nature of these sediments being a positive influence on the fertility of the land, it is more likely to be used for farming.
The following is multiple choice question (with options) to answer.
One way new land can be formed is by | [
"growing it in transplanting it",
"having molten rock cool above sea level",
"creating a dam around a body of water",
"cooling burned plants with water"
] | B | new land can be formed by volcanoes erupting by lava cooling |
OpenBookQA | OpenBookQA-1504 | the-sun, light, rotation, planetary-atmosphere
Title: Why is twilight longer in summer than winter and shortest at the equinox I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with that all year.
While doing some research for this, I noticed something that surprised me. Check out this disparity between astronomical sunrise to civil sunrise for the solstices and equinox (the latter two adjusted for daylight saving time):
Date/Astronomical/Civil/Disparity
Dec 20: 0533 - 0640 (67 minutes)
Mar 20: 0526 - 0630 (64 minutes)
Jun 20: 0320 - 0451 (91 minutes)
To be honest, these sets of ranges surprise me for multiple reasons. I clearly don't know what I don't know, but here are some questions I can formulate:
Why would twilight be longer in summer than winter? Before seeing this data, I had assumed that since the sun makes a more perpendicular path through the horizon in summer that twilight would be shorter in summer than in winter. After all, in winter the sun takes a "slanted" path across the horizon. Wouldn't the summer's path be more direct and therefore quicker?
OK: seeing this empirical evidence I conclude that something is wrong with my premise that forms my first question. Summer twilight is longer in summer than winter. However, I still would have assumed that March 20 would have had a twilight length in between the two solstices. But it's not! Why does the equinox have the shortest twilight?
Appended 5/13/2014:
I didn't want to leave my original incorrect statement in here without flagging it. As Cheekhu points out below, the sun does not follow a more perpendicular path in summer than winter, as I had erroneously assumed and stated above. See his post for more details. See this diagram,
The following is multiple choice question (with options) to answer.
If it's been twelve weeks since you put on shorts, and you notice today the hours of light and dark are just about equal, how long will it be until Winter? | [
"just over a year",
"around thirteen weeks or so",
"when G.R.R. Martin says it's here",
"when the groundhog sees its shadow"
] | B | a new season occurs once per three months |
OpenBookQA | OpenBookQA-1505 | evolution, species
Title: Reasons why living fossils exist?
A living fossil is a living species (or clade) that
appears to be similar to another species otherwise known only from fossils,
typically with no close living relatives.
A living fossil is considered as a successful organism, which has made its way through many major extinction events. Also, the morphology of living fossils resemble some species of organisms which we know only through their fossil remains.
What is the reason for a particular type of species to become a living fossil; is the engineering of this particular species extraordinary, in that it can survive any selection process encountered thus far?
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Have these organisms modified themselves, so that currently their morphology seems to be similar to a fossil organism? One part of your question betrays a serious error:
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Actually the reverse is true; constancy of form can only be maintained in the presence of continuous selective pressure. It's just that this is stabilising selection that acts to maintain the existing form rather than push the organism to new morphologies. In fact, most selection acts in this manner. This shouldn't surprise you: organisms are typically well adapted to their environments so changes are more likely to reduce fitness than increase fitness.
It's also worth noting that although living fossils show little morphological change they can continue to show change at the molecular level at rates as high as, or higher than, other organisms - e.g. (May et al 2007; Cao et al 2013).
The following is multiple choice question (with options) to answer.
If an organism is a living thing, it will always | [
"cry",
"respirate",
"do magic",
"walk a rope"
] | B | all animals breathe |
OpenBookQA | OpenBookQA-1506 | species-identification, botany, ecology
Title: Algae or Lichen identification. Coastal BC, Canada I have tried all books and internet resources I know of, but I still have no idea what this might be — a lichen or something else.
At first glimpse, I thought it was something man-made and unnatural, but then I looked closer and saw how it appears to be attached and growing. It grows on exposed rocks well above the high tide. The photo is taken in late March, on northern Vancouver Island. It's loosely attached to the rock.
It was somewhat abundant around the general area (within of a few km), but I haven't seen it elsewhere - although I'm not from BC so there might be a lot of this around.
The water droplet in the lower right corner give a rough sense of scale.
Edit:
Adding another photo in which I just noticed a streak of white, which I included in original resolution. I want to propose you expand your search to a broader taxonomic scope. Specifically, I think you might be looking at a species of "red" green algae (family: Trentepohliaceae).
From Nelson et al. (2011):
All Trentepohliaceae have filamentous growth forms and often contain large amounts of carotenoid pigments (ß-carotene and hematochrome), causing the algae to appear yellow orange in color (Thompson and Wujek 1997, Lo´pez-Bautista et al. 2002).
The Trentepohliaceae contains five genera: (Trentepohlia, Printzina, Phycopeltis, Cephaleuros and Stomatochroon) and 70+ species worldwide.
For example, the following algae (picture from England) looks fairly similar to your specimen:
Trentepohlia aurea
Source: David Fenwick
If your specimen is a species in this family of algae, it is most likely in the Trentepohlia genus (or possibly Printzina genus).
Trentepohlia is a genus of filamentous chlorophyte green algae in the family Trentepohliaceae.
Typically orange or yellow in color.
Live on tree trunks and wet rocks or symbiotically in lichens.
Here's a picture of a free-living Trentepohlia species from coastal Oregon, USA:
Source: Richard C. Hoyer (2015)
The following is multiple choice question (with options) to answer.
Which place are we likely to find algae? | [
"white clouds in the sky",
"a small hidden puddle",
"an old tall building",
"a field of grass"
] | B | algae is found in bodies of water |
OpenBookQA | OpenBookQA-1507 | bacteriology
Title: How quickly is antibiotic resistance lost? I would imagine the bacterial genome is highly conserved and limited in its space, but maybe I am wrong.
If you were to take a strain of antibiotic resistant bacteria and kept them isolated, but fed well and so forth, how long would it take for them to lose their resistance? A year? A decade? 100 years? 1000 years? At some point it seems like that trait would disappear, but I have no feeling for how long. Please support your answer with a relevant citation.
EDIT:
My purpose is simple: I am thinking about a strategy for dealing with antibiotic resistance. If we were to ban them across the entire world (could be impossible) how long would we need to wait before they would be usable again. If it was a matter of years, then we could almost do a rotation of existing antibiotics (if we had enough) because I would rather not live in post-antiobitic world. Antibiotic resistances in bacteria is commonly encoded by extrachromosomal DNA, the plasmids. These are circular pieces of DNA, which are much smaller than the hosts genome and which replicate independently from it. See the image from the Wikipedia:
These plasmids can be transfered between different bacterial cells, which then also get resistant. Plasmids are divided between daughter cells, when the parent cell divides. One of the few exceptions seems to be Mycobacterium tuberculosis, which does not seem to carry plasmids but also develops resistances. It has been hypothesized that they contain extrachromosomal single-stranded DNA ("Does Mycobacterium tuberculosis have plasmids?")
Regarding your question: Plasmids which carry antibiotic resistances will only disappear, when the antibiotic is not seen for a while, since the cells, which don't carry it, have a growth advantage over cells who are still carriers (since they save the energy of forming the plasmid). However, these resistance plasmids are nothing new, evolutionary speaking. They appeared as a countermeasure against fungal toxins.
In the lab, bacterial strains loose plasmids within a few days, when not kept under selection pressure according to my experience. There are a few paper who looked into it:
The following is multiple choice question (with options) to answer.
A skin bacterium loses its habitat when | [
"you cut off your finger nails",
"you eat pepperoni pizza",
"you brush your teeth",
"you blow your nose"
] | A | if a habitat is removed then that habitat is destroyed |
OpenBookQA | OpenBookQA-1508 | power-engineering
Title: Why are hydropower plants always wheel-shaped and not flat? Question:
Why are there no flat power generators like in the picture below, that work on the surface of shallow, but steadily flowing rivers ? (As a floating micropower plant.)
The picture shows a conveyer belt with vanes/blades(?) attached to it. The water flow moves the conveyer belt. A generator could be attached to the front and back "wheel" of the belt.
Here's a video of something similar. I would just build it on a larger river.
Why would I ask this?
There are much more flat rivers than waterfall-like structures on this planet. Using them looks like a much more non-nature-inversive, cheap solution. Having a longer surface should supply better drag by flowing water. When you want to solve a problem, the best start is to look at previous attempts. To provide some perspective, I'm doing that for you now. You are not looking at a typical hydro power plant where a dam provides a high head, and the flow is ducted onto a a francis or pelton turbine. You are describing a microhydropower installation with a floating turbine.
Floating hydrpower allows capturing some power without building a dam. The turbine could be placed in or near the middle of the river, where the current is fastest. An installation with a damn will always harvest vastly more power from the same river.
Before electrical power transmission became widespread, there used to be boat mills - workshops with machinery driven by water wheels, placed on boats.
(Boat mill in Servia, 1900, Image from lowtechmagazine page on boat mills)
Improvised versions have also been used for electricity generation.
Floating hydro power is, AFAICT, an ongoing area of developement. The two most common turbine shapes appear to be a propeller hanging from buoys:
(Image source)
... Or some sort of flat paddle wheel:
Vertical axis turbines also exist.
I think Kamran explains quite well why a propeller or a paddle wheel is used, rather than a conveyor belt. I will just add this: Look at the water wheel in the direction of flow: You want to maximise area here.
The following is multiple choice question (with options) to answer.
A large turbine in a field can produce electricity to power devices when | [
"a breeze is floating",
"a child is crying",
"a dog is barking",
"clouds are very thin"
] | A | wind is used for producing electricity |
OpenBookQA | OpenBookQA-1509 | geomorphology
Title: What causes these mound-like ground formations? Whilst riding on Mam Tor in Castleton, England I came across this scene (not my photo) and I would like to know what causes the formations which I have ringed in red. They look like piles of earth have been deposited a long time ago, but clearly that can't be the case, so what causes them?
Another image of these mounds They're landslide deposits; Mam Tor gets its name, which translates as "mother hill", from the regular landslides that come off the higher slopes and form hillocks further down into the valley.
The following is multiple choice question (with options) to answer.
What causes erosion? | [
"paper",
"gales",
"wood",
"money"
] | B | wind causes erosion |
OpenBookQA | OpenBookQA-1510 | optics, atmospheric-science
Title: Why do mountains disappear into the distance? Traveling south on CA 99 we noticed that atmospheric conditions were exceptionally clear and played a little game attempting to determine how far away we could identify Shasta. As we got further and further away it got smaller, greyer, and harder to locate. I took to using these closer (green) low hills that were nearly aligned with it to locate it. As expected, the low hills went down below the horizon.
Yet proceeding south I managed to reacquire it (partially using Lassen as a reference point), and manage to mostly hold it for quite some time. As we were coming up on Chico, it started to get close to disappearing below the horizon. But that never happened. Just north of Chico, Shasta disappeared into blue sky while I was looking right at it. It did not go below the horizon. It was not occluded by any cloud or smoke or smog, nor by trees for that matter. There was no indication of an atmospheric disturbance. I didn't lose its location and fail to require it.
So why might Shasta have disappeared? What limit did I exceed that I could no longer see it?
(safety note: I was not the one driving, so I could indeed turn and look straight backwards for minutes at a time) The reason it disappeared is the same as why the sky is blue: Rayleigh scattering of light from air and small particles in it. When you're close to the mountain its light only travels a short distance through air, so you see it sharply. The further you go away from it the more of its light is scattered. Additionally the light of the mountain is mixed up with light from the sun. If sunlight is scattered towards you at a location of the path between the mountain and your eye it looks like it comes from the mountain (see drawing). The reason why it looks like the mountain becomes mixed with blue is the $\propto \lambda^{-4}$ efficiency of Rayleigh scattering.
The following is multiple choice question (with options) to answer.
All the water vanishes from a small depression basked in sunlight on a paved road because of | [
"freezing",
"evaporation",
"condensation",
"precipitation"
] | B | a phase change is when matter changes from one state into another state |
OpenBookQA | OpenBookQA-1511 | acoustics, vibrations
the solid itself, the air around it too.So the vibrations from one tong of the struck tuning fork travel to the other part via its bulk and set it in motion.
This displacement wave which is set off in the material is the sound that travels through it. This sound reflects off of the object's boundary and traverses across it again and again and so on. In this transient phase, the exact motion is, at least in theory, just the evolution of certain superpositioned normal modes. By design, in case of a tuning fork, eventually the body is left vibrating in just one dominant mode while the energy in most other modes has decayed away faster.
This treatment of analysing transient motion in terms of normal modes(eigenmodes) of interfering sound waves has the benefit that one doesn't have to track down the individual motion of typically $10^{23}$ atoms to make predictions about sound frequency. Only geometry is needed.
The following is multiple choice question (with options) to answer.
audible vibrations can travel freely through | [
"a brick",
"nitrogen and oxygen",
"the ground",
"a mountain"
] | B | sound can travel through air |
OpenBookQA | OpenBookQA-1512 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
An animal needing to be warmer could | [
"starve",
"eat more",
"go out",
"diet"
] | B | fat is used to keep animals warm |
OpenBookQA | OpenBookQA-1513 | machine-learning, classification, decision-trees, information-theory
Weather and Wind both produce only one incorrect label hence have the same accuracy of 16/17. However, given this data, we would assume that weak winds (75% YES) are more predictive for a positive outcome than sunny weather (50% YES). That is, wind teaches us more about both outcomes. Since there are only few data points for positive outcomes we favor wind over weather, because wind is more predictive on the smaller label set which we would hope to give us a rule that is more robust to new data.
The entropy of the outcome is $ -4/17*log_2(4/17)-14/17*log_2(14/17)) =0.72$. The entropy for weather and outcome is $14/17*(-1/14*log_2(1/14)-13/14*log_2(13/14)) = 0.31$ which leads to an information gain of $0.41$. Similarly, wind gives a higher information gain of $0.6$.
The following is multiple choice question (with options) to answer.
If weather is stormy there is a greater chance of what? | [
"drought",
"waterfalls",
"sky water",
"fire"
] | C | if weather is stormy then there is a greater chance of rain |
OpenBookQA | OpenBookQA-1514 | proteins, food, digestive-system, amino-acids, digestion
Title: How are proteins reused in the body? Part of what we eat are proteins,
and our body is in part build of proteins.
Are the proteins of the body build based on proteins in food at all?
Are proteins in food directly reused in the body,
or are proteins first disassembled?
How far are they disassembled, randomly in various pieces, or systematically to keep what can optimally be used to build new proteins, while nothing is wasted for energy?
(The question Can proteins/peptides pass through the intestine? and it's answers are related, and provide some context and relevant parts, but is not a duplicate.) Short answer: Indeed the proteins in our body are based on amino acids from external food sources. BUT, proteins up-taken from food are ALWAYS disassembled first into amino acids, through specialized enzymes, proteases, (for instance Pepsin in the stomach's gastric juices and Tripsin in the pancreatic juices), during digestion, in the alimentary canal, (gut). This enables the body's liver to build the proteins most needed by the organism itself, through the processes of transamination, that allows conversion betwixt amino acids, and deamination, that removes N2 from the amino acid, (let's say the "amino" part is removed, and then expelled as urea), to excrete amino acids in excess. In addition this breaking down of external proteins is necessary, since they can act as labels for pathogens, and external organisms in general, and thus would soon be destroyed by the immune system if reused straight away.
The following is multiple choice question (with options) to answer.
Which recyclable body part is largely comprised of muscle | [
"the ticker",
"the spleen",
"the kidney",
"the liver"
] | A | the heart is mostly made of muscle |
OpenBookQA | OpenBookQA-1515 | c++, game-of-life
void change_state(int, int /* coordinates */, Cell);
bool alive(int, int /* coordinates */) const;
int count_alive_neighbours(int, int /* coordinates */) const;
public:
Species(const grid&);
Species(const Species<size>&);
Species<size>& operator=(const Species<size>&);
void evolve();
template <int samesize>
friend std::ostream& operator<<(std::ostream&, const Species<samesize>&);
};
template <int size>
void Species<size>::change_state(int row, int column, Cell state) {
(*generation_future)[row][column] = state;
}
template <int size>
bool Species<size>::alive(int row, int column) const {
return (*generation_current)[row][column] == Cell::ALIVE;
}
template <int size>
int Species<size>::count_alive_neighbours(int row, int column) const {
const int edge {size - 1};
int alive_neighbours {0};
// Check north
if (row == 0) {
if (alive(edge, column)) ++alive_neighbours;
} else {
if (alive(row - 1, column)) ++alive_neighbours;
}
// Check south
if (row == edge) {
if (alive(0, column)) ++alive_neighbours;
} else {
if (alive(row + 1, column)) ++alive_neighbours;
}
// Check west
if (column == 0) {
if (alive(row, edge)) ++alive_neighbours;
} else {
if (alive(row, column - 1)) ++alive_neighbours;
}
// Check east
if (column == edge) {
if (alive(row, 0)) ++alive_neighbours;
} else {
if (alive(row, column + 1)) ++alive_neighbours;
}
The following is multiple choice question (with options) to answer.
If a thing is living, it will require | [
"noxious foods for illness",
"energetic mutation of limbs",
"a source of happiness",
"a source of nutriment"
] | D | living things all require energy for survival |
OpenBookQA | OpenBookQA-1516 | hvac, heat-exchanger, refrigeration
My limited understanding of heat exchangers is that they operate at a colder temperature that the set point of what they are cooling.
I think that a conventional air cooler would have constant problems with ice forming on the heat exchanger, since even a few degrees colder than the room will be below freezing. I inquired with a company called 'Cool Bot' that has a controller that uses a conventional air conditioner to cool a well insulated room. They agreed that my application would not be suitable due to ice formation.
The second thought is to use a freezer. Chill brine or antifreeze to some cold temperature, and run it through flexible pipe laid directly on the floor. If the floor had a liner so that in effect it was a 3" deep pond, then the seedling boxes can rest on pallets above the pond with the same fan circulating air against the pond.
I don't think a freezer moves enough BTUs for this. Substitute insulated tank + chilling unit. (Old electric water heater for the tank?). Propane tank. (means no salt.)
Now the problem becomes one of control.
My thought is to use a chest freezer outside, verify that it is water proof, and fill it with a solution that won't freeze at a given setting of the freezer. I think I would aim at about -10 to -15 °C. Fill the freezer with the solution. (Brine ok? Freezers inside are made of plastic.)
Run a coolant loop that has some large number of feet of tubing in the freezer with holes drilled in the lid for pass through. (0.700 ID x 1/16" wall thickness black polyethylene plastic is commonly used for irrigation, and is rated at 30 psi. 0.625 water line is rated at 75 psi, but wall thickness is twice the size, which would increase the amount of pipe needed for the same thermal transfer.
Addressing comments:
Precision of temp control
0.5C is a goal. But I have an electronic relay that registers to tenth of a degree, and calibrating it by putting it in a jar in an ice water bath is straight forward.
The following is multiple choice question (with options) to answer.
What's a good way to heat up inside after ice skating on a frozen lake? | [
"Put on a swimming suit",
"set fire to some snow",
"run a cool bath",
"set fire to some natural gas"
] | D | natural gas is a source of heat by burning |
OpenBookQA | OpenBookQA-1517 | homework-and-exercises, fluid-statics
Now picture replacing the red mercury with $13.6\,\rm cm$ of water, and the silver mercury levels stay the same.
The following is multiple choice question (with options) to answer.
Water is a recyclable | [
"commodity",
"lubricant",
"revenue",
"treasure"
] | A | water is a renewable resource |
OpenBookQA | OpenBookQA-1518 | phase
More generically, if one was to apply enough pressure to a gas to make it a solid at room temperature and then remove the pressure, would it stay in the solid form? Instantly? Just like if you go outdoors when the temperature is below zero (centigrade) you freeze instantly? Are you from a location where temperatures never drop below freezing and simultaneously unaware that people live in places where the temperature is below freezing? Otherwise, I can't understand your confusion. Given perfect insulation (which doesn't exist) a material can theoretically maintain its temperature indefinitely. With real world insulation colder materials will slowly warm up, but the rate its temperature increase depends on the quality of insulation. A thermos of a hot liquid can still burn skin many hours after it has been filled. All substance have some ability to insulate, so a liquid or gas can insulate itself (that is can insulate material further away from the heat source). In beginning physical science, you should have learned that a material's temperature is an indication of its energy content. You should also have learned that energy can be neither created nor destroyed; which means that for a material to warm up, energy to do that has to come from somewhere. In terms of heat flow, there are three types of flow: Conduction, convection and radiation. A cup of lox (liquid oxygen) on a table, say, will mostly be warmed by conduction. (Unless you place it under intense lighting or near some other energy source.) As the lox heats up, the table cools down, meaning it will take longer and longer for heat to move into the lox from further away-heat conductivity is slow compared to the speed of light, speed of sound, or even a speeding bullet. (Depending on the shape of the cup, the air above the lox might also supply heat via turbulent flow) One good example of heat flow differences is when you walk barefoot over carpet, it feels warmer that walking over ceramic, wood, or metal even though they are at the same temperature! (or if the surface is hotter than your skin, the carpet will feel cooler than the other surfaces) The heat conductivity (not really related to electrical conductivity!) is faster in metal, and slower in carpet (metal>ceramic>wood) (plastics vary because their composition can be quite different, but organics are generally slower than metals and ceramics (including rock)). As far
The following is multiple choice question (with options) to answer.
What kind of substance will get less warm when it touches a cold object? | [
"a dream",
"ideas",
"cold",
"fresh baked poptart"
] | D | if a hot substance is touches a cold object then that substance will likely cool |
OpenBookQA | OpenBookQA-1519 | java, random
case 2:
return " with little to no vegitation, imports are what this town lives on.";
case 3:
return " and is full of fertile land, the farmers here are prosperous.";
case 4:
return " under the protection of large mountains and rought terrain; lining the horizon.";
case 5:
return " and the visible ocean water laps on the shore gentaly.";
case 6:
return " the visible ocean water is rough, and would be hard to navigate.";
case 7:
return " and strange jagged rocks protrude randomly along the landscape.";
case 8:
return " and purple glows eminate from a very large mountain peak in the far distance.";
case 9:
return " and colourful skys cause the buildings to shine with a great elegance.";
case 10:
return " built partially underground.";
default:
throw new IllegalStateException("Something went wrong!");
}
}
}
The following is multiple choice question (with options) to answer.
A person wants their yard to be a wonderful ecosystem for local wildlife. They consider doing a few things in order to facilitate this, but ultimately decide that the best way to make a great impact is to | [
"make some more money",
"plant a wet rope",
"plant a blue spruce",
"sing to their flowers"
] | C | planting trees has a positive impact on an ecosystem |
OpenBookQA | OpenBookQA-1520 | # Conditional Probability of rainfall
1. Apr 26, 2012
### TranscendArcu
1. The problem statement, all variables and given/known data
3. The attempt at a solution
a) P(Pickwick has no umbrella | it rains) = $\frac{\frac{1}{3}\frac{1}{3}}{\frac{1}{2}} = \frac{2}{9}$, which is the answer according to my answer key.
b) For part b we have:
There is a rain forecast which means he will bring the umbrella. The probability that it won't rain is 1/3.
There is a non-rain forecast which means he brings the umbrella with a probability of 1/3 and it will not rain with a prob of 2/3.
P(Pickwick has umbrella | no rain) = $\frac{1}{3} + \frac{1}{3}\frac{2}{3} = \frac{5}{9}$. But the answer is apparently 5/12. What have I done incorrectly here?
2. Apr 26, 2012
### MaxManus
I got the same as you at b) and I cant see why it is not correct.That's no guarantee for that you are correct though
3. Apr 26, 2012
### Ray Vickson
The following is multiple choice question (with options) to answer.
A person wants to take their dog to the park as long as there is a lack of precipitation that day. After checking the weather channel, plans are canceled when it is announced that it will | [
"be sunny",
"sprinkle",
"be humid",
"be windy"
] | B | precipitation is when water falls from the sky |
OpenBookQA | OpenBookQA-1521 | the-moon, newtonian-gravity
The resultant force looks like this:
Note that the tidal force is away from the center of the Earth when the Moon is directly overhead or directly underfoot, toward the center of the Earth when the Moon is on the horizon, and horizontal when the Moon is halfway between directly overhead/underfoot and on the horizon.
The tidal force is maximum when the Moon is directly overhead, and even then it's only about 10-7 g. You need a sensitive instrument to read that. A simple pendulum or a simple spring will not do the trick.
The following is multiple choice question (with options) to answer.
Invisible forces work to keep the moon near the | [
"sun",
"uranus",
"mars",
"our home planet"
] | D | gravity causes orbits |
OpenBookQA | OpenBookQA-1522 | agriculture
Title: What does "permanent field" mean in agriculture? I am reading a book that in a paragraph talks about the agricultural methods used in prehistoric Finland.
The further north and east, the more extensive the amount of
burn-beat cultivation, which was a far from primitive form of
agriculture. The yield was many times higher (twenty- to thirty-fold)
than on permanent fields (five- to ten-fold), and there were multiple
varieties of the technique
A history of Finland by Henrik Meinander.
One of them is burn-beating. Like I understand, in burn-beating people cut down the trees in the forests and burn the topsoil. This way they can use that soil for 3 to 6 years for cultivation.
The other method is permanent field. I have searched the internet and the result I got was "permanent crops", like here. In which case people planted trees once in a field and harvested them multiple times.
But in another research about prehistoric Finland it was saying:
The site of Orijärvi shows that permanent field cultivation, with
hulled barley as the main crop was conducted from approximately cal AD 600 onwards.
The following is multiple choice question (with options) to answer.
What does crop rotation renew? | [
"plants",
"loans",
"loam",
"water"
] | C | crop rotation renews soil |
OpenBookQA | OpenBookQA-1523 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
Water vapor cooling causes it to what? | [
"electrify",
"warm up",
"deliquesce",
"smell"
] | C | water vapor cooling causes that water vapor to condense |
OpenBookQA | OpenBookQA-1524 | human-biology, cancer, medicine
Title: Why are only few cigarette smokers prone to cancer? It's tacit that only a few populace of smokers get cancer. What spares the others from it or what specifically cause cancer in those populace? See this Washington Post Article Cigarette smokers are most certainly prone to cancer. See Cecil Medicine, Chapter 183, on the epidemiology of cancer, exposure to tobacco is the most important environmental risk factor for cancer development, at least in the US:
Exposure to tobacco is the single largest cause of cancer in the United States... All forms of tobacco can cause cancer. Cigarette smoking causes cancer of the lip, oral cavity, nasal cavity, paranasal sinuses, pharynx (nasal, oral, and hypopharnyx), larynx, lung, esophagus (squamous cell and adenocarcinoma), stomach, colorectum, pancreas, liver, kidney (adenocarcinoma and renal pelvis), urinary bladder, uterine cervix, and myeloid leukemia.
Cancer may be identified or the cause of death in fewer smokers than might be expected, though, because smoking is an even greater risk factor for cardiovascular disease, and death due to cardiovascular disease.
Cancer is an unlikely phenomenon in an individual cell, but becomes more likely at the organism level, and even more likely over time. Though tobacco may be the most important environmental risk factor for cancer, age is actually a stronger predictor of cancer (see again, Cecil Chapter 183. Autopsy studies give us a quite remarkable example, this one shows incidental prostate cancer in nearly 60% of men over 80 who died from other causes. That figure is not out of the ordinary. Live long enough and you are likely to develop cancer.
Death due to heart disease may account for the lower than expected rates of cancer diagnoses and deaths in smokers. Nothing prevents cancer as well as dying from something else. And as discussed in the blog in the Washington Post you linked to, up to 2/3 of smokers die from smoking related causes
The following is multiple choice question (with options) to answer.
smoking will directly affect what? | [
"hearing loss",
"sleep",
"intensity of cough",
"hunger"
] | C | smoking causes direct damage to the lungs |
OpenBookQA | OpenBookQA-1525 | homework-and-exercises, collision
I know that some energy is lost to air resistance and to friction in the bearings and tyres,
Even this just means the energy gets turned into heat somewhere else instead of heat in the brakes.
Earth must have some kinetic energy from the collision no?
Let's say it's a big car, weighing 2000 kg.
The momentum transferred to the earth is
$$p = (30\ {\rm m/s})(2000 {\rm kg})= 60\times 10^3 {\rm kg \cdot m/s}$$
The mass of the Earth is about $6\times 10^{24} {\rm kg}$. So the velocity of the Earth changed by about
$$\Delta v = \frac{60\times 10^3}{6\times 10^{24}}{\rm m/s}=10^{-20}\ {\rm m/s}$$
and the kinetic energy imparted to the Earth was
$${\rm K.E.} = \frac{1}{2}(6\times 10^{24}\ {\rm kg})(10^{-20}\ {\rm m/s})^2=3\times 10^{-16}\ {\rm J}$$
Considering the initial K.E. of the car was about 900,000 J, this energy transfer to the Earth is negligible.
The following is multiple choice question (with options) to answer.
As it travels further into a land mass, what looses power? | [
"a violent disturbance of the atmosphere with high winds",
"ideas in print media",
"a large jet engine",
"a gas guzzling automobile"
] | A | when a hurricane moves over land , that hurricane will decrease in strength |
OpenBookQA | OpenBookQA-1526 | thermodynamics, visible-light, lenses
I forgot to mention that you can't heat the sample beyond about $5500\,K$ (which is the temperature of a black body that best fits the spectrum we receive at sea level). Of course, you need to know what you're doing to get anywhere close to this temperature.
The following is multiple choice question (with options) to answer.
A person is going to explore in the ocean and sees that when they get down to a darker part, | [
"there is more sunlight",
"there is more weight on them",
"there is more salt",
"there is more booze"
] | B | as depth increases , pressure will increase |
OpenBookQA | OpenBookQA-1527 | meteorology, climate-change, gas, pollution
If you are interested in Greenhouse Gases (e.g. methane, carbon dioxide, CFCs, nitrous oxide), the EPA has a separate site for those emissions since they are not part of the same regulatory framework http://www.epa.gov/climatechange/ghgemissions/ . Greenhouse gases typically do not cause adverse health effects for plants or animals on land. However, they have long-term radiative effects (e.g. the greenhouse effect) because they stay in the atmosphere for many years and trap infrared light. These long-term radiative effects are what can change climate and consequently land cover. Furthermore, most of the excess carbon is absorbed by the ocean, which creates carbonic acid. Increased acidity of the ocean causes severe problems for marine ecosystems.
The EPA states that in 2012 the CO2 equivalent GHG emissions for the USA by sector was:
The following is multiple choice question (with options) to answer.
What goes to a place that has a negative impact on the environment? | [
"garbage trucks",
"trains",
"mail trucks",
"motorcycles"
] | A | landfills have a negative impact on the environment |
OpenBookQA | OpenBookQA-1528 | radiation
You see similar things happening here. The metal rod at the top of the lamp acts as a capacitive ground - given the very high voltage, a tiny charge will flow from the tip of the filament to the rod. There is a small amount of gas in the tube which is ionized and gives rise to the light you see. The electrons eventually bombard the metal "anode" and produce Bremsstrahlung - note that without the metal, you were getting a glow and no reading on the Geiger counter. There is a similar demonstration online which is more convincing in its use of conventional materials, but which otherwise shows many of the same phenomena.
It is almost certainly very inefficient. Most of the energy in an X-ray tube is converted to heat as the electrons burrow too deeply into the tungsten target for their radiation to escape- apart from the fact that only the most violent deceleration produces X-rays with high enough energy to penetrate the bulb and be detected.
I noticed that when the "alpha window" was removed, the reading in your video went up. Since there was also a biscuit tin and glass bulb in the way I suspect there was a lot more low energy radiation generated than was detected. Good stuff for skin cancer.
The experiment as shown should not be repeated. Not only were the HV precautions extremely poor, but so were the radiation safety precautions. Please don't try this at home...
The following is multiple choice question (with options) to answer.
A person turns a flashlight on and points it at a cut stone, which results in | [
"flower patterns",
"varied hues",
"varied light scents",
"sizes of elephants"
] | B | refraction is when light bends |
OpenBookQA | OpenBookQA-1529 | zoology
Title: Can my dog really understand me? Are dogs capable to understands human language ( for example after order sit it sit because he know that word) Or can sence our order by body language and intonation if so why this type of communication developed only at dogs? Some researchers say that dogs have the intelligence of a two-year old.
Many dogs can understand more than 150 words and intentionally deceive other dogs and people to get treats, according to psychologist and leading canine researcher Stanley Coren, PhD, of the University of British Columbia.
He is a reasonable and serious scientist who is biased towards overstating dog intelligence. he sais:
The average dog can learn 165 words, including signals, and the “super dogs” (those in the top 20 percent of dog intelligence) can learn 250 words, Coren says. “The upper limit of dogs’ ability to learn language is partly based on a study of a border collie named Rico who showed knowledge of 200 spoken words and demonstrated ’fast-track learning,’ which scientists believed to be found only in humans and language learning apes,”
Dogs can also count up to four or five,
http://www.apa.org/news/press/releases/2009/08/dogs-think.aspx
The following is multiple choice question (with options) to answer.
A puppy was uneducated on how to go through a doggy door until | [
"the mom did it",
"it read how to",
"it went to school",
"it made a plan"
] | A | animals learn some behaviors from watching their parents |
OpenBookQA | OpenBookQA-1530 | java, beginner, object-oriented
protected void removeBook(Book book) {
if(!Library.isBookExist(book)) {
System.out.println("This book is not in the library");
return;
}
Library.getStore().remove(book);
System.out.println("Book: \"" + book.getName() + "\" for the author: " + book.getAuthor() + "is removed from the library");
}
}
public class User extends Action {
private String name;
User (String name) {
this.name = name;
}
public String getName() {
return name;
}
public void changeName(String newName) {
this.name = name;
}
}
public class Admin extends AdminAction {
private String name;
Admin(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void changeName(String newName) {
this.name = name;
}
}
The following is multiple choice question (with options) to answer.
A book experiences tearing so it | [
"has lost status as whole",
"lacks any real mass",
"is completely intact now",
"is a whole book"
] | A | tearing means changing a whole into pieces |
OpenBookQA | OpenBookQA-1531 | electrical-engineering, radiation
As with the cell phone radio, total emissions are very dependent on how busy the radio links are. These are battery powered systems, when not in use they are designed to be as low power as possible. Radio transmitters use a lot of power and so are kept powered down as much of the time as possible.
Finally there are unintended emissions, these are far far lower power than the intentional transmissions but can be measured. All electronic systems emit small amounts of RF energy, the busier they are the more they emit which means anything that uses the phones CPU is causing it to emit a small amount of RF radiation.
Edit -
One minor addition: Connected cables can have an impact (headphones, chargers etc...). While they don't cause any extra emissions directly they can end up acting as antennas and so increasing the efficiency with which the already existing signals are transmitted. This is primarily going to impact the unintentional transmissions but it could also have minor impacts on the intentional transmissions.
The following is multiple choice question (with options) to answer.
A radio that takes batteries can make that energy into | [
"fire",
"video",
"water",
"sound"
] | D | electrical devices convert electricity into other forms of energy |
OpenBookQA | OpenBookQA-1532 | newtonian-mechanics, classical-mechanics, gravity, forces, astrophysics
Title: Universal gravity at small distance Could it be that there is simply a maximum gravitational force that two bodies of finite mass can exert on one another? This would occur at $r=0$, so maybe there is some really really really small $a$ in the universal gravity equation, making it
$$F=G\frac{m_1m_2}{r^2+a}$$
If $a$ was small enough, it would only become apparent at extremely small distances. So as $r$ got smaller, the force would approach it's actual maximum which would be proportional to the two masses rather than just approaching infinity.
Feel free to tell me in layman's terms why that idea is no good, but I haven't had calculus in like 15 years so I doubt I will understand anything too complex. Folks are looking for non-Newtonian gravity. The experimental gravity group at U. Washington have really been the leaders in the field over the past ten years; they have some nice review papers available for free.
Because of the way that short-range forces work in quantum mechanics, we expect that a short-range gravitational interaction would produce a Yukawa potential,
\begin{align*}
\Phi = -\frac{GMm}{r}
\left(
1 + \alpha e^{-r/\lambda}
\right).
\end{align*}
The first term is just the ordinary Newtonian potential. In the second term, $\alpha$ sets the strength of the interaction and $\lambda$ is its length scale. The constraints depend on both $\alpha$ and $\lambda$. As of 2007, it was possible to rule out an interaction with $\alpha=1$ and $\lambda$ > 55 μm.
I expect that the existing data sets constraints on your $a$. If you go to do arithmetic with it, you'll probably want to redefine your $a$ to have units of length rather than length$^2$.
The following is multiple choice question (with options) to answer.
Gravitational force never affects | [
"balloons",
"stars",
"sunshine",
"air"
] | C | gravitational force causes objects that have mass to be pulled down on a planet |
OpenBookQA | OpenBookQA-1533 | heat, earth, geophysics
Title: What if the earth's core goes cold? What effects would occur if the earth's core goes cold? Would the planet stay liveable after this happens? Once the core has solidifed it can no longer generate a magnetic field. There may be some frozen in field, but I would guess that the strength of the magnetic field with decrease as more and more of the core freezes, so any residual field is likely to be small. The core of Mars is thought to be frozen and it's magnetic field is negligable.
Anyhow, the main problem would be that without the magnetosphere to protect it the atmosphere will gradually be stripped by the solar wind and we'll be left with nothing to breathe. In addition, without an atmosphere the surface will be subject to wide temperature swings; just as the Moon is in fact.
So no, by any reasonable definition of the word liveable once the core has frozen the Earth will not be liveable. I wouldn't worry for a while yet though.
The following is multiple choice question (with options) to answer.
What happens to a living thing if it becomes too cold? | [
"pass away",
"joy",
"increased energy",
"warmth"
] | A | if a living thing becomes too cold then that living thing will die |
OpenBookQA | OpenBookQA-1534 | • I am also stuck at this point. If the first rose is $Red$ then the Bride enters the Church and in that case the probability is $\frac{10}{20}$. But now come the cases when the first rose is $White$: $WRR$, $WWRRR$, $WRWRR$ and so on. No matter what, if the first rose is $White$, the last two roses must be $Red$. And the total number of roses required ($\leqslant 20$) to enter the church is $Odd$, where the number of $Red$ roses will never exceed that of the $White$ roses but once when the Bride finally enters the church. Leaves me in doldrums, though. – JackT Oct 18 '17 at 7:42
• @Maths_student Actually, if you have got $x_1$ Red Roses and $y_1$ White roses, then you must get $y_1-x_1+1$ more red roses to enter the church. Or, rather, $x_2-y_2$ should be $y_1-x_1+1$. – MalayTheDynamo Oct 18 '17 at 7:49
• Your edit is incorrect. If she takes a red rose on the first try, she enters, so the probability has to be at least $1/2$ as you said. She can also enter the church if she initially takes a white rose, then takes two red roses in a row. Clearly, the probability is much greater than $1/20$. – N. F. Taussig Oct 18 '17 at 9:34
The following is multiple choice question (with options) to answer.
As a flower becomes more aromatic it will bring in a growing crowd of | [
"lazy tourists",
"leaf miners",
"pollinators",
"caterpillars"
] | C | as the amount of fragrance of a flower increases , the number of pollinators it will attract increases |
OpenBookQA | OpenBookQA-1535 | zoology, species-identification, ornithology, behaviour
Title: What is this crow eating, and is it a common part of the corvid diet? Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:
Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.
What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird? Crows are omnivorous, and will eat almost anything they find or can kill.
In this case the prey looks like a Yellow-Shafted Flicker.
The following is multiple choice question (with options) to answer.
What do hawks eat? | [
"lizard droppings",
"bearded dragons",
"cows",
"grass"
] | B | hawks eat lizards |
OpenBookQA | OpenBookQA-1536 | • Rotterdam apartments for students.
• Injury waiver form.
• Belgian Shepherd for sale Adelaide.
• Yugioh Card search.
• Vincenzo cast Instagram.
• The Grand Hotel entertainment.
• Biosphere 2 Discount Tickets.
• Disco Biscuits sessions.
• Is caviar good for Weight Loss.
• Frosted LED globe bulbs cool white.
• Human faces Drawing.
• Izuku has a horse quirk fanfiction.
• Party Venues with dance floor near me.
• Baby Girl Cowgirl Outfit.
• WordPress homepage settings missing.
• Instagram screen cut off iPhone 12.
• Beaumont children suspects.
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• Izuku has a horse quirk fanfiction.
• MJ'' Harris net worth 2020 Forbes.
• String light Christmas tree DIY.
• Lemon basmati rice in rice cooker.
• Bahamas diving.
• Vinyl Works Pool deck.
• Makelaardij Friesland.
• Neewer Professional Panoramic Gimbal Camera Tripod 360 Panoramic ball head.
• Great Dane breeders in Michigan.
• Don't touch my phone wallpaper scary.
• How to sit with a fractured pelvis.
• Dr Brighten supplements.
• Harry and David promo code.
• How to fit bathroom ceiling panels.
• German Shepherd puppies for sale Wirral.
• Which president annexed texas?.
• Hampshire Garden Centre delivery.
• Helen Keller Pictures of her life.
• How to recover Viber pictures.
• How to fix watercolor painting.
The following is multiple choice question (with options) to answer.
A puppy has a kink in his tail, but he lacked it yesterday. The puppy ______ a broken tail. | [
"inherited",
"absorbed",
"wanted",
"acquired"
] | D | the condition of the parts of an organism are acquired characteristics |
OpenBookQA | OpenBookQA-1537 | meteorology, atmosphere, geophysics, climate, geography
Finally, I have to note that I've interpreted "calmest" as the minimum mean wind speed. However, it would be sensible also to consider it as the place with the lowest maximum wind speed or some other metric, that would perhaps change the picture described above. And maybe using that metric one of the Antarctic domes could be the "calmest" place. But I won't extend the answer further with any possible interpretation for "calmest".
The following is multiple choice question (with options) to answer.
Who would find an arctic environment most pleasant? | [
"iguanas",
"parka squirrels",
"tiger sharks",
"Burmese pythons"
] | B | the arctic environment is cold in temperature from being at a northern lattitude below 0 degrees celsius during most of the year |
OpenBookQA | OpenBookQA-1538 | zoology, species-identification, ornithology, behaviour
Title: What is this crow eating, and is it a common part of the corvid diet? Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:
Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.
What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird? Crows are omnivorous, and will eat almost anything they find or can kill.
In this case the prey looks like a Yellow-Shafted Flicker.
The following is multiple choice question (with options) to answer.
Which animal eats prey? | [
"beetle",
"horse",
"rabbit",
"buffalo"
] | A | predators eat prey |
OpenBookQA | OpenBookQA-1539 | heating-systems
Comparison between the two.
So you can see that, while you use more efficiently the primary energy with the steam boiler, if the electricity you get is from a renewable source then the ceramic might be more environmentally friendly.
Of course, I avoid going into the discussion about carbon emissions, or the total impact on the environment (e.g. consider if your electricity came from nuclear). That makes the problem even more complex.
A Better solution
If you live in a relatively warm climate (i.e. you don't get temperatures under 0 more that a few days per year), a better alternative for electrical power can be a heat pump.
The difference with heat pumps, is that they don't use the electrical energy directly for heating. (Simply put) What they do is they use the electrical energy to mechanically move an arrangement of pumps/compressors/condensors to pump heat energy from one side of the wall to the other. Heat energy that would not usually be inclined to flow towards that direction. More specifically, they take heat from the colder environment and pump it inside a warmer room.
That process, in ideal conditions, is very efficient. For example, for one unit of electrical energy you can nowadays move up to 4 units of heat energy. That ratio of useful energy to energy expended is the basic formula for the famous COP - Coefficient of performance. In this specific example COP would be 4.
So in ideal conditions, if you used 100 units of fossil fuel, and got 35 units of electrical energy, in theory you could get 140 units of heat energy pumped in your room.
Of course, there are limitations. E.g. at cold climates using a heat pump would create ice/frost on the heat pump, which ultimately would lower significantly the COP.
The following is multiple choice question (with options) to answer.
An environmentalist heats their home by using a corn stove. The environmentalist knows that heating this way releases carbon dioxide back into the air, but is unworried about is as a result of | [
"it promoting plant growth",
"corn is too dangerous",
"corn is actually evil",
"corn grows under the water"
] | A | biofuel releases carbon dioxide into the atmosphere |
OpenBookQA | OpenBookQA-1540 | thermodynamics, phase-transition, states-of-matter
So in theory, you can have 100% ice that is at melting temperature. If you apply exactly the energy required for that amount of ice to transition to water, then you would have 100% water that is at the exact same temperature. If instead you only applied 50% of the energy required to melt that quantity of ice, then you would have a mixture of 50% ice and 50% water, still at the same temperature. (Of course in reality the temperature will not be perfectly even; you're much more likely to have ice at a range of temperatures from just below up to the melting point and water at a range of temperatures from the melting point to a bit above)
So there's a clear boundary in that each given "bit" of H2O is either water or ice, there's no state that is "in between ice and water" that is passed through on the way to melting the ice. The halfway point to melting a block of ice does not have all of the ice with "partially weakened bonds", or anything like that. But the transition of a large chunk of ice into water is a gradual process, not something that happens at a clear instant - more of the ice gradually undergoes the (sharp) transition to water as more energy is gradually added.
The following is multiple choice question (with options) to answer.
melting ice may be formed by | [
"the moon",
"temp change",
"an iceberg",
"a reaction"
] | B | temperature changing can cause phase changes |
OpenBookQA | OpenBookQA-1541 | optics, geometric-optics, lenses
I found a hand magnifier whose focal length was approximately $5$ cm and set it up to be about $4$ cm from the lens so that the virtual image would be about 25 cm from the lens.
I then put another grid 25 cm from the lens as shown in the photograph.
What was pleasing was that the iPhone simultaneously brought into focus the grid viewed through the lens and the grid 25 cm below the lens.
Note that the grid 4 cm from the lens was out of focus and "bigger" than the grid 25 cm from the lens.
If I had used that as my direct view grid as the reference the magnification found would have been in error.
10 magnified small squares were equal to 63 unmagnified small squares which gave a magnification of approximately $6$ which is not bad when compared with the theoretical value of $\frac {25}{4} \approx 6$.
So perhaps it is worth having another go at measuring the magnification of your $12$ cm lens noting that it is not only the focal length but the optical configuration which determines the magnification?
Later
The magnification $M$ of a magnifying glass is defined as
$$M = \dfrac{\text{angle subtended by image of object when 25 cm from the lens}}{\text{angle subtended by object when 25 cm from the naked eye}} = \dfrac {\alpha '}{\alpha}$$
The HyperPhysics article Simple Magnifier gives some more theory.
The following is multiple choice question (with options) to answer.
A magnifying glass makes objects | [
"more clear",
"smaller",
"spontaneous combust",
"physically grow"
] | A | as the size of an object appears larger , that object will be observed better |
OpenBookQA | OpenBookQA-1542 | brain, exercise
Neuromodulators are involved in a variety of processes including pain
modulation, reward, response to stress, and autonomic control.
In humans, acute exercise causes significant increases in peripheral
levels of endogenous opioids; this effect is intensity-dependent,
corresponds to acute exercise-induced changes in HPA axis hormones,
and is linked to improvements in mood.
Though the endogenous opioids have received much attention in terms of
their involvement in the “runner’s high”, scientists are beginning to
understand that endocannabinoids may be equally or perhaps more
involved.
Other sources:
Effects of physical exercise on anxiety, depression...(Clinical Psychology Review, 2001):
Acutely, emotional effects of exercise remain confusing, both positive
and negative effects being reported.
...or as Alex Corb, PhD says in Boosting Your Serotonin Activity (Psychology Today):
Interestingly, if you try to do too much exercise, or feel forced into
doing it, it may not have the right effect. Recognizing that you are
choosing to exercise changes its neurochemical effect. That may be a
result of your ancient instincts — the difference between running
because you're hunting something, and running because it's hunting
you.
How to increase serotonin in the human brain without drugs (Journal of Psychiatry & Neuroscience, 2007):
Exercise improves mood in subclinical populations as well as in
patients. The most consistent effect is seen when regular exercisers
undertake aerobic exercise at a level with which they are familiar.
The following is multiple choice question (with options) to answer.
positively impact your bodies strength by | [
"dead-lifting",
"thinking",
"sleeping",
"singing"
] | A | exercise has a positive impact on a body 's strength |
OpenBookQA | OpenBookQA-1543 | botany, reproduction
Most new commercial tomatoes, including new garden tomatoes, are F1 hybrids. The seeds you plant in the field are the result of crossing two parents, as described above. (...) Garden catalogs will tell you whether the seed you are buying is hybrid. If you are getting your fruits from the store, you can count on them being hybrids unless they are marked as heirloom.
The following is multiple choice question (with options) to answer.
You might support a growing tomato plant with | [
"yard stick",
"a bench",
"a flashlight",
"candy"
] | A | a stem is a source of support for a plant |
OpenBookQA | OpenBookQA-1544 | matter
When a solid is dissolved in a liquid, is it still a solid
I want to touch on this too, because there's a useful subtlety here.
When you put salt in hot water, it dissolves. In this case the energy from the water is enough to overcome the attraction between the atoms, and it is pulled off the crystal to mix with the water. So you don't have water and salt any more, you have a mixture of Na ions, Cl ions, and water molecules. Or saltwater.
Now compare this to what happens when you salt and sugar. In this case the two happily sit together as a mixture, but they are not changed in form. They're also quite tasty, as salted caramel attests. If one of the two you mix is a liquid, like powder in water, then you have a suspension. In these cases the original materials remain in their original forms, just mixed together. This is different than the saltwater case, which is not simply salt and water in the same bottle.
The following is multiple choice question (with options) to answer.
Salt dissolves better in a pot of water after | [
"drowning in the Atlantic ocean",
"setting the burner to maximum",
"setting the burner to minimum",
"gargling salt-water in the shower"
] | B | as temperature increases , the ability of that liquid to dissolve solids will increase |
OpenBookQA | OpenBookQA-1545 | civil-engineering, construction-management
Title: Why use two tower cranes on one construction site? I am fascinated by construction. My university is building a new facility, and they are using 2 tower cranes in the construction.
Why would a contractor choose to use 2 cranes on one construction project? Is it simply a matter of saving time by having the two cranes work simultaneously? What are some other considerations that might be taken into account?
EDIT: after checking your answers, I agree that it is most likely that using two cranes in this situation was mostly done to increase productivity/throughput, and the positioning of the cranes depends on the building design and ease of loading materials to be transported by the crane. Tower cranes are a very significant cost on any construction site, and so builders will usually only use as many cranes as is necessary.
I work for a construction scheduling company, and the one of the biggest factors for deciding on the number of cranes and their location is access. Obviously the crane needs to be able to access all parts of the building during construction, but the placement of the crane is also often determined by access to roads and materials on the ground. Other big restrictions such as site boundaries and roads also often come into play in urban areas. If the access limitations mean you need two cranes, then two cranes will be used.
Secondly, as you noted, is time. Time is money on a site, and if having a second crane can save you a couple of months off your finish date, then it is usually a cost effective idea. Other times, there may be a hard deadline for a project finish, in these cases more than one crane may be used to accelerate the program at the request of the client despite it being more expensive.
The following is multiple choice question (with options) to answer.
A construction team is building a business center where a park used to be. The change in the park will | [
"cause animals to play",
"cause animals to celebrate",
"cause animals to marry",
"cause animals to suffer"
] | D | humans changing animal habitats usually causes harm to those animals |
OpenBookQA | OpenBookQA-1546 | Bridge Mountain Climb, Malvan Village Ghost Story, Graham Greene Rdr2, Bd Script Font Canva, Vintage Toy Tractor Price Guide, Software Developer No Experience, Fire Pit Insert Round, Classroom Leadership Pdf, Police Officer Hard Skills, How To Separate Succulent Arrangement,
The following is multiple choice question (with options) to answer.
Meadow vales are | [
"carnivores",
"hard of hearing",
"very large",
"potatoes"
] | B | meadow voles eat plants |
OpenBookQA | OpenBookQA-1547 | climate-change
Source: World Meteorological Organization Press Release No. 976: 2001-2010, A Decade of Climate Extremes
The above image speaks for itself. The global temperature change over the last forty years is very real, and is not noise.
With regard to point #2, yes the climate has changed in the past, and by huge amounts. We've had everything from snowball Earth to dinosaurs roaming the Arctic. And the point is? This argument is akin to a farmer taking a trip to the Grand Canyon and upon seeing what damage nature can do decides to forgo contour plowing and other anti-erosion farming techniques.
That the farmer's field might turn into a mountain or be washed out to sea several millions of years from now is irrelevant. What's relevant is that his good or bad practices have an impact on the world food supply. That nature can do far worse does not negate those bad farming practices. Bad farming practices are bad for humanity.
Getting back to climate change, if higher global temperatures are bad for humanity, it doesn't matter matter one bit how close ice came to the equator or how far north dinosaurs roamed in the past. What matters is that modern humanity is sensitive to climate change, be it natural or induced by humans.
With regard to point #3, yes, weather becomes chaotic after ten days or so. That does not mean that climate is chaotic, and if it is, the ~ten day Lyapunov time of the weather does not mean that climate also has a ten day Lyapunov time.
With regard to point #4, it is CO2. It was amusing to follow the skeptic response to Richard Muller's Berkeley Earth Surface Temperature project. Muller was a self-proclaimed skeptic, and he was going to prove those leftist climatologists wrong. The skeptic community cheered at the start.
"He's going to prove them wrong!" A funny thing happened on the way to proving them wrong: He proved them to be correct. Muller was an honest scientist in this regard. His own work caused him to switch from being a skeptic to ascribing to AGW.
The following is multiple choice question (with options) to answer.
There are many protests and outraged people about humans changing the environment of the rain forest because changing even something small in an environment can | [
"wreck it",
"make it cry",
"make it laugh",
"do nothing"
] | A | humans changing an environment sometimes causes that environment to be destroyed |
OpenBookQA | OpenBookQA-1548 | = ",Count[Drop[branches,gen],_Real,\[Infinity]]/4" "" ""Length = ",SetAccuracy[Count[Drop[branches,gen],_Real,\[Infinity]]/4*(Norm[{{pt1[[1]],0.5},{0,0}}]^gen),3]}],18],Gray],{2.3,-1.8}]},{Inset[Style[Text@TraditionalForm@Style[Row[{"Polynomial Trees by Bernat Espigulé"}],18],Gray, Opacity[0.4]],{2.3,-2}]}},PlotRange->{{-1.7,3.7},{-2.1,1.5}},ImageSize->{1000,600},Background->Black]],{{th,0.025,"Thickness"},0.005,0.185},{{gen,12,"Generations"},Range[1,16], ControlType -> SetterBar},{{pt1,{0.5,0.5}},{-0.5,0.5},{0.5,0.5},Locator}]Jurassic Trees
The following is multiple choice question (with options) to answer.
A tree must depend upon, for its support | [
"A large fibrous mass",
"plants on the forest floor",
"the wooden welfare state",
"massive redwoods on the backs of turtles"
] | A | a trunk is a source of support for a tree |
OpenBookQA | OpenBookQA-1549 | explosions
Title: What will happen to you if you're standing near exploding TNT bomb near 20meter away in Vaccum? What I think here could be ,that we'll feel less powerful shock wave as there is no medium of air through which gases can travel . If their is any other possibilities than please suggest ! You'll want to add some numbers to your question if you want someone else to do some calculations.
For a simple answer:
In a vacuum
Sound does not travel so you wouldn't suffer overpressure damage to the same extent, though depending on the size of the explosion it could fill the vacuum and increase the pressure enough to kill or injure you.
Any shrapnel will travel faster in a vacuum, doing more damage.
" ... Outer space explosions tend to manifest a spherical 'cloud', reminiscent of other space-based explosions ...".
Underwater (opposite situation)
Sound travels far, and pressure a short distance, resulting in a bubble pulse.
Shrapnel won't travel very far.
Direct contact of an exploding device enhances the explosion because the pressure of the water helps direct the explosion towards the most forgiving direction (you, or a sub).
In your case the combination of air and vacuum is closer to the 'all vacuum' example rather than the opposite 'underwater' example. It depends upon what numbers we are talking about whether 20 meters makes a difference, as does the extent of the vacuum and composition of the container.
A huge explosion will create plenty of vacuum. Small explosions are used to protect against explosions in the Iron Curtain or explosive reactive armor methods of tank protection.
The following is multiple choice question (with options) to answer.
Explosions destroy | [
"Air",
"communities",
"darkness",
"Sunlight"
] | B | explosions can cause harm to an organism |
OpenBookQA | OpenBookQA-1550 | speed of the car in miles per hour? what dimensions should he use? Custom Solutions. Find the fraction. Find the fraction. Given : This year, the chickens laid 30% less eggs than they did last year and they laid 3500 eggs this year. This was$14 less than twice what she spent for a blouse. So, the chickens laid 5000 eggs last year. Since in one year the man will be six time as old as the daughter is now, the man's present age is. Time and work word problems. … So, the three angles of a triangle are 60°, 72° and 48°. Find the number. Get help with your Math Word Problems homework. Phone support is available Monday-Friday, 9:00AM-10:00PM ET. Given : Difference between x and âx = 12. x = 9 does not satisfy the condition given in the question. Stay Home , Stay Safe and keep learning!!! Let x be a …, Applications: Number problems and consecutive integers Sum of 3 consecutive odd integers is -3, what are the integers? Basic-mathematics.com. Then the length of the rod 2 meter shorter is (x - 2) and the total cost of both the rods is $60 (Because cost would remain unchanged). If 18 be subtracted from the number, the digits are reversed. Let x, then, be how much she spent for the blouse. The fourth part of a number exceeds the sixth part by 4. Math Word Problems with Answers - Grade 8. In this problem, it is the price of the blouse. A number consists of three digits of which the middle one is zero and the sum of the other digits is 9. Elsa used her card only once to make a long distance call. MathHelp.com. These word problems worksheets are a good resource for students in the 5th Grade through the 8th Grade. Apart from the stuff given above, if you need any other stuff in math, please use our google custom search here. Sign up today! To solve word problems in algebra, start by reading the problem carefully and determining what you’re being asked to find. Step 1:: A problem involving work can be solved using the formula , where T = time working together, A = the time for person A working alone, and B = the time for person B working alone. Given : Sum of the reciprocals of the parts is 1/6. Let
The following is multiple choice question (with options) to answer.
A guy wants to figure out how fast makes it to work every day so he looks up | [
"how wide the road is",
"how tall the building is",
"how the weather is",
"the space between destinations"
] | D | calculating speed requires knowing distance travelled |
OpenBookQA | OpenBookQA-1551 | electric-circuits, potential, electrical-resistance, conductors
These analogies are not exact and are only intended to give you a better feel as to what is happening.
Hope this helps.
The following is multiple choice question (with options) to answer.
An example of an electrical circuit could be | [
"Dimming the lights",
"Driving a car",
"Drinking water",
"Riding a bike"
] | A | a light bulb converts electrical energy into light energy when it is turned on |
OpenBookQA | OpenBookQA-1552 | entomology
Title: What is the name of this tiny creature? It looks like a tiny piece of moving cotton? By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name? From your image, it looks like it might be a woolly aphid. I just did a bit of cursory research, and it looks like they're often described as floating pieces of fluff, that seem to wander instead of directly heading somewhere. The fluff on their back is actually wax produced as a defense mechanism from predators and the like. I hope this is what you were looking for!
The following is multiple choice question (with options) to answer.
A tiny sand particle came from | [
"another world",
"boiling water",
"candle fragments",
"larger mineral chunks"
] | D | sediment is formed by weathering |
OpenBookQA | OpenBookQA-1553 | Apply this under both cases (500lbs and 200lbs) you should get your ans
• October 13th 2009, 10:03 AM
Soroban
Hello, fifthrapiers!
Quote:
If 15 workers can pave 18 driveways in 24 days,
how many days would it take 40 workers to pave 22 driveways?
It helps if you understand the "algebra" of these work problems.
$\begin{array}{cccc}\text{We have:} & \text{15 workers} & \text{18 driveways} & \text{24 days} \\ \\
\text{Divide by 15:} & \text{1 worker} & \frac{6}{5}\text{ driveways} & \text{24 days} \\ \\
\text{Multiply by 40:} & \text{40 workers} & \text{48 driveways} & \text{24 days} \\ \\
\text{Multiply by }\frac{11}{24}\!: & \text{40 workers} & \text{22 driveways} & \text{11 days}\end{array}$
• October 13th 2009, 10:34 AM
fifthrapiers
THANK YOU ALL!!
Soroban, I especially like your method. I tried it for the second one...
20 pigs ... 500 lbs mush ... 7 days
We want to get to:
14 pigs ... 200 lbs mush ... x days
So, we alter the first set to try get the second set (my question is can I alter any 2 numbers? In this case it worked):
First we will get down to 14 pigs (multiply by 14/20):
14 pigs ... 350 lbs mush ... 7 days
Then, we get 350 lbs mush down to 200 lbs mush (multiply by 200/350):
14 pigs ... 200 lbs mush ... 4 days
!
So I can always just alter 2 numbers? Like I could multiply the above and alter days/pigs? That's awesome.
• October 13th 2009, 10:59 AM
fifthrapiers
I think I realized something. Another problem was: If 4 boys can shovel a driveway in 2 hours, how many minutes will it take 5 boys to do the same job?
The following is multiple choice question (with options) to answer.
A thousand new trucks are put on the road carrying produce. As a result | [
"distant cities burn down",
"things stay the same",
"distant locations build quarries",
"distant locations have greater produce options"
] | D | as ability to transport food increases around the world , the available types of food in distant locations will increase |
OpenBookQA | OpenBookQA-1554 | temperature, sun, light, equator, insolation
Title: Why does the intensity of sunlight depend on your latitude? People at the equator get to bask in more sunlight than Santa Clause and other inhabitants of the arctic regions. Not quite as pronounced, but they get more than me too.
Why is the sunlight more intense closer to the equator and less intense farther away from it?
When I posted this question, I was not thinking about the possible ambiguities, such as "Are you talking about the exposure across a surface area with some non-perpendicular angle to the sun," or "Are you talking about the light gathered by an optic facing the sun?" There is a difference. Since "basking in sunlight" was the example use case, let us assume exposure across a surface area which is lying on the ground. As noted in the comments, this answer applies to things like sun-bathing and solar panels, but it does not apply so much to a specific point-receptor like an eyeball. If all objects in question are pointing directly at the sun, then the angle of incidence is equal for all of them and this answer does not apply.
For an optic facing its target, the amount of atmosphere that the light passes through is a very large influencer. At higher latitudes, the sun is not directly overhead, and so the light is not coming straight down through the path of least atmosphere. Instead, it comes in at an angle, passing through more of the atmosphere before it gets to you.
For sun-bathers, solar panels, and the ground in general, the sunlight absorbed and reflected does depend very much on what is described in this answer. For that reason, more expensive solar panels are mounted on devices which alter their angle to face the sun for increased light exposure. And a sun-bather could likewise increase their exposure by mounting their platform at an angle. This is the direction the rest of the answer will take.
The answer is similar to the answer to some other questions, such as "Why does the solar power intensity change with the season?" and "Why does the solar intensity change with the height of the sun in the sky (ie: with the time of day)?"
The very short, non-technical version (tl;dr)
Each unit (think "beam of sunlight") is spread over a larger area.
That might not seem intuitive at first, but that is the answer in a nutshell. To see why, continue to the long version.
The following is multiple choice question (with options) to answer.
Palm trees use the sun to | [
"swim",
"eat",
"sleep",
"run"
] | B | In the food chain process some types of plankton have the role of producer |
OpenBookQA | OpenBookQA-1555 | measurements, data-analysis
Practically speaking, however, all real mediums of communication require the size of the string to be bounded. If you have 40 pages in a journal article to describe your results, you only have 120000 characters to capture your result (assuming roughly 3000 characters per page). This can only describe $26^{120000}$ possible outcomes, assuming the alphabet from A-Z. If there are 3 trillion trees on earth, and 20,000 pages can get produced from each tree, and you permit all of unicode ($2^{16}$ characters) rather than just A-Z, and you use all of them up for your paper you can get $2^{960,000,000,000,000,000}$ possible outcomes, which is gargantuan, but still a far cry from infinity.
It can be shown that you can develop a string to encode any real number, while still being able to do all integer arithmetic without violating any rules. However, you can't encode every real number at the same time with this trick. You have to pick the real number, and then build the system around it. In science, constructing your measurement scheme around the result after the result is acquired is considered to be poor form.
Accordingly, all physically realizable experiments map any countably infinite values into a finite space, if for no other reason than to provide a way to actually write the results down. There are, of course, plenty of other reasons to do this mapping, but this particular one is the easiest to argue from a information theory perspective.
The following is multiple choice question (with options) to answer.
Tectonic expression can give massive amounts of data to a | [
"seismograph",
"lie detector",
"geiger counter",
"glass of water"
] | A | a seismograph is a kind of tool for measuring the size of an earthquake |
OpenBookQA | OpenBookQA-1556 | electromagnetism, energy, electric-current
Title: Where does the energy of the electric cable come from? I'm stuck on one really simple example, I can't figure out what's happening to energy here...
(This is not homework)
Let's consider an uncharged electric cable, we'll model it by an infinite cylinder on the axis $(Oz)$ with radius $a$ and conductivity $\gamma$ with uniform, constant current $I$, and we'll obviously use cylindrical coordinates $(\vec{e_r},\vec{e_\theta},\vec{e_z})$.
If I haven't made any mistake, we should have the electric and magnetic fields $\vec{E},\vec{B}$ as follows :
$\vec{E}=\begin{cases}\frac{1}{\gamma}\frac{I}{\pi a^2}\vec{e_z}&r<a\\\vec{0}& r>a\end{cases}$,
$\vec{B}=\begin{cases}\frac{\mu_0I}{2\pi}\frac{r}{a^2}\vec{e_\theta}&r\le a\\\frac{\mu_0I}{2\pi}\frac{1}{r}\vec{e_\theta}&r\ge a\end{cases}$
Thus the poynting vector $\vec{\Pi}=\begin{cases}\frac{-r}{2\pi^2\gamma a^4}I^2\vec{e_r}&r< a\\\vec{0}&r> a\end{cases}$
The following is multiple choice question (with options) to answer.
what is an electrical energy conductor? | [
"plastic",
"stone",
"plants",
"swords"
] | D | metal is an electrical energy conductor |
OpenBookQA | OpenBookQA-1557 | rocks, remote-sensing, archaeology, ground-truth
Together, #1, #2, and #3 tell us that it's probably early summer just after the river ice has broken up.
The tooth-like features in the left image are simply erosional remnants sticking out of the riverbank. They could be bedrock (not likely), ice wedges, unmelted permafrost, or simply dirt. They are on the outside of a meander, so the river is actively cutting into them, and so the river-facing faces are quite sheer and high compared to the slopes in between. The right side might be white because the conditions there had left the snow unmelted when the image was taken. And of course their shadows are longer because the river channel is at the bottom of the bluff.
If you use Google Maps or Earth to go downriver a bit (up and to the left), you will see similar features sticking out of the riverbank, but because they're at a different angle from the features in your image, the fact that they're natural is more readily apparent.
Although the terrain is much less regular on the right side of the image, again the long shadows tell the tale. There are some round lumps that may be pingoes. The shadow that looks like a man is just a coincidental jumble of shadows from the broken terrain. If you look closely at the lump that is supposed to be the "man" (which would technically be an inunnguaq) does not have any protrusions that correspond to the "arms". The "arms" are the shadow of a little cliff or shelf past the lump, which is overlapped by the lump's larger shadow.
It's similar in effect to the infamous misinterpretation of a Viking orbiter image of a natural feature on Mars as a "Face on Mars".
This is a good example of the complications of image interpretation, specifically, understanding the conditions under which the image was taken. It's also a good time to emphasize the importance of doing ground truth when interpreting images. So when you go there, let us know what you find.
The following is multiple choice question (with options) to answer.
A mountain is shoved skyward one day, so there must have been | [
"a clone",
"an emission",
"a flood",
"a mistake"
] | B | mountains are formed by volcanoes |
OpenBookQA | OpenBookQA-1558 | Kudos [?]: 4 [2] , given: 0
Re: Good set of PS 2 [#permalink] 19 Oct 2009, 08:02
2
KUDOS
Bunuel wrote:
4. A contractor estimated that his 10-man crew could complete the construction in 110 days if there was no rain. (Assume the crew does not work on any rainy day and rain is the only factor that can deter the crew from working). However, on the 61-st day, after 5 days of rain, he hired 6 more people and finished the project early. If the job was done in 100 days, how many days after day 60 had rain?
(A) 4
(B) 5
(C) 6
(D) 7
(E) 8
This one was solved incorrectly:
Days to finish the job for 10 people 110 days.
On the 61-st day, after 5 days of rain --> 5 days was rain, 55 days they worked, thus completed 1/2 of the job, 1/2 is left (55 days of work for 10 people).
Then 6 more people was hired --> speed of construction increased by 1.6, days needed to finish 55/1.6=34.375, BUT after they were hired job was done in 100-60=40 days --> so 5 days rained. They needed MORE than 34 days to finish the job, so if it rained for 6 days they wouldn't be able to finish the job in 100(40) days.
I solved in a more easier way I think:
1) 10 man 110 days --> need for 1100 man.days
2) 55 days with 10 men --> 550 man.days
3) 40 days with 16 men --> 640 man.days
--> total man.days equals 1190 vs need for 1100 --> days of rain equals 90/16 max --> 5.625 --> rounded to 5
Senior Manager
Joined: 31 Aug 2009
Posts: 420
Location: Sydney, Australia
Followers: 6
Kudos [?]: 165 [1] , given: 20
The following is multiple choice question (with options) to answer.
Rain helps | [
"candy",
"communities thrive",
"cooking",
"bread"
] | B | rain is a source of water |
OpenBookQA | OpenBookQA-1559 | 51. Trisaba
thanks for the help
52. dan815
|dw:1441062793507:dw|
53. dan815
this is the full break down
54. dan815
they will probably ask u a final question like the chance it will rain, when there is a prediction of rain
55. Trisaba
60%
56. Trisaba
bayes' theorem
57. Trisaba
thanks for helping dan
58. dan815
wait i got 36% lemme see
59. dan815
okay think about it like this out of every 97 days, 5% of those days say it will rain, and it wont rain out of every 3 days, 90% of those days say it will rain, and it will rain! what is the total number of days it will rain to not raining then?
60. Trisaba
61. dan815
0.03*0.9 : 0.05*0.97 this means that (0.03*0.9)/((0.03*0.9)+(0.05*0.97)) = chance it rains when it say it rains
62. Trisaba
60% is what i got
63. dan815
what did u say p(b) was
64. Trisaba
P(B) is .0755
65. Trisaba
look at my sheet posted pic
66. dan815
hard to read, what did u say P(B|A) was then
67. Trisaba
.9
68. Trisaba
$\frac{ 90 }{ 151 }$
69. Trisaba
it rounds to 60%
70. dan815
hmm i am not seeing anything wrong with the way im finding the answer, ill think about this more later but for now for every 100 days 3 days really rain 90% of 3 days is 2.7 so every 2.7 days out of the 3 days it rains, it will predict right now an additional bad predictions of 5% of 97 days is thrown in there 0.05*97=4.85 right preiction and rain = 2.7 total prediction of rainy days = 4.85+2.7 therefore 2.7/(4.85+2.7)= ~36%
71. Trisaba
|dw:1441064489549:dw|
72. Trisaba
The following is multiple choice question (with options) to answer.
Rain at the apex of a pyramid will end up | [
"on your shoes",
"on the side",
"at the footing",
"at the top"
] | C | water flows down a slope |
OpenBookQA | OpenBookQA-1560 | fluid-dynamics, flow
Title: Where does the air go behind a wind turbine? A wind turbine receives wind at 10m/s, and slows it to 5m/s to generate electricity.
Does this mean that the wind around the turbine must be diverted to allow twice the cross-section area for the exiting wind?
If not, how does the exiting air escape? To preserve continuity of mass flow across the propeller disc, the slower air exiting the disc downwind swells out to produce a slow-moving wake that is wider than the propeller disc itself. This gets mixed up with the surrounding air and eventually the wake dissipates as the air in it speeds up to match the surrounding velocity.
The following is multiple choice question (with options) to answer.
a windmill converts wind energy into | [
"food",
"music",
"architecture",
"charged electrons"
] | D | a windmill converts wind energy into electricity |
OpenBookQA | OpenBookQA-1561 | photosynthesis, botany
Title: Photosynthesis - Light Intensity Say I was conducting an experiment for photosynthesis. If I moved light closer to the plant, what effect would this have on the process of photosynthesis? The rate of photosynthesis varies from plant to plant. Some plants require more light and some require less. If you move light closer to the plant, in most scenarios the rate of photosynthesis is likely to be increased. For some plants a minimal light is enough for their photosynthesis, so for those plants, moving light source closer or further will have less effect.
The following is multiple choice question (with options) to answer.
If a plant is going to photosynthesize, it can have all aside from | [
"water",
"sunlight",
"cake",
"soil"
] | C | a plant requires sunlight for photosynthesis |
OpenBookQA | OpenBookQA-1562 | So by my equation I get that they are of equal purity.
Kalyan.
4. ## Re: Purity
Hello, PASCALfan!
Two vessels contains equal amount of water and beer.
1 spoon beer is added to the water and mixed well.
From this mixture 1 spoon is added to the beer.
Which of the liquids is more pure?
This is the classic "Wine and Water" problem.
As long as the amount transferred each time remains the same,
. . the final concentrations are equal.
This is the basis of a stunning card trick.
You are seated at a small table across from your volunteer.
You show him a deck of cards, fanning them
. . so he can see they are all facing one way.
Both of you place your hands under table.
You hand him the deck.
Instruct him to select a secret number from 1 to 20,
. . and keep it a secret. .Call it n.
Have him count off the top n cards,
. . turn them over and replace them on the deck.
Have him shuffle the deck thoroughly.
Then count off the top n cards
. . and hand them to you under the table.
Now you remind him:
. . you don't know his secret number,
. . he doesn't know how many face-up cards he has,
. . you don't know how many face-up cards you have.
Despite this, you will try to make your number of face-up cards
. . equal his number of face-up cards.
He hears the sound of cards being counted and moved.
After a few moment, you bring your cards to the top of the table
. . and count the face-up cards.
Instruct him to do the same . . . and the numbers match!
[Acknowledge the thunderous applause ... modestly, of course.]
Spoiler:
Secret: When he hands you the packet, turn it over.
5. ## Re: Purity
In fact, the answer does not change regardless of how well the liquids were mixed in the process. Indeed, the volume of the liquid in each vessel after the two operations is the same as it was initially. Therefore, in the end the volume of beer in water has to equal the volume of water in beer.
This is one of my favorite math problems because it shows that there is more to math than handling large formulas.
6. ## Re: Purity
Thanks for the card trick..
Regards
The following is multiple choice question (with options) to answer.
A person has a glass of water and a friend pranks them by making their water taste different. They prankster added | [
"ice",
"water",
"soda",
"air"
] | C | dissolving a substance in water causes the water to taste like that substance |
OpenBookQA | OpenBookQA-1563 | electromagnetism, magnetic-fields, history
Title: What this thing is and what it's used for? Images:
I'm not sure if this is the right stackexchange to ask this question but i haven't found a "gas display detection and measuring devices" stackexchange so physics seems like a somewhat reasonable place to ask.
I've found something looking like a chandelier i'm supposed to sell online on my job and i have no idea what it is used for, all i can gather is that there are three compasses that function and that can be locked in place with a small lever. the outside of the wooden box says:
"Hermann Sewerin
Vorm. Vulkan-Werk GMBH
Gaspatex(R)
Gütersloh i. Wf.
Gas-Anzeige-Spür- und Messgeräte"
Meaning gas display detection and measuring devices from a german manufacturer of such devices.
Thanks for any help, or for pointing me in the right direction to ask. that thing indicates the magnetic field strength emanating from a tube carrying a current of electricity through the hole in the center of the device. it is an antique and hasn't been used for this purpose for probably 75 years.
The following is multiple choice question (with options) to answer.
A green container with white arrows in a circle indicate it's a receptacle for | [
"trash that can be used for a new purpose",
"excess and unused portions of soylent green",
"radioactive nuclear waste materials",
"hazardous biological materials and waste"
] | A | recyclable means a material can be recycled |
OpenBookQA | OpenBookQA-1564 | • I think the gif dosn't really fit this site, though I can't say if there is a specific rule against such things – Yuriy S Oct 10 '16 at 11:27
• @YuriyS: Hmm ... I am sorry to learn that people may find it inappropriate! That was by no means my intention! Do you think it would work better by removing the gif an leave the link and the figure of speach, or are all of those opfuscating the points I tried to make? – String Oct 10 '16 at 12:21
• @String: your link to a cartoon movie of a dead animal being bludgeoned is disproportionate and offensive. – Rob Arthan Mar 12 '17 at 1:27
• @RobArthan: Sorry, in some parts of the world such a cartoon would be considered merely a funny way to illustrate the saying about beating a dead horse. No offense intended, only a light tone. I cannot help that people do take offense, so I have removed it. Still it puzzles me how a cartoon matching the content of a saying would offend. I am from Denmark, after all. – String Mar 12 '17 at 8:11
• @String: on MSE it's easier just to use neutral language. As I am English (after all), may I point out that the cliched phrase is actually "flogging a dead horse" and it doesn't have the connotations you think it does (it's not "explaining to death", it's using a tired old argument that has lost all interest or relevance). Your cartoon doesn't help with that. – Rob Arthan Mar 13 '17 at 1:55
1. Well... yes... it does break down. You assumed that there are only 6 primes and reached a contradiction. You've successfully proved that there aren't only 6 primes.
2. Under the assumption that there are only 6 primes 30,031 isn't factorizable.
The following is multiple choice question (with options) to answer.
A dead skunk in the middle of the road would be most appealing to | [
"a giraffe",
"a politician",
"a vulture",
"a whale"
] | C | scavengers eat dead organisms |
OpenBookQA | OpenBookQA-1565 | mass, weight
Title: How to weigh your nephew My nephew is 3 and weighs around 30 pounds I am guessing. However, I would like to weigh him at home. I have kitchen scales, one flat one that goes up 1kg and one that looks like this picture that goes up to 5kg.
What is a safe and practical way I can weigh my nephew at home? I can think of two simple ways.
Lever
The first would be to eschew the scale altogether and build a rudimentary scale with a stick and a pivot, and balance out your nephew's weight with a bunch of water in some buckets, or 2L bottles. Knowing the density of water, you could equate the weight of your nephew to a volume of water. If you are interested in correcting for the weight of the buckets, you could weigh those using your available scales. Or you could use a collection of solid objects and weigh these in turn on your existing scales.
In the same spirit, with access to stick and pivot technology, along with a measuring stick, you could just make the lever arm on the side opposite your nephew a factor of 6 times longer (7 to be safe), and then find some objects around the house to balance out this rudimentary scale. That collection of objects (or water again) could be measured on your existing scales. Knowing this mass, and the ratio of the lever arms on the two sides of the scale, you'll get a weight for your nephew.
The major source of error in both cases is likely to be the uncertainty in the location of the center of mass on both sides. I reckon you could get this down to about an inch or so without too much trouble, which would equate to an error in the mass of around 3% if your lever arm on each side was around 3 feet. Not perfect but decent. With less certainty in the position of the center of mass, or care taken, I would expect an error at the 10s of percent level.
Sock scale
The following is multiple choice question (with options) to answer.
In order to grow as a child I should have | [
"cake",
"cheese",
"candy",
"spinach"
] | D | a living thing requires nutrients to grow |
OpenBookQA | OpenBookQA-1566 | radiation
You see similar things happening here. The metal rod at the top of the lamp acts as a capacitive ground - given the very high voltage, a tiny charge will flow from the tip of the filament to the rod. There is a small amount of gas in the tube which is ionized and gives rise to the light you see. The electrons eventually bombard the metal "anode" and produce Bremsstrahlung - note that without the metal, you were getting a glow and no reading on the Geiger counter. There is a similar demonstration online which is more convincing in its use of conventional materials, but which otherwise shows many of the same phenomena.
It is almost certainly very inefficient. Most of the energy in an X-ray tube is converted to heat as the electrons burrow too deeply into the tungsten target for their radiation to escape- apart from the fact that only the most violent deceleration produces X-rays with high enough energy to penetrate the bulb and be detected.
I noticed that when the "alpha window" was removed, the reading in your video went up. Since there was also a biscuit tin and glass bulb in the way I suspect there was a lot more low energy radiation generated than was detected. Good stuff for skin cancer.
The experiment as shown should not be repeated. Not only were the HV precautions extremely poor, but so were the radiation safety precautions. Please don't try this at home...
The following is multiple choice question (with options) to answer.
A flashlight converts chemical energy into what kind of energy? | [
"light snacks",
"greens",
"food",
"illumination"
] | D | a flashlight converts chemical energy into light energy |
OpenBookQA | OpenBookQA-1567 | geology
Title: Where do riverbed stones come from? Have they always been here since the river was formed? Are some newer than others? Riverbed 'stones' - I assume you mean things like pebbles, boulders, etc. are pieces of rock that have weathered out and been deposited in the river. Some come from rock that is very close to where they are located and some have been transported from very far away. In general (and it is a very broad generalization) the rounder the stone, the longer it has been in the river and the more likely it is to have come from far away. Of course that depends on the hardness of the rock, and other factors, too.
Some rocks are newer than others. Some have been formed quite recently and some are billions of years old.
The following is multiple choice question (with options) to answer.
rocks often contain large amounts of | [
"milk",
"cheese",
"aluminium",
"honey"
] | C | rocks often contain large amounts of metal |
OpenBookQA | OpenBookQA-1568 | everyday-chemistry, thermodynamics, surface-chemistry
Why did the cardboard start to curl up as it began to burn?
Why did it retain its texture if not shape and size? The curling up has a simple reason: the burning was not uniform. Paper contains water (really!), and heating it makes it lose the water.
Now, paper is a bad conductor of heat. When you burn it, inevitably the flame will be mainly on one side(the side that's pointing up). The flame will transfer heat to nearby regions of paper, and evaporate some (or possibly all) of the water. The loss of water leads to a contraction of the cellulose fibers in the paper (I'm not too sure of this, comments appreciated). But, this only happens on one side of the paper. Even though paper is razor-thin, the fact that it still has two "faces" is important here. Now, due to the contraction, the paper curls in that direction (similar to how a bimetallic strip works). That's it.
The reason for retaining texture, is something I'm not too sure about. The burning reaction throws up a lot of soot, but a lot of the products stay right where they are. This results in the charred/burnt paper occupying the previous position of the cellulose. While charred paper isn't a polymer and thus isn't too strong, it can "mimic" the initial structure just by occupying the position of the cellulose. But, unlike cellulose, if we try bending it, it will crumble since there are no long polymer "chains"/intermolecular forces holding it together. It's like the difference between a house of cards and a similar "house", made of a single piece of rubber. The structure is the same, but the former case is only staying together because it had the "luck" to exist in a stable configuration. Disturbing it will destroy it.
The following is multiple choice question (with options) to answer.
I just read about using cardboard in layers for building, but the surfaces should be waxed to keep out water. This premise is used by some _____________ to keep water in: | [
"balloons",
"plastic bottles",
"leaves",
"books"
] | C | waxy leaves are used for storing water by some plants |
OpenBookQA | OpenBookQA-1569 | humidity, air-pollution
Title: Does usual city pollution have effects on relative humidity? I've noticed that in a rural area with low pollution the relative humidity is constantly lower than the humidity in a high polluted city. Is there any correlation between pollution and humidity? By way of reference, "humidity depends on water vaporization and condensation, which, in turn, mainly depends on temperature".
From the information you have supplied in your comments. There are waters in Bucharest and forests in the suburbs, but no waters or forests where the country house is located.
From your information, Bucharest has a number of sources of atmospheric water vapour, the river that flows through it (evaporation of water) and the forests in the suburbs (transpiration of water). Additionally, motor vehicle exhausts will increase the humidity as water vapour is one of the products of the combustion of hydrocarbons.
The warmer the air, the greater its capacity to hold moisture. Cities tend to be warmer than rural areas due to the heat island effect, which is the result of modifying land surfaces and the generation of waste heat.
Humidity in the rural location will arise from evaporation of water in the soil and transpiration from crops or grasses. Such transpiration will produce less water vapour than forests. Additionally, the rural location will have significantly fewer cars producing water vapour in their exhausts. Consequently, the rural location will be less humid than the city.
The reason why Bucharest is more humid that the rural location has more to do with the greater availability and vaporization of water in Bucharest and the temperature of Bucharest than the amount of pollution in Bucharest.
The following is multiple choice question (with options) to answer.
Pollution is extremely difficult to contain in a | [
"refuse facility",
"greenhouse",
"the white house",
"capital building"
] | A | an landfill is a source of pollution |
OpenBookQA | OpenBookQA-1570 | newtonian-mechanics, rotational-dynamics, moment-of-inertia
Agree upon what "the Earth" means, and the answer becomes simple.
The answer probably depends on what you intend to do with the earth. If you want to make it spin just a hair faster, then your definition is probably the more useful. Atmospheric drag and the forces of people upon the dirt as they hit the ground will ensure the people continue to rotate at the same rate as the ground does. Thus, it makes sense to keep them as part of the Earth, just as it made sense to keep the mantle as part of the Earth because it will soon settle and regain its position. In such a situation, your friend is more right.
On the other hand, if you want everyone to jump and then have Superman spin the planet. Spin it fast, fast, fast, faster until it would fling any human that touches it off into space (and thus also fast enough that the Earth will soon disintegrates under its own centrifugal pseduoforces), and I'm going to side with you rather than your friend. In such a situation, the object that Superman must spin has a lower inertia because he doesn't have to spin up the people with it. As such, you are more right.
It's all quite relative, for it's really all language.
The following is multiple choice question (with options) to answer.
The Earth is going to be completing a full rotation. A child notes this, and knows that it means that | [
"a cloud is going to rain",
"the moon is in the sky",
"a day has passed on Jupiter",
"the sun rose, set and rose again"
] | D | a Rotation of the Earth on itself takes one day |
OpenBookQA | OpenBookQA-1571 | In the case where the contestant opens a door other A, not knowing if the prize is behind that door, we do not know in advance that door B would not reveal the prize. The chance that the door B reveals the prize is much lower in the case where the door A is the prize door than in the case where it is not (probability $0$ versus $\frac12$); so the fact that B is not a prize door tells us that the probability the prize is behind door A is greater than we would have estimated previously. In fact, the probability the prize is behind door A increases from $\frac13$ to $\frac12$. The probability that the prize is behind door C also increases from $\frac13$ to $\frac12$.
The following is multiple choice question (with options) to answer.
A person paints a white door a different color, so the door is probably now | [
"still white",
"grey",
"white",
"clear"
] | B | painting an object a color causes that object to be that color |
OpenBookQA | OpenBookQA-1572 | newtonian-mechanics, reference-frames, inertial-frames, relative-motion
This provides the additional force required to move at the same acceleration as the car.
At this instant , your acceleration with respect to the car becomes zero and you no longer move backwards .
You can analyze this situation from the car frame as well.
As the accelerations of the car and the man in the ground frame are different initially, a pseudo force is applied on the man in the backward direction. This pulls the man backwards until his back touches the seat which provides the reaction force (or the normal force) to counter the pseudo force. Thus , the man comes to rest in the car frame
The following is multiple choice question (with options) to answer.
Additional consistent force on a vehicle moving forward will cause that vehicle to | [
"slightly accelerate",
"stop",
"slow down",
"turn"
] | A | a force continually acting on an object in the same direction that the object is moving can cause that object 's speed to increase in a forward motion |
OpenBookQA | OpenBookQA-1573 | thermodynamics, geophysics
Second, any closed system evolves toward thermal equillibrium. In simple terms, if you leave a hot coffee on your table, it will eventually cool down to room temperature. Even though compression increases temperature, this doesn't mean that constant pressure keeps producing more and more heat. When you compress a lot of air into a soccer ball, it will feel hot to the touch. But as it exchanges heat with the environment, it will cool down. This is very useful, of course, because it allows you to expend energy to cool things down, like in your A/C :)
What effect this has on pressure in turn again depends on the properties of the material you're working with. If you have a volume of air in a bottle, as you cool it down, the gas pressure decreases. If you heat it up, the pressure increases. This is the reason why you need to tweak the pressure in your car's tires even if they aren't leaking - you need to adjust for current temperature.
However, with a liquid, this isn't anywhere as simple. While there is a relation between temperature and density, it's nowhere near as big as in an ideal gas. The same goes with pressure and density - if it didn't, you wouldn't be able to walk (imagine that your legs would shorten by half every time you raised one leg - that just wouldn't work).
So, let's put this to use in our ocean example. Undisturbed, water will tend to be "vertically ordered" by density. Usually, this means that warmer water will tend to rise up, while colder water will tend to go down. So the weird thing is actually how relatively warm in the depths. The ocean floor tends to be around the same temperature, regardless of how warm or cold the upper layers are.
There's two main reasons for that, specific to water:
The following is multiple choice question (with options) to answer.
rock from deep down creates what as it becomes less hot | [
"vitamins",
"cracks",
"minerals",
"holes"
] | C | minerals are formed from magma cooling |
OpenBookQA | OpenBookQA-1574 | particle-physics, interactions, subatomic
STM Image of Iron
In your post title, you ask for details at the subatomic level, which I don't think anybody can provide you with.
So I have cheated a bit, and displayed a Scanning Tunnelling Microscope Image at the atomic level, which may be on the scale of the best image we can currently obtain.
What I find interesting about this image, is that is corresponds exactly with what we would expect to see classicaly, all nicely lined up and ordered neatly.
I would doubt that the subatomic level is even possibe to visualise, in other words, an electron is supposed to be an point shaped particle, that takes a 720 degree rotation to get back to its starting point, I have no idea how to visualize that.
The nearest image I can provide you with, where quantum effects start to come into play, is the one below.
From Wave Like Motions
The concept of wave-like motion for electrons has been very difficult to imagine or visualize. What does it mean for a particle to move like a wave? But we can visualize it. Very recently, scanning tunneling microscopy (STM) has been used to take images that clearly reveal this wave-like character. The STM mechanism can be used to literally pick up and place metal atoms in specific arrangements on metal surfaces. For example, iron atoms have been arranged to form a closed circle on a copper surface. An image of the resultant structure then taken using the STM shows not only the ring of iron atoms but also conspicuous waves inside the ring, which result from the motion of electrons moving within the ring and reflecting off of the walls formed by the iron atoms. Two of the original images taken at IBM of these so-called “quantum corrals” are shown below.
This Wikipedia STM article explains the details of the STM, and how it uses the the quantum tunnelling effect to display an image, not of the atoms themselves, but of the electric charge surrounding them.
Any corrections / clarifications to the above statement will be welcomed.
Are they well defined boundaries, or are they "clouds of subatomic particles" that interact or are exchanged at a certain proximity ?
The following is multiple choice question (with options) to answer.
What displays the movement of electrons from the base atoms? | [
"venus",
"mercury",
"plasma star",
"pluto"
] | C | plasma is formed by electrons separating from atoms in stars |
OpenBookQA | OpenBookQA-1575 | Wisconsin Wildflowers Yellow, Adaptability Culture In Organizations, Tree Of Savior Hunting Grounds 2020, 2 Timothy 2:16 Kjv, Aristolochia Florida Native, Best Grass For Goats In The Philippines, Seymour Duncan Sh2 Bridge,
The following is multiple choice question (with options) to answer.
A goat in a lush field of dense vegetation will be bestowed | [
"four lucky hooves",
"poor growth",
"a tin can",
"a shiny coat"
] | D | an animal being born when food is available has a positive impact on that animal 's health |
OpenBookQA | OpenBookQA-1576 | behaviour
Title: What happens to silverfish when we throw them out the window? I'll find a silverfish from time to time in my flat. I don't mind them but usually I catch them and throw them off the balcony (second story) into the bushes and lawn below.
I was wondering, since they seem to live in the water conduits in the house, if they can survive outside or if they die/get killed instantly.
Thx for your help! Silverfish prefer high humidity and warmth. Ctenolepismacalvum (Ritter, 1910) was recently found in Japan at a temperature of 20-30°C and 50-60% RH. As long as there are pieces of bark, wet grass or other organic or human-made structures that retain humidity after each raining event, the likelihood that they will survive long enough to complete their cycle is high.
They could face dessiccation if they are not able to find a damp spot in time, depending on their tolerance to it. However, it was not possible for me to find information about their dessiccation tolerance.
The Zygentoma (silverfish order) have high tolerance to low humidity and most of the species inhabit dry and hot environments (it's just a few that like humidity), which again makes me think that those silverfish propelled out the window will survive.
The following is multiple choice question (with options) to answer.
Salamanders may be unable to survive in a hot, dry location lacking food and water, but if it has food and water in an ideal location | [
"it is extinguished",
"it may flourish",
"it is financed",
"it may crash"
] | B | when a habitat can support living things , living things can live in that habitat |
OpenBookQA | OpenBookQA-1577 | star, orbit, exoplanet, kepler
Title: How do astronomers determine the texture of an exoplanet? So I was wondering how astronomers are able to get the texture/detail of an exoplanet or how they know a planet has water or not. I know how they discover planets by using the light of a star and seeing if it gets faint or by seeing if the star is getting gravitationaly pulled back and forth, to determine the planet size. But I just don't understand how they are able to get the texture of a planet. Thanks for the help! This is known as spectroscopy. Every molecule and atom in the universe emits and absorbs light at specific frequencies. This is a result of the quantization of the energy levels (for electrons) in an atom. Although there are lots of complicating factors, such as redshift, to account for, the patterns are usually so distinctive that the complications can be accounted for, and do not prevent scientists from figuring out chemical compositions (and even, to some extent, how abundant each chemical is).
For example, here are the emission spectra of several common atoms at rest (with respect to the observer):
Absorption spectra, on the other hand, appear as darker regions in the band. Here's an example of an absorption spectra, which identities several elements by knowing that it is distinguished by absorbing light at specific wavelengths that others do not:
For exoplanets with significant atmospheres, we can only expect to see the spectra for its upper atmosphere. All other signals will be muted out by the rest of the atmosphere. We will not be able to tell what the surface looks like, or what it is made of.
The following is multiple choice question (with options) to answer.
A way that scientists determined whether previously known planets truly are still such is based on whether | [
"they complete rotations",
"they have atmosphere",
"they are glowing",
"they have life"
] | A | pluto has not cleared its orbit |
OpenBookQA | OpenBookQA-1578 | homework-and-exercises, radiation, earth, sun
Title: How much radiation does the Earth receive from the Sun's total radiation? I was thinking how to solve this problem. $1\,\mathrm{AU}$ is roughly the distance from the Earth to the Sun, $1.4960 \times 10^{11}\,\mathrm{m}$.
The radius of Earth is approximately $6.4 \times 10^{6}\,\mathrm{m}$, and the radius of the Sun is approximately $6.96 \times 10^{8}\,\mathrm{m}$.
How could we estimate the percent of radiation which the Earth receives, ignoring astrophysical "noise" like dust?
The radiation emitted by the Sun roughly follows the Stefan-Boltzmann law and the radiation emitted is roughly $\propto T^4$, and the surface area of the Earth is roughly $\propto r^2$.
Would you simply take the ratio between the Sun's surface area divided by the Earth's surface area?
All the Sun's power $P$ passes uniformly through a sphere with radius of 1 AU. Calculate the total surface area of this sphere and call it $S$.
The Earth's disc also has a surface area that can be calculated from its radius. Call this surface $S_E=\pi R_E^2$.
The fraction of the Sun's power received by the Earth is thus:
$f=P\frac{S_E}{S}$.
The following is multiple choice question (with options) to answer.
As the Earth crust receives radiation from the sun it | [
"releases CO2",
"loses mass",
"swells",
"thermally increases"
] | D | as temperature during the day increases , the temperature in an environment will increase |
OpenBookQA | OpenBookQA-1579 | visible-light, atmospheric-science, sun
Title: Why is there less UV light on earth in winter? So I have often read that, at least in e.g. northern Europe, in the colder seasons, there is not enough UV (-B) light arriving from the sun, so many people have not enough vitamin-D from that.
At first I thought it was simply due to the sun "shining" for only a much shorter period of time in winter compared to summer and hence less possible exposure (not to mention that most of the skin area is covered then).
But I just had a thought coming to my mind, thinking about that in the mornings and evenings, we mostly see red light here, the higher end of the visible spectrum not getting through.
I am not familiar with the physics behind that phenomenon, but thought that the higher-end of the spectrum like the invisible UV light may not be getting through here for even longer parts of the day towards and away from high noon, and that in winter, the part of the day where UV gets through is maybe very narrow and that's why it's said not to be enough.
Is that correct? And how exactly does this work physically? The reddening of the sun has to do with Rayleigh scattering as the sun passes through more atmosphere. (see picture). This is in a sense, related to less energy but not the primary cause.
The reason we get less solar energy per square meter is that the angle of the sun in the sky affects how spread out the light is. (see updated picture). Ignoring atmospheric effects, it's the sin of the angle times peak energy. 90 degrees or directly overhead, figuring peak solar energy is 1,369 Watts per square meter (that also varies with distance), but the energy from the sun is mostly governed by the sin of the angle.
45 degrees: 1,369 * sin(45) W/m^2 or 71% of overhead or Zenith. 20 degrees above horizon, 1,369 * sin (20), just 34% of peak solar energy. Winter corresponds with the sun being lower in the sky, sunlight is more spread out. There is measurably less energy hitting the same area when the sun is low in the sky.
Passing through more atmosphere amplifies that somewhat, but the angle of the sun is the primary cause.
The following is multiple choice question (with options) to answer.
The earth receives uneven amounts of UV rays due to | [
"height",
"distance",
"it's axis",
"width"
] | C | the Earth being tilted on its axis causes ones side of the Earth to receive less energy from the Sun than the other side |
OpenBookQA | OpenBookQA-1580 | navigation, 3d-navigation
Originally posted by M@t with karma: 2327 on 2017-03-14
This answer was ACCEPTED on the original site
Post score: 17
Original comments
Comment by raultron on 2017-11-21:
Amazing answer. Thank you very much.
Comment by Amina23 on 2020-03-05:
thank you . you're awsome !
Comment by darshb34 on 2021-01-10:
Hi @M@t, Can you please suggest how to integrate 3D slam algorithms like cartographer or hdl_graph_slam with NavStack for navigation purposes? I understand we can setup tf for localization, but how how do we do path planning on 3d maps (we do not get grid maps).
Thank you for the help and appreciate your contribution.
Comment by M@t on 2021-01-12:
@darshb34, that is a question with a very long and complicated answer. Far too long to discuss in the comment section, and possibly too broad even to properly answer in a forum thread. I suggest you create a new question, and try to define what you want to achieve as succinctly as possible.
The following is multiple choice question (with options) to answer.
What is an example of navigation? | [
"reading novels",
"directing rudder",
"cooking",
"sleeping"
] | B | An example of navigation is directing a boat |
OpenBookQA | OpenBookQA-1581 | the-moon, moon-phases
Because the full Moon happens when the Moon and Sun are on opposite sides of the Earth, the Moon is most directly opposite the Sun near the Spring and fall equinox. That makes the Harvest Moon (full moon closest to the fall equinox) and the full Moon closest to the spring equinox, more directly opposite the sun, so they reflect slightly more light to the Earth. This effect basically just makes the Moon a bit rounder than other full moons. If you've ever noticed, mid summer or mid winter, the full moon can appear fatter than it is tall. That's not an illusion, it's due to the 5 degree inclination.
This effect on overall brightness is small, but your eyes might be noticing a rounder moon and seeing it as brighter. It's theoretically possible.
This year's largest moon was in March, so today's full moon is actually smaller than average. Astronomical measurements will always say that the closest full moon is the brightest one because it's larger in the sky and it reflects more total light towards the Earth, but apparent brightness to your eyes might have little to do with it's increasing or decreasing angular diameter and likely has more to do with how clear the night sky is. Our eyes can fool us. It's possible that the smaller moon appears brighter even though it reflects less light because it also scatters less light across the rest of the sky, similar to how a smaller flashlight might appear brighter if you stare into it, compared to a flashlight with a wider opening that gives off more total light.
A clear night is probably the best explanation. I'd pick that over smaller angular diameter or greater roundness. On a clear night, the Full Moon can appear brighter because less light gets scattered around it, making it look bright against a sky that's slightly darker, but you don't notice the sky's variation.
The full moon is also higher in the sky in winter, because it moves mostly opposite the sun. Being higher in the sky mans there's less atmosphere between the Moon and you. Directly overhead should be brighter than at an angle to a person viewing from Earth.
Edit
doing some looking I came across this website. It claims:
The following is multiple choice question (with options) to answer.
The moon is bright in the night sky, especially when full because | [
"Earth shines",
"stars absorb it",
"sunlight brightens it",
"batteries power it"
] | C | the moon reflects sunlight towards the Earth |
OpenBookQA | OpenBookQA-1582 | Hey, thanks for your help guys. For a minute there, I thought that this theoretical person could not safely expect to live to be 82 years old.
9. Jun 16, 2012
### SW VandeCarr
In fact, on a purely probabilistic basis, for any finite time no matter how large, there is a non zero probability that a person would survive that long. So for a sufficiently large population, there would be a theoretic person that would live 100,000 years. This, of course, has no basis in biology.
In terms of the probability of being murdered, the model would not hold for the 100,000 year old person. In terms of the model, probably the best one can do is assume the proportion of causes of death would be constant. The calculation above needs to be corrected for overall survival in terms of death from any cause.
Last edited: Jun 16, 2012
10. Jun 16, 2012
### viraltux
Interesting... but 0.37% is not that small percentage, don't you think? That means, roughly speaking, that a community of around 300 persons can expect that one of them will be murdered.
If you consider that the number of people we know plus acquaintances can easily be around 300 persons that would mean that most 82 year old persons know of someone in their circles who has been murdered. Mmm... that might be an interesting survey.
11. Jun 16, 2012
### SW VandeCarr
As I said in my previous post, this is a misapplication of statistics. You have to consider survival in terms of all cause death. If you just consider the murder rate, then at some point nearly everyone gets murdered.
12. Jun 16, 2012
### moonman239
I know that.
This person will not die until he reaches age 82, if he is not murdered. As mentioned before, this person has a 68% chance of living to be 82.
13. Jun 16, 2012
### D H
Staff Emeritus
The probability of living to 82 per this problem is 99.63%, not 68%. You missed the decimal point on the 0.37%.
14. Jun 16, 2012
### SW VandeCarr
The following is multiple choice question (with options) to answer.
A person who is unable to hunt for nourishment may still survive and even thrive if they | [
"harvest human organs",
"burn crops",
"purchase produce",
"spend time alone"
] | C | humans eat crops |
OpenBookQA | OpenBookQA-1583 | volcanology
Title: Does the size of Earth increase due to volcanism? In a volcanic eruption, magma rushes to the 'outside' of the Earth. Does this mean the size of Earth also increases? If not, how is the volume left after the magma rushed out refilled? This is actually a more complicated question than it seems on the surface (no pun intended). The short answer is that the volume vacated by the magma is eventually refilled by the very tectonic processes that filled it in the first place. Crust is subducted, molten, and then rises to fill magma chambers. The process goes on and on. In some cases the plate that was being subducted eventually disappears (this will happen to the Juan de Fuca plate in a few million years), and the volcanoes associated with become extinct, not dormant but extinct. But generally speaking, volcanism is an ongoing process; the Earth is constantly recycling crustal material
The following is multiple choice question (with options) to answer.
Magma pours out a volcano and what off a cliff | [
"drips",
"suspends",
"freezes",
"sticks"
] | A | matter in the liquid state drips |
OpenBookQA | OpenBookQA-1584 | the-moon, meteoroid
Why: Due to how the velocities all work out, the Moon is always moving forward in its path around Earth / the Sun. It never actually back-tracks during half of its orbit against our orbit around the Sun because the orbit around the Sun is faster than its orbit around Earth. Because of this preferential motion, it is plowing through solar system debris, and so that leading edge plowing through the solar system will accumulate more, larger craters (larger because the impact velocities will be a bit higher).
But: Many different researchers have looked for this effect in the cratering record and have not found any clear signal of it (or, for every study that finds a signal, there's another that doesn't, or, the results are in the noise). So, while modeling is all well and good, if there are not observations to support it, there's always the question of whether the modeling is correct.
Summing Up: Based on models that factor in a lot of the different mechanics going on, they all pretty much say that the leading edge (around 270°E / 90°W) of the Moon should receive a higher impact rate than either the near or far side. However, actual evidence of this effect is hard to come by, so while there's no good reason to say the models are wrong, they cannot yet be confirmed. If the models are correct, the effect is small enough that the difference between expected craters on the near vs far side is too small to be visible in the crater counts, so the far side does have more craters because it is an older surface.
The following is multiple choice question (with options) to answer.
The moon is always illustrated in movies and drawings as being very rough and bumpy due to craters, but there are many areas that are | [
"smooth",
"Earth",
"rainbow",
"edible"
] | A | the moon 's surface contains flat areas |
OpenBookQA | OpenBookQA-1585 | species-identification, marine-biology
Title: help identify this fish
I came across this washed up fish in Panama City, Florida in November 2015. I'm guessing it's a puffer fish but I can't find anything like it online.
Thanks. This is a kind of trunkfish. (They have different names, this could be a smooth or spotted trunkfish.). It's really a lovely and comical little fish when observed alive in coral reefs. It has the ability to change its coloration depending on whether it's excited or calm, or to minimize its contrast to the background. It is related to puffer fish.
It has a boxy, triangular body shape, and propels itself with relatively tiny, delicate fins. Like pufferfish, they are toxin producers.
In death, the body shape and coloration are different, of course. Never saw a dead one before; sad. The juveniles are adorable:
Members of this family occur in a variety of different colors, and are notable for the hexagonal or "honeycomb" patterns on their skin. - Wikipedia
The following is multiple choice question (with options) to answer.
Some fish are | [
"cannibals",
"Dry",
"Land animals",
"Magic"
] | A | carnivores only eat animals |
OpenBookQA | OpenBookQA-1586 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
Camel humps are a good example of | [
"Iraqi roadside prime cuisine",
"seats for desert dwellers",
"a popular brand of shoe",
"changing to meet the environment"
] | D | An example of an adaptation is camel humps |
OpenBookQA | OpenBookQA-1587 | forces, pressure, fluid-statics, air, gas
I hop this description is clear enough, if not, feel free to ask for an explanation.
EDIT: Alright, I think I have understood it now. So the vacuum fills up because gas molecules move "randomly" around all the time and bump into each other. If there is a vacuum somewhere, they can freely move into there because there is nothing to bump against, so a lot of them end up in there, causing the pressure to equalize, because when it is, the molecules continue bumping around but do not "favour" a certain direction because there is less resistance there anymore.
Wind exists, because of course when many molecules have moved a certain direction, there are less of them where they used to be, which again is a lower-pressure area so it also fills up. This happens untill everything is mostly calm again.
Also, does this mean that pressure is the sum of the forces acting on the walls by the molecules randomly hitting the walls?
Is this correct? 'Pressure' of a gas is generated because of the collisions between gas molecules-gas molecules or gas molecules-wall of the container. Unless they collide, gas molucules move in straight lines with uniform velocity, which requires no external force (The impulsive forces act at the collisions are internal forces to the system).
If you put some gas molecules into a bottle, they spread throughout the bottle because there are no barriers inside the bottle. But they cannot go through the wall of the bottle. If you open the lid of the bottle, some of them come out to equalize the pressure inside and outside, because they like to minimize the number of collisions between them [ peace-loving :) ]. That is simply called they move due to pressure difference. But the real reason is you removed the barrier which prevented them from moving freely.
Imagine this way, you are running along a straight line and you see a door closed, so you turn back and again run. Next time you come and the door is opened so you freely move through the opened door. Did any force act on you? No.
In your example, the air is moving to the vacuum simply abolishing the pressure difference (This is explained in more details above) with uniform velocity. Therefore no force acts on the air. Thus no counter-force!
The following is multiple choice question (with options) to answer.
An object that contains gas often goes | [
"in circles",
"forward",
"down",
"up"
] | D | a balloon contains gas |
OpenBookQA | OpenBookQA-1588 | evolution, biochemistry, physiology, speculative, bioinorganic-chemistry
While iron skeletons might seem to be an advantage, they are electrochemically unstable - oxygen and water will tend to oxidize (rust) them quickly and the organism would have to spend a lot of energy keeping it in working form. Electrical conductivity sounds useful, but the nervous system favors exquisite levels of control over bulk current flow, even in cases like electric eels, whose current is produced by gradients from acetylcholine.
What's more, biological materials actually perform as well as or better than metal when they need to. Spider silk has a greater tensile strength than steel (along the direction of the thread). Mollusk shells are models for tank armor - they are remarkably resistant to puncture and breakage. Bone is durable for most purposes and flexible in addition.
The time it would take for metallized structures to evolve biologically are likely too long. By the time the metalized version of an organ or skeleton got started, the bones, shells and fibers we know probably have a big lead and selective advantage.
The following is multiple choice question (with options) to answer.
A hermit crab may find good protection from elements in | [
"a mountain lion",
"a sky color",
"a stone configuration",
"a mouse carcass"
] | C | rocks are a source of shelter for small animals in an environment |
OpenBookQA | OpenBookQA-1589 | concentration
Title: Shouldn't mineral NPK fertilizer ingredients add up to 100%? I use a mineral based fertilizer in powder form which - according to the label - should not contain any fiber and is fully soluble in water (I dissolved 2 times the recommended dosage and found no solids remaining in the solution):
The NPK + Mg + trace elements add up to about 60%.
What constitutes the rest? There is a specific convention how the nitrogen, potassium and phosphate concentration is given, and it might be surprising because it mentions substances that are not in the fertilizer, namely nitrogen atoms, $\ce{P2O5}$, $\ce{K2O}$ and $\ce{MgO}$. You have to imagine that all of the nitrogen, phosphorous, potassium and magnesium in your sample reacts to form these species, and then you express the masses of those fictitious products as percentage of the original mass.
$$\text{fertilizer}\ce{-> x N + y P2O5 + z K2O + q MgO}$$
For an example, look at this answer: https://chemistry.stackexchange.com/a/64282 which links to this reference https://en.m.wikipedia.org/wiki/Labeling_of_fertilizer
The following is multiple choice question (with options) to answer.
Soil contains | [
"the highest portion of the ozone layer",
"the rotten idea of a decaying democracy",
"waves of salt-water moving back and forth",
"chemical substances found in every living thing"
] | D | if some nutrients are in the soil then those nutrients are in the food chain |
OpenBookQA | OpenBookQA-1590 | zoology, species-identification, ornithology, behaviour
Title: What is this crow eating, and is it a common part of the corvid diet? Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:
Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.
What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird? Crows are omnivorous, and will eat almost anything they find or can kill.
In this case the prey looks like a Yellow-Shafted Flicker.
The following is multiple choice question (with options) to answer.
Birds sometimes eat what? | [
"grass",
"underground crawlers",
"insecticide",
"trees"
] | B | birds sometimes eat insects |
OpenBookQA | OpenBookQA-1591 | human-biology, food, neurotransmitter, receptor, taste
Title: Why do Hot/Cold drinks taste sweeter once returning to room temperature? Now, I know this is a very bizarre question, and I tried to find a correct exchange for this, but it might relate to biology/science as it being our taste buds and everything.
I am so sorry if there is a better exchange for this, but (I hate using this excuse) I'm new to StackExchange, so please be gentle and point me in the right direction.
Now, to meat and bones (Unintended pun; meat...bones...biology hehe), over the last few days I have noticed that after my drink returning to room temperature, it is so much sweeter than it originally tasted.
Drinks
Hot Tea - I normally only add 1-2 teaspoons of sugar into my tea and it tastes just right, though after taking a sip when it had returned to room temperature, it tastes about 3 or 4 times sweeter than when it was hot/warm. (Milk)
Iced Tea (Bubble Tea) - Just today I had a bubble tea with the smallest amount of sugar possible, it was still too sweet but I stuck with it, and again when it reached room temperature, it was almost unbearably sweet. (No milk)
Slurpee - Again, after returning to room temperature, it is extremely sweet, with it being much lighter with respect to sweetness.
Hot Coffee - Come to think of it, I have also had the same experience with sugared coffee.
Coke - Also, when coke (or any other soft drink) is flat and room temperature, it also produces the same super sweet taste.
The following is multiple choice question (with options) to answer.
What causes food to taste sweet? | [
"crystal sucrose",
"heat",
"salt",
"pepper"
] | A | sugar causes food to taste sweet |
OpenBookQA | OpenBookQA-1592 | species-identification
Title: What bird / animal has this call? USA MA NE
I have a bird / animal coming to the trees in the backyard making this call (see link to audio file), which does not really sound like a bird - it's fairly low frequency. I have not seen it. Sometimes it sits in a young tree, where you can almost see through to the trunk. But I cannot make it out, so it's not very big (like a turkey). It comes at late afternoon and stays around until ~11PM. It switches trees fairly quickly, so I assume it can fly. The call is always the same. Sometimes another one of its kind answers.
Bird_animal_call_mp3
You don't need dropbox. Ignore "suspicious link". Close login popup. Click download arrow. Direct download.
I added a Soundcloud link:
Bird_animal_call_mp3 It is a grey tree frog's mating call. See youtube link:
Grey tree frog mating call
Source for finding the answer: Audubon Society
The following is multiple choice question (with options) to answer.
Where could you expect to see a quail sleeping? | [
"box",
"field",
"ocean",
"tree"
] | B | female birds sit in nests |
OpenBookQA | OpenBookQA-1593 | # Combination Question
#### Swazination
##### New member
How many combinations can I make if I have 4 letters A,G,C,T and I want to make groups of 5. Yes, you can repeat the letters.
#### Denis
##### Senior Member
From AAAAA to TGCAA
or (if replaced by digits 1 to 4):
from 1111 to 43211
Yes?
#### ksdhart2
##### Full Member
Combinations/Probability problems of this sort almost always come down to pattern recognition. In fact, learning how to find a pattern and extrapolate what comes next will help you greatly in nearly every aspect of mathematics. So let's try using those skills and see what we can come up with for this problem. Let's start with a much simpler version and build up as we go along. Suppose we had two letters (A and G) and one slot. How many combinations would there be? Well, obviously the answer is two. That's not very interesting nor does it seem helpful just yet, but we'll keep in mind all the same.
Now suppose we had two letters and two slots. How many combinations would there be then? Thinking about it, we can force the first slot to be A, then there's two possibilities for the second slot. Similarly, if we force the first slot to be G, we have two additional combinations. So we have two possibilities for the first slot, and for each of those two possibilities, we have two possibilities for the second slot. That gives us a total of 2 * 2 = 4 = 22 combinations.
Now suppose we had two letters and three slots. How many combinations would there be then? I see that we can arbitrarily fix the first two slots and then let the third one vary. Since we already know that there's four possible ways to arrange the first two slots, and for each of those four possibilities, there's two choices for the third slot, that gives us a total of 4 * 2 = 8 = 23 combinations. Are you seeing a pattern? How many combinations would there be with four slots? Five slots? n slots?
The following is multiple choice question (with options) to answer.
Which item can be used more than once? | [
"toilet paper",
"cloth pad",
"tampon",
"drugstore pad"
] | B | something reusable can be used more than once |
OpenBookQA | OpenBookQA-1594 | orbital-motion, space, rotation
Title: How many times does the ISS celebrate New Year each year? My question is, how many times each year do the crew of the ISS have an opportunity to celebrate New Year? Does it vary each year or will it be a fixed number?
I tried to work this out for myself and my brain just went bang, so if anyone out there with more of a maths head could answer this for my I'd be very grateful.
P.S. Sorry if this question is on the wrong website. The ISS travels from West to East (with an inclined orbit). That means it crosses the international date line 15 times per 24 hour period, with time "going backwards" as they do so. This also means they must cross "midnight of the New Year" that many times. Although - since the orbit is 15.5 revolutions per 24 hours it's possible that they sneak in a 16th glass of champagne.
Although as said above, they only celebrate it at UTC.
If you want to know where the ISS is at any moment in time, you can go to http://www.isstracker.com/ . You could watch that site for 24 hours around New Year's eve and get the definitive answer.
The following is multiple choice question (with options) to answer.
What orbits the earth 13 times per year? | [
"night illuminator",
"clouds",
"oceans",
"moon pictures"
] | A | the moon orbiting the Earth approximately occurs 13 times per year |
OpenBookQA | OpenBookQA-1595 | Buffon's needles : lab report: purpose the purpose of this project is to explore a monte carlo method of estimating the value of pi (p), which was first discovered by count buffon in 1733 buffon's needle: an analysis and simulation. Buffon's needle, mste, university of illinois mste office for mathematics, science, and the remarkable result is that the probability is directly related to the value of pi analysis and original java applet by george reese (1996) modified by pavel safronov. Unbiased systematic sampling plans for the line intercept method buffon needle problem using this probability, he derived the use the correlation in the analysis of the data this technique is beyond. Buffon's needle an analysis and simulation monte carlo estimation of pi program in xds modula-2 monte carlo method: determination of the value of pi program in fortran anirban mudi, department of chemistry. Find pi pi day live find pi event format technical support on the ancient egyptian value for pi, from the number warrior blog do this one because we are keen to gather as much data as possible to create the biggest buffon needle experiment in history method. The accuracy of buffon's needle: a rule of thumb used by can be derived from buffon's analysis which relates the here we detail experiments to test this prediction and also present experiments to quantify the accuracy of the buffon's needle algorithm methods collection and.
Fostering understanding of monte carlo simulations since such knowledge provides them with the understanding necessary to justify estimation with the monte carlo method 2 estimating figure 6 buffon needle applet. Buffon's needle was the earliest problem in geometric probability to be solved a statistical analysis of intermediate results he reported for fewer tosses leads to a very low probability of achieving such close agreement to the expected value all through the pi and buffon's needle. The buffon's needle problem: first monte carlo simulation m ragheb 9/13/2013 23 laplace's estimation of the value of pi ( ) procedure for estimating the value of pi, using the buffon's needle problem. The method is called buffon's needle because it was discovered by the french naturalist your task is to write a program that calculates an approximate value of pi by simulating the dropping (see for a version.
The following is multiple choice question (with options) to answer.
Louis Pasteur found a way to | [
"make food tasty",
"make food healthier",
"make food wet",
"make food green"
] | B | Louis Pasteur invented pasteurization |
OpenBookQA | OpenBookQA-1596 | (495, 1), (496, 1), (496, 3), (494, 3), (494, 1), (495, 1), (495, 2), (493, 2), (493, 1), (494, 1), (494, 3), (493, 3), (493, 2)$$ Here is an illustration of this cycle:
The following is multiple choice question (with options) to answer.
365 solar cycles is equivalent to | [
"4 full moon cycles",
"2 years in deep space",
"a trip to the moon and back",
"one trip around the sun"
] | D | one year is equal to 365 days |
OpenBookQA | OpenBookQA-1597 | electric-circuits, electric-current, electrical-resistance, batteries, short-circuits
Title: The importance and the role of a switch in an electrical circuit There is this simple test:
Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed:
a] The brightness of $A$ and $B$ remains the same, while $C$ goes out.
b] The brightness of $A$ and $B$ remains the same, while that of $C$ is halved.
c] The brightness of $A$ and $B$ decreases while $C$ goes off.
d] The brightness of $A$ and $B$ increases while $C$ goes off.
For my opinion the answer to this question is D because the switch (which has a resistance of $0\, \Omega$ has a node connected before the third bulb C) that "interrupts" the circuit. But, going into detail, according to Kirchhoff's first law the current should also go on the third bulb as in the first red node it divides into two currents $I_1$ and $I_2$. The current $I_1$ goes for example in the key $S$ and $I_2$ in the third bulb. The key and the third bulb have the same potential difference. I believe that the current $I_2$ passes through the third bulb but the current passing through it is so small that it does not turn on.
I made a point. When an individual is operated on at the heart and puts a by-pass (a bridge), blood will flow on the tube that detects the by-pass and the occluded artery (the third bulb) where blood will flow slowly, over time it will atrophy.
If the circuit were like the one drawn in the picture I would answer the b).
My question is: I have not very clear the rule of a switch in a eletric-circuit.
In fact, I find it difficult to give an answer to the following image.
The following is multiple choice question (with options) to answer.
A boy leaves a circuit in the wall open, then when he goes to turn on the lights | [
"it fails",
"it succeeds",
"it shines",
"it works"
] | A | electricity can not flow through an open circuit |
OpenBookQA | OpenBookQA-1598 | photons, material-science, absorption, optical-materials, glass
There are further complications to all of this as well. Will the light undergo scattering processes that may allow the light to move through a material, while changing directions and potentially even turning back on itself without being absorbed? Once light has been absorbed, does it simply dissipate the excess energy through the material as heat, fluoresce it back as visible light (and in what direction?), or even do more "forbidden" transitions such as phosphorescence? The answer to all of these questions is "yes, but in varying degrees specific to the material." It even depends on the physical size and amount of material that you have present! So your worries about the rate at which light is able to pass through different materials really just becomes a question of how likely it is for the light to become "sidetracked" as it passes through the material. The net result is an apparent change in how fast the light passes through.
So finally, we can connect all of these nuanced ideas which could each fill a book of discussion on their own (and have) to the macroscopic perspective. All of these properties, for a material like a bulky glass window pane, can be summarized with three simple parameters such as the coefficients of absorption, transmittance, and reflectance of the material. Obviously, for light moving through normal glass, there is an overwhelming victory of the transmittance effects over the absorption and reflectance effects. Of course, you have also clearly experienced that standing at an alternate angle changes the propensity of reflectance of different kinds of light, mostly because you have changed the relative orientation of the light with respect to the overarching structure of the glass itself. This is explained much more deeply within the field of chemical crystallography.
The following is multiple choice question (with options) to answer.
glass crystals will cause light to | [
"go out",
"dim",
"deflect",
"brighten"
] | C | objects made of glass cause refraction of light |
OpenBookQA | OpenBookQA-1599 | energy-efficiency, thermal-insulation
greater if the window is bigger
less as temperature difference get smaller
Radiative heat transfer
The main factor that is of consideration here is the solar radiation. There are three types of radiation:
Direct radiation: the direct rays of the sun. (this is zero on a cloudy day).
Diffuse radiation: this is always present and its an effect of the presence of atmosphere. In higher latitudes it tends to increase because the sun rays need to "pass through" more atmosphere.
reflected (you can neglect this)
If you can get the rays of the sun (direct radiation) into the house, this will always be a significant plus in the heat balance of the house.
Final thoughts
This problem is very instance specific depending on:
the location of the house
orientation of windows
type of blinds, etc.
Therefore, it is impossible to draw a generic conclusion. As such, only trends can be realistically observed.
At a temperature difference of 30$[^oC]$ it makes sense to close the blinds on a cloudy day. However, if you get closer to 15$[^oC]$ then the savings are diminished.
If the windows are positioned in the right angle and light shines into the room, then expect the added solar radiation will improve the heat balance in favour of open blinds.
The following is multiple choice question (with options) to answer.
Because building a house requires a lot of daylight, it's best to do it in | [
"January",
"December",
"July",
"a cave"
] | C | the amount of daylight is greatest in the summer |
OpenBookQA | OpenBookQA-1600 | quantum-mechanics, electromagnetism
Title: Can you magnetize iron with a hammer? We know that a piece of ferromagnet, such as iron, can be magnetized by putting in a strong magnetic field to get domains parallel to the field grow.
I also remember from pop. culture and MacGyver old tv series that you can magnetize a piece of iron by hitting it hard, with a hammer say, along the same direction.
1-Is this way of magnetizing iron scientific? or is it pseudoscience?
and if it is scientific then:
2-what is the physical principle that will allow iron to get magnetized by hitting? and
3-how about nonferromagnetic materials? Seems that it can be done, and here are instructions
Copying from the link
Strike an iron nail squarely and sharply several times with a hammer while keeping the nail positioned in a north-south orientation. The impact of the hammer with the iron nail causes the magnetic domains within the nail to break loose from their current orientation. The Earth's magnetic field will then reposition the domains into a new orientation parallel with the Earth's magnetic field.
It is evident that this can be done only with materials that have small domains with magnetization, which are randomly oriented, so the material has to be ferromagnetic.
The following is multiple choice question (with options) to answer.
If an electromagnet is active then a nail touching it will become what? | [
"frozen",
"reactively charged",
"cold",
"magnetic personality"
] | B | if battery in an electromagnet is active then the nail in the electromagnet will become magnetic |
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