source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-2401 | forces, free-fall, scaling
Assuming the last assumption is correct, how are assumptions 2 and 3 related? Is there anything I missed?
Overall, which person can withstand falls from greater heights: a lighter one, or a heavier one? It is difficult to determine which will fare better.
Small mammals can survive a fall from arbitrary distances. Here's one article I found talking about cats. A chief contributor to small mammals' survival is that they have a lower terminal velocity due to the way wind resistance scales. Wind resistance scales with the area of the animal, while weight scales with the volume, so large animals fall faster because they have a higher volume-surface area ration. On a long fall (hundreds of times the animal's body length), body size influences impact velocity
Even without this effect, small animals may have an advantage. In humans, we can study the statistics of plane crash survivors. According to Wikipedia "Since 1970, two-thirds of lone survivors of airline crashes have been children or flight crew." Children make up a small percentage of passengers, so it follows they have a better chance of surviving. It's no great leap to attribute this to their body size. However, a BBC news story has an expert saying there is no physiological advantage to being a child when it comes to surviving a plane crash.
I have occasionally seen this sort of question addressed with dimensional analysis, but the difficulty is that it's difficult to pin down what you want to try to scale. The peak force or pressure, the energy dissipated per unit mass, the peak power dissipation per unit mass?
Here's an example argument:
If we assume the two people are impacting at the same speed, they need to dissipate the same amount of energy per unit mass. Assume that people can dissipate a certain amount of energy per unit mass in a given time without harm. Then whoever can make the impact last for a longer time will fare better. A taller person can bend their legs through a longer distance, and therefore can make the impact take a longer time, and therefore can fare better.
However, the assumptions in this argument would need to be verified before we can take it very seriously.
Here's another argument:
The following is multiple choice question (with options) to answer.
A bear that has great strength, when compared to a bear with little strength, will likely be | [
"sickly",
"objectively fit",
"malnourished",
"in poor health"
] | B | being stronger usually has a positive impact on an organism 's health |
OpenBookQA | OpenBookQA-2402 | geophysics, sedimentology, glaciology, topography, isostasy
Are there any other reasons? What are the relative proportions in magnitude of these factors? Forming of coastline
During the last ice age, the North Sea was dry. When the ice melted sea levels slowly started to rise again and due to tides and currents
a barrier of dunes was formed along what approximately is today's coast line. This created an area of land that fell dry during ebb-tide and flooded during high tide (this can still be seen in the 'Waddenzee' in the North of the Netherlands where you can walk to some of the islands during low tide). The big rivers that flow through the Netherlands brought in more sand, slowly keeping larger parts of the land dry.
Isostatic rebound
During the ice age, the surface of Scandinavia was pushed down. After the ice melted it started to rise again and pushed the Western and Northern part of Netherlands down. Strangely enough the Southern and Eastern parts of the Netherlands are rising, so it seems the Netherlands is tilting.
I'm not sure how large the isostatic effect has been, but we know that the North of the Netherlands is still going down with about 2cm per century (source in Dutch).
Human influence
I know you've asked for non-anthropogenic causes, but I'm going to include this anyway because it seems human influence has had a much bigger effect on elevation than the isostatic rebound.
In the 11th century the Dutch started to actively shape the land by building dikes and later also by using wind mills to pump out water. The Flevopolder is an example of a large part of land that has been created by the Dutch in the 1950s and 60s. When groundwater levels became lower the moors settled and started oxidizing. Researchers think that the settling and oxidation of moors today is responsible for up to 15mm decline per year (source in Dutch).
Additionally in the 16th and 17th century a lot of peat was removed from the moors and used as fuel. Peat removal created new lakes, but some of those lakes were pumped dry later and were used as farmland. Also, the weight of dikes and houses on moors still cause subsidence today in areas in the West.
In the Northeastern part of the Netherlands gas extraction has also caused local elevation drops of up to 30cm (source in Dutch) in the last 40 years.
Other sources (all in Dutch):
The following is multiple choice question (with options) to answer.
2000 years ago, this method would likely have brought sand from the coast to the desert | [
"the pyramids often eroded, making their own sand",
"constant breezes over time",
"human automobiles transfer materials",
"the space shuttle moved sand great distances"
] | B | wind carries sand from one place to another place |
OpenBookQA | OpenBookQA-2403 | meteorology, wind
Is this the correct definition? I'm a bit confused, since this contradicts the company support guys (which are specialist for this thing). They insist, there is not time-averaging-period attached to the definition of "Wind gust" which is, in my understanding, not sensible. There must be some time information attached to any definition of "wind gust" as far as I understand? But then again I'm not a meteorologist and might miss something basic.
Obliged for any help to clarify this respectively lets me understand this better. The WMO definition of wind gust for observing stations is,
The following is multiple choice question (with options) to answer.
A person wants to know how fast winds will be going this week. They buy a device made of metal and | [
"place it outside next to the chimney",
"place it in the basement of their house",
"place it on the ground outdoors",
"leave it in the car overnight"
] | A | an anemometer is used to measure wind speed |
OpenBookQA | OpenBookQA-2404 | 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.
Which would be the best conditions to drive in? | [
"heavy snowfall + cold weather",
"blizzard conditions + hurricanes",
"blizzard conditions + lightning",
"blizzard conditions + earthquakes"
] | A | bad weather decreases visibility while driving |
OpenBookQA | OpenBookQA-2405 | geography, geomorphology, satellites, satellite-oddities
Title: What produces these distinct shapes in the Rub' al Khali seen from space? update: Searching "Rub' al Khali Empty Quarter" found "Q2: What are sabkhas?" in
https://www.geocaching.com/geocache/GC6BYQ0_rub-al-khali-the-empty-quarter which seems to be related.
From the NASA image gallery; and also Catalog Page for PIA11084 where the caption says:
Original Caption Released with Image: The Rub' al Khali is one of the largest sand deserts in the world, encompassing most of the southern third of the Arabian Peninsula. It includes parts of Oman, United Arab Emirates, and Yemen. The desert covers 650,000 square kilometers, more than the area of France. Largely unexplored until recently, the desert is 1000 km long and 500 km wide. The first documented journeys made by Westerners were those of Bertram Thomas in 1931 and St. John Philby in 1932. With daytime temperatures reaching 55 degrees Celsius, and dunes taller than 330 meters, the desert may be one of the most forbidding places on Earth.
The image was acquired December 2, 2005, covers an area of 54.8 x 61.9 km, and is located near 20.7 degrees north latitude, 53.6 degrees east longitude.
The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.
Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
Image Addition Date: 2008-08-08 The pattern shown in this image has an amazing amount of approximate repetition of shapes; long straight segments with a periodicity of about 2 kilometers, "stair steps" northward and sharp, pointy extensions southward. Is there any understanding how such a distinct pattern could be formed?
below: "Rub' al Khali (Arabian Empty Quarter) sand dunes imaged by Terra (EOS AM-1)" cropped and full sized (reduced resolution) images from here.
The following is multiple choice question (with options) to answer.
Where would a sand dune be out of the ordinary? | [
"the Sahara desert",
"the Iraqi Desert",
"the Gobi Desert",
"Kansas"
] | D | sand dunes are made of sand |
OpenBookQA | OpenBookQA-2406 | plant-physiology
Title: Would a plant survive if it was watered using hard-water? Hard water is water with high mineral/salt content. I'm told that a potted plant watered with a salt solution dries out sooner or later. Is this true?
If so, would a plant survive if watered using hard-water? It would depend on the content of the hard-water. If the water contained heavier metals like lead or radioactive elements like tritium (Hydrogen-3), the plant would most likely die. Most land plants cannot survive when watered with massive amounts of salt water as the salt would absorb the water from the leaves.
The following is multiple choice question (with options) to answer.
Usually, plants naturally decrease their intake of water in roots and branches to withstand | [
"springtime",
"rising temperatures",
"cool breezes",
"very cold temperatures"
] | D | usually plants die or become dormant during the winter |
OpenBookQA | OpenBookQA-2407 | newtonian-mechanics, classical-mechanics, differential-equations, vibrations
There are 2 ways round this difficulty. The 1st is to simulate the motion numerically, in small time increments. The 2nd is to approximate, for example by making the assumption that the motion of the ball is not affected by the motion of the platform - then $F(t)$ is a periodic impulse of constant amplitude (see for example section 7.2 of these notes) - or that the motion of the platform is not affected by the motion of the ball.
The following is multiple choice question (with options) to answer.
The motion of a ball's motion when touching a concrete sidewalk will be countered due to | [
"abrasion",
"lipids",
"dairy",
"thinking"
] | A | friction acts to counter the motion of two objects when their surfaces are touching |
OpenBookQA | OpenBookQA-2408 | 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.
A person wanting to gather dirt for their garden would harvest it from the | [
"top layer of earth",
"core of the earth",
"bottom layer of earth",
"middle layer of earth"
] | A | the top layer of soil contains the most nutrients |
OpenBookQA | OpenBookQA-2409 | atomic-physics, history, brownian-motion
Step 2) Because we know pollen is a particle -> sugar must be a particle also
So then why not just measure the osmotic pressure of pollen and then the proof is done? Well I think the problem is that the osmotic pressure is going to be so tiny its undetectable. So back to step 1, he had to find a roundabout way to calculate osmotic pressure, thus kicking off the whole diffusion, random walk statistical analysis which ultimately culminates in Avogadro's constant. Since the same constant governs pollen and sugar, step 2 follows.
Btw I know this is not mathematical proof. Step 2 is not a hard corollary of step 1. To reiterate my key point, Einstein's analysis was not to say anything about the molecular nature of the liquid. It was merely showing that random motion of large particles and molecules from a solute are governed by the same equations.
The following is multiple choice question (with options) to answer.
A bud will want pollen to be extracted and then spread, so it will require | [
"assistance from vice principals",
"delivery to the door",
"assistance from flying creatures",
"help from new neighbors"
] | C | A bee is a pollinating animal |
OpenBookQA | OpenBookQA-2410 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
Why would soil be more loosely packed than it was the previous day? | [
"the local eagle population",
"the native American population",
"the neighborhood human population",
"the native worm population"
] | D | tunnels in soil loosen that soil |
OpenBookQA | OpenBookQA-2411 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
A cow will gain energy from eating | [
"dandelions",
"eggs",
"frogs",
"birds"
] | A | cows only eat plants |
OpenBookQA | OpenBookQA-2412 | thermodynamics, planets, atmospheric-science, rocket-science, fusion
Adding ever more CO2 to an atmosphere has a logarithmic effect. Adding more CO2 to Mars' already saturated atmosphere won't have much of an effect.
Mars low gravitational acceleration means the dry adiabatic lapse rate on Mars is less than half that on Earth. Greenhouse gases move an atmosphere away from an isothermal atmosphere toward an adiabatic atmosphere. Mars thin atmosphere and low lapse rate alone explain most of why the greenhouse effect on Mars is significantly less than that on Earth.
There are two bands in the thermal infrared where CO2 is a very good absorber/emitter of radiation. One peaks at Earth equatorial temperatures (Mars doesn't get anywhere near that hot), the other peaks at Earth polar temperatures (that's Mars). That lower peak means that, except for polar regions, Earth's middle troposphere to upper stratosphere are extremely opaque to infrared radiation. Mars atmosphere on the other hand gets increasingly more transparent in the infrared with increased altitude.
Nukes could help warm Mars. Mars' energy budget varies considerably with Mars' weather. Mars occasionally suffers planet-wide dust storms. While those dust storms increase Mars' albedo, they change the energy flux to and from the surface by more than enough to compensate for this lost incoming energy. If the goal is to heat Mars up, it would make a lot more sense to nuke Mars' equatorial regions instead of its poles. We'd have to do this on a regular basis to have any effect. Whether or not this is a good idea is a different question.
The following is multiple choice question (with options) to answer.
Which would increase atmospheric carbon by the lowest degree? | [
"trees",
"humans",
"cattle",
"dogs"
] | A | as the population of plants decreases , carbon in the atmosphere will increase |
OpenBookQA | OpenBookQA-2413 | zoology, ethology, behaviour, psychology, death
Strange thought
Organisms that have not evolved the ability to make "conscious choices" cannot decide to end their life. You will be hard-pressed to find any scientific data on this question. Psychology in humans is already a difficult study, at times failing to demonstrate results with real scientific rigor. When studying animal psychology, you face another substantial barrier - language. Although some primates have been taught to communicate with sign language, the best of them are still far from the level of proficiency of a human. We can measure brain activity and observe behavior, which can lead us to strong suspicions about what is going on in an animal's mind, but very little can actually be proven.
Mostly, all we can do is speculate about such questions. You will find some veterinarians out there who treat pets for mental conditions, but you will find at least as many people calling them quacks as those who believe in the validity of their work. And certainly, they can't prove to you that a treatment has helped an animal. It's subjective.
If we see an animal do something which in a human might reliably be interpreted as a sign of depression, it's possible that this interpretation is appropriate for the animal as well. It's also possible that there is some totally foreign unrelated explanation. The problem we find when trying to scientifically discuss matters which cannot be proven scientifically is that scientists must be careful to state what they know and nothing more. So they might say "We cannot prove that the porpoise is depressed", or "Science cannot prove the existence of a God." This is often misinterpreted as evidence against the finding - that the porpoise is not depressed; that there is no God. This is a fallacy. Rather, we should recognize that we have different ways of exploring questions like these.
The following is multiple choice question (with options) to answer.
Animals make decisions based on | [
"their feet",
"inside their heads",
"their spines",
"their homes"
] | B | an animal 's brain controls that animal |
OpenBookQA | OpenBookQA-2414 | Question
Find a relationship between $$x$$ and $$y$$ so that the triangle whose vertices are given by $$(x,y),(1,1)$$ and $$(5,1)$$ is a right triangle with the hypotenuse defined by the points $$(1,1)$$ and $$(5,1)$$.
A
(x+3)2(y1)2=22
B
(x3)2+(y1)2=22
C
x2+y2=22
D
(x3)2(y2)2=32
Solution
The following is multiple choice question (with options) to answer.
Which is the correct relationship? | [
"the moon orbits the sun which orbits the Earth",
"the moon orbits the Earth which orbits the sun",
"Earth orbits the moon which orbits the Earth",
"Earth orbits the sun which orbits the moon"
] | B | the moon orbits the Earth |
OpenBookQA | OpenBookQA-2415 | electromagnetism, electromagnetic-induction
To see that this makes sense, consider the definition of emf: It is the work done on an electric charge over some path. Imagine a unit charge inside an electric field $\vec E$. To move this charge an infinitesimal distance $d\vec s$, we need energy $\vec E . d\vec s$. To get the energy over the whole loop, we simply integrate that term.
It also makes sense dimensionally: The unit of the electric field (in SI) is kg⋅m⋅s−3⋅A−1, and the unit of the volt is kg·m2·s−3·A−1, which is just the former multiplied by distance.
The following is multiple choice question (with options) to answer.
To move electrical energy around a field, a person would use | [
"tin pipes",
"glass tubing",
"plastic wires",
"wood barrels"
] | A | metal is an electrical energy conductor |
OpenBookQA | OpenBookQA-2416 | climate-change, climate
In this case, as it is an area that it is almost constantly cloudy with high humidity, temperature is varying just a little bit, and except the first day of the period, it seems that there is no relationship. In fact, on the second day there was a storm (I am living now at Singapore) and it is reflected in a quick change in temperature (both) and solar radiation.
Conclusion: It is not as simple as it seems.
Hope it helps!
The following is multiple choice question (with options) to answer.
A day that is cloudy will | [
"be likely to precipitate",
"have only bright sunshine",
"have empty blue skies",
"be sunny and clear"
] | A | cloudy means the presence of clouds in the sky |
OpenBookQA | OpenBookQA-2417 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
Within an ecosystem, producers are likely to be | [
"liquid",
"bloody",
"diamond",
"budding"
] | D | producer is a kind of role in an ecosystem |
OpenBookQA | OpenBookQA-2418 | thermodynamics, heat-engine
You have your flame power the $`` {\small{\begin{array}{c} \textbf{Hot Water} \\[-25px] \textbf{/ Steam} \end{array}}} "$ stream. This step is how we input the excessive driving force that comes from the flame's unnecessarily high temperature.
You hook up some random waste heat source to the $`` {\small{\begin{array}{c} \textbf{Chilled} \\[-25px] \textbf{Water} \end{array}}} "$ stream. When the contents of this stream go through the $`` \textbf{Evaporator} " ,$ they'll give off their heat to evaporate the heat pump's internal working fluid – and, since the that internal working fluid is stealing the stream's thermal energy, that stream is cooled in the process. This step is where we get the extra thermal energy from.
You hook up whatever you want to heat, like the air to your home or the food you want to cook, to the $`` {\small{\begin{array}{c} \textbf{Cooling} \\[-25px] \textbf{Tower} \end{array}}} "$ stream. As the contents of that stream flow through the absorber, the internal working fluid is reconstituted in an exothermic reaction, warming the contents of the stream. The warmed stream then exits the heat pump, only to reenter it in the condenser. In the condenser, the gaseous internal working fluid condenses on the stream, again dumping heat into it (as condensation is also exothermic).
If you do a thermal-energy balance on the system, you'll see the the thermal energy from the flame and the waste-heat source both ended up warming your home/food/whatever. In effect, you got more thermal energy out of the flame than the flame actually had by using its excess driving force to also harvest thermal energy from a waste heat source.
possibility of a “reverse-refrigerator” that cooks?
The following is multiple choice question (with options) to answer.
Adding heat energy to something can cook it, such as heating | [
"ice",
"wood",
"seashells",
"cookie dough"
] | D | cooking food requires adding heat energy |
OpenBookQA | OpenBookQA-2419 | quantum-mechanics, pauli-exclusion-principle, thought-experiment, quantum-teleportation, quantum-states
Title: Who's states would change first and how? If someone's quantum states were copied a few miles away and a group of particles there were changed to the same states(except position), thus a copy of that person would form a few miles away. If I'm wrong correct me, both groups of particles would still exist at the same time. So lets say we then simultaneously change their positions so they both go to the same position at the same time, therefore the PEP would force them to change states, so which one would change and how? Okay, so I did some research and found a video that answers my question. According to the No Cloning rule, all the information and energy of the original person would need to be extracted but to do so the person would be destroyed. This is not because of the PEP. Then you would be broken down and turned into energy, after that the energy would be used to reassemble you somewhere else.
Video link: minutephysics
The following is multiple choice question (with options) to answer.
Which would alter your position over time? | [
"running in place",
"walking straight",
"jumping up/down",
"sleeping"
] | B | moving changes position |
OpenBookQA | OpenBookQA-2420 | geology
Title: What is this? A sinkhole?
Lat., long.38.47491, 43.48882, in the vicinity of Van in Turkey
I saw this when hiking. I want to know what it is and what are the dangers it poses. Lots of people hike that area in spring and summer, villagers collect edible plants in the area and graze livestock there. This is most likely a small slump scar modified by later erosion. If you look at the feature from a different angle in Google Earth, you will see that it's not even circular. It's more of a teardrop-ey crescent Moon shape, with the concave part downslope from the convex part. The bottom edge and top edge used to match up before the slide.
The following is multiple choice question (with options) to answer.
Which of the following is likely to cause the most erosion? | [
"a babbling brook",
"a mighty river",
"a stagnant pond",
"a light breeze"
] | B | water causes the most soil and rock erosion |
OpenBookQA | OpenBookQA-2421 | the-sun, space, stellar-atmospheres
However, when you have something the Sun or even fog, the optical depth varies with the distance you're looking into that object. I'll talk about fog since it's familiar, but the same idea applies to the Sun's atmosphere. Say you're standing in a forrest and its very foggy out. There's a tree 1 meter away from you that you can see. You could measure your optical depth, $\tau$, of the fog between you and tree and might find that $\tau = 0.15$. Since $\tau$ is less than one, that implies you can see the tree, but the value of $\tau$ also implies how well you can see it. If $\tau = 0$, there's nothing between you and the tree to impede your ability to see it. Let's say there's another tree that's 5 meters away. Now there's more fog between you and the tree and while you can still see it, it is harder to see it. The optical depth of the fog between you and the tree 5 meters away might be $\tau = 0.75$. It's still less than one, implying the tree is visible, but because there's more fog between you and the tree, the optical depth is higher. Finally, there may be a tree 10 meters away with so much fog between you and the tree that the optical depth is $\tau = 1.5$. You can't see this tree because there's too much fog in the way. Hopefully you now realize that anything which is at a distance where $\tau > 1$ is not visible to you. That effectively defines a "surface" around you precisely when $\tau = 1$. Anything beyond that point is not visible and anything closer is visible.
If you're talking about the Sun, you can look at the Sun, but you'll only see light which originates from a point where $\tau < 1$. There are countless photons bouncing around inside the Sun, but you can't see them because they're in an opaque part of the Sun. Astronomers use the optical depth as a metric for defining the "surface" of the Sun.
The following is multiple choice question (with options) to answer.
Which of the following would cause sunlight to better reach the ground of a forest? | [
"more umbrellas",
"logging",
"more trees",
"taller trees"
] | B | large trees block sunlight from reaching the ground |
OpenBookQA | OpenBookQA-2422 | newtonian-mechanics, kinematics, projectile
Title: When I kik a ball at velocity Vo, angle alpha, from the ground..(no air resistance) I have the force acting on the ball equals to F = (Fx,Fy) = (0, -mg)?
I mean I understand that I have the mg force on the y axis, pointing down, and I understand that there is no additional force on the x-axis, but shouldn't I have also a force (both in the x axis and yaxis) that comes from the fact that I kicked the ball?
I mean shouldn't it be something like F = (Fx, Fy) = (ma(x)+0, -mg + ma(y))?
Thanks The usual assumption is that the kick changes the initial condition of the ball. Your foot made contact at $t=0$, and exerted a large force $F$ during a short time interval $\Delta t$. If we assume the force exerted was constant, then at the time the ball leaves the foot, it has momentum $p = mv = F\Delta t$, and it has moved a very short distance $d = \frac12 a t^2 = \frac{F \Delta t^2}{2 m} = \frac{v\Delta t}{2}$; and the shorter $\Delta t$, the less far the ball moved during the kick (for the same velocity).
If you ignore that small amount of motion, then you can say the problem starts when the foot stops making contact with the ball; and you start the calculation with the ball at a certain velocity $v$, only subject to the force of gravity.
The following is multiple choice question (with options) to answer.
A ball can be moved by force when | [
"a dog sees",
"a ball sits",
"a child notices",
"a foot exerts"
] | D | if an object is kicked then force is exerted on that object |
OpenBookQA | OpenBookQA-2423 | thermodynamics
In essence, if we treat lava as a black body radiator with an emissivity of 0.8 (just to pick a "reasonable" value), we can compute the heat flow to an observer. This is essentially a fraction of the heat flow you would have if you were completely surrounded on all sides. This means that if you have a semi-infinite plane of lava, your height as an observer will matter a great deal - if you crouch down, the plane "looks smaller" and you will experience less heat flux. When you stand up, your head will get more heat than the rest of you.
Temperature: radiated power goes as the fourth power of temperature, so this is the most important number to estimate correctly. A 10 % change (say from 800 to 900 C) results in a 40% change in radiation. Google gives values from 800 (Mt St Helens) to 1100 (Hawaiian basalt) so there is a lot of variability here
Reflectivity: assume you wear white clothes (looks better in the movie) you might reflect 80% of the incident radiation
Air flow: if there is a bit of wind blowing to cool you down, that will help. Luckily, if you are on the edge of a lava field, the effect of the heat will be to draw cold air in and then lift it up - so you should have a cool breeze (I have never been near a lava field but I think that's a reasonable speculation)
Toxic fumes: if the above is true, the effect of toxic fumes will be mitigated by the built in "extractor fan" formed by the heat.
Calculating: assume a height $h$ at distance $d$ from a semi infinite plane at temperature $T$:
The following is multiple choice question (with options) to answer.
A mountain top heats and lava flows, resulting in | [
"a hot golden leaf",
"a cold deep sea",
"a raised portion of land",
"a sunken valley of ice"
] | C | a plateau is formed by a buildup of cooled lava |
OpenBookQA | OpenBookQA-2424 | 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 lot of deep dips in an expanse of land could have happened | [
"over a month",
"over a decade",
"over a year",
"over a millennia"
] | D | a canyon forming occurs over a period of millions of years |
OpenBookQA | OpenBookQA-2425 | species-identification, entomology
Title: What is this insect? 6 legs and black spots What is this bug?
Details:
- Georgia, (Southern) USA
- Maybe 1-4cm in size
- Seen near an open area/crack between an outer door-frame and door where it could have come from outside, or going from inside to outside since the temperature difference was noticeable in this area.
Thanks in advance! (Note: I'm going to be using the British English "ladybird" instead of the US English "ladybug" in this answer.)
This is a clearly a species of ladybird. Going by the number of spots, their size and not-perfectly-round shape, the positioning of the four central spots relative to the others, and the fact that its background colour isn't bright yellow... I'm pretty sure it's Harmonia axyridis, the species that us Brits refer to as a "Harlequin ladybird". I think Americans refer to it as an "Asian ladybug" or "Asian ladybeetle".
The spot patterns for this particular species vary a lot, as to some extent do the colours, so I've googled for images to support this answer. The below picture was posted to:
https://en.wikipedia.org/wiki/File:Harmonia_axyridis01.jpg
and is the IP of a user or organisation called Entomart. On the Wikipedia page and on their homepage, Entomart grant permission for the use of the image as long as they are given proper attribution, so I'm able to include it in this answer:
For more pictures of the Harlequin (again, showing how much the spot pattern and colouration vary), see:
https://scx2.b-cdn.net/gfx/news/hires/2018/amechanismof.jpg
For pictures of other ladybird species to compare the Harlequin with - as also one more of the Harlequin:
https://www.naturespot.org.uk/taxonomy/term/19357
Thanks for posting this question! I didn't expect to see a ladybird on Christmas Day :-)
The following is multiple choice question (with options) to answer.
What could be used to examine the legs of a lady bug? | [
"a pedometer",
"a stethoscope",
"a loupe",
"a telescope"
] | C | magnifying glass is used to see small things by making objects appear bigger |
OpenBookQA | OpenBookQA-2426 | safety, equipment
Finally, make sure someone doesn't get the idea that the hood will stop all fumes and try to do a perchloric acid experiment using that hood--that will go badly.
Now, all this being said...
What you really need isn't to make this safe, what you need is to convince administration that you're doing things safely. This may have nothing at all to do with whether things are actually safe or not.
At my old school (where I was briefly president of the local ACS chapter), I could have put an experiment into a fume hood with no filter, not plugged the thing in, and gotten an okay from the administrators because they believed that fume hood = safe and no fume hood = unsafe no matter what else was going on.
I say this not to encourage you to try to trick your way out of this, but to point out that, unless your administration is scientific (i.e. actually understands science), then it's fairly likely you're going to have to jump through a few silly hoops in order to satisfy them.
Best of luck!
The following is multiple choice question (with options) to answer.
A person wanting to protect the environment could avoid | [
"yelping",
"singing",
"smoking",
"breathing"
] | C | An example of protecting the environment is reducing the amount of pollutants |
OpenBookQA | OpenBookQA-2427 | 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.
If something is able to grow from a kernel and insects assist in reproduction, then it is probably a | [
"carnation",
"rock",
"chair",
"dove"
] | A | a flower produces pollen and seeds |
OpenBookQA | OpenBookQA-2428 | carbon-cycle, biogeochemistry, carbon, limestone
The rate of this process is dependent on how much energy you are prepared to throw at it. A fleet of several thousand nuclear reactors running 24/7 on this problem would do it.
Burial
Well, brute force sounds a bit expensive.. so we can try the approach mentioned by Jack R Woods. In this case, we capture CO2 (this still takes energy, although not much in theory), and pump it into thick basalt formations such as the ones in Iceland. Many flood-basalt igneous provinces have the combination of low-silica rocks and high porosity that are ideal for this kind of sequestration. The rate is limited by how fast you can capture CO2 out of the air. You could imagine using a Solar Updraft Tower - this would give an air flow that you could extract CO2 from, and provide power for the process. If the reaction goes as planned, it's safe on geological timescales.
The problem is, as ever, getting enough resources to build these things on the scale required.
The following is multiple choice question (with options) to answer.
The crawling pace of limestone removal from an area produces | [
"giant slugs",
"new crops",
"homes for bats",
"land mines"
] | C | a cavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone |
OpenBookQA | OpenBookQA-2429 | species-identification
Title: What is this (water-loving) bug? For some time we've been finding these little fellows in our apartment:
They seem harmless enough, but finding them is a bit... annoying. I found the fellow above in the bathtub, and it's not uncommon to find more than one.
Unfortunately, some started to appear near the kitchen sink as well. Or outside of the bathroom on the floor (at least that's where we noticed them).
I think this thing prefers darkness over light, and seems to be drawn towards wet places or just water. These critters are also surprisingly fast.
What is it? Should we be concerned about a pest problem, or is this just a minor, unwelcome guest?
PS. We live in Poland. It is a Lepisma saccharina or silverfish.
It is rather common and yes, it's harmless.
The following is multiple choice question (with options) to answer.
A grass snake may make its home in | [
"a jungle",
"a desert",
"a neighborhood",
"a swamp"
] | C | grass snakes live in grass |
OpenBookQA | OpenBookQA-2430 | electricity, electric-circuits, electric-current
I was wearing flip flops from the time I stripped off my neoprene wet suit at the car until the time I started getting shocked (my wife was wearing Birkenstocks).
I had been snorkeling for about an hour in the Pacific Ocean wearing a full body wet-suit, booties, and gloves (no hood).
I had been camping the night before and consumed quite a bit of Gatorade.
My wife had only been wearing a spring suit and gloves, no booties.
There was another receipt that had been left in the machine (maybe someone else had been shocked as well and decided it wasn't worth the risk of going after it?)
I can't think of anything else relevant. Any insights into what was going on here would be welcome. I tried calling the maintainers of the machine but couldn't get through (this was before I found out that I seemed to be the only one affected).
Thanks!
She tried touching the machine in various places, again nothing. I inadvertently touched her hand while she was touching the machine and then suddenly she felt it too.
From this it is evident you were a good conductor to the ground.
You later say :
We came back out 15 minutes later after drinking our hot chocolate and tried to reproduce the phenomenon with no luck.
So no charge was passing through you any longer?
15 minutes is too little a time to change your conductivity. It could be a combination of an intermittent fault in the circuit and your conductivity at that time. You should alert their maintenance to be on the safe side.
The following is multiple choice question (with options) to answer.
A person can know if they need a down vest by checking the | [
"thermograph",
"tunnels",
"graveyard shift",
"sidewalk"
] | A | a thermometer is used to measure temperature |
OpenBookQA | OpenBookQA-2431 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
Which season is it for Australians in July? | [
"Spring",
"Fall",
"Winter",
"Summer"
] | C | seasons cause change to the environment |
OpenBookQA | OpenBookQA-2432 | electromagnetism, electrostatics, magnetic-fields, polarization, dielectric
Example 1. Solenoid of radius $a$ and length $L$ with a electric current $I$ running through it, the interior of the solenoid is partially filled uptil $b<a$ with a material of permeability $\mu$, find $\vec H, B$ in all regions.
The first thing they do is Ampere law to find $\vec H$ with $\oint \vec H\vec dl=I_{free}$ but they separate it from the cases where $r\leq a$ and from cases $r>a$, why? Without even applying anything of boundary conditions, they already know that those $H$ are different at $a$, but for example, not different at the boundary $b$ where the $\mu_0$ changes to $\mu$
Example 2. Between 2 cylindrical conductors of radius $R_1, R_2$, there is a potential applied $V_0$ and there exists 2 different materials with $\epsilon_1$ and $\epsilon_2$ like the picture shows, find $\vec E, \vec D$.
They now know without any boundary condition calculus that $\vec D$ is constant throughout $R_1\leq \rho \leq R_2$ and does not differ from the different dielectrics since thet just do $\oint D\vec dS=D2\pi\rho L=Q$, but now look at the last example
Example 3. Consider a spherical capacitor connected with $V_0$ such that there is a dielectric in half of the space between the spherical conductors like the figure shows, find $\vec E,\vec D$
The following is multiple choice question (with options) to answer.
Which of the following is an example of electrical insulation? | [
"Ethernet cables",
"stove burners",
"movie cameras",
"air conditioning"
] | A | electrical insulation requires wrapping a conductor in an insulator |
OpenBookQA | OpenBookQA-2433 | energy, rotational-dynamics, work
Title: Work Done on a rotating body Hello so I am having an issue with a question I am trying to solve.
The following is multiple choice question (with options) to answer.
A person wants to dry their clothes for work. They seek out some energy that can be continuously gotten without running out, so they dry clothes using | [
"the water",
"the moon",
"the leaves",
"the sun"
] | D | solar energy is a renewable resource |
OpenBookQA | OpenBookQA-2434 | • Interesting! I appreciate you taking the time to note this. As I note in the comments on most of the answers, the mutual definition is but one very restricted interpretation of the original problem, and I desire greatly to see solutions for other interpretations. Thank you so much for your time! – Brevan Ellefsen Oct 4 '16 at 1:52
• You can think of this answer as showing why the "very restricted" interpretation is also the most interesting one. With too little restriction, you can't say anything at all! – Robin Saunders Oct 4 '16 at 2:07
• This was my immediate thought, with a specific example. Imagine a circular hallway, with cats uniformly spaced in the center of the hallway, each looking the same angular direction (so all clockwise or all anti-clockwise). Now, we can change the radius of the circle and the width of the hallway so each cat sees three cats in front of it, but not the fourth one. From there, it should be possible to approximate the circle using a polygon, such that there's one cat in each corner of the exterior wall, and to do so in such a way that the cats still see three other cats. – MichaelS Oct 5 '16 at 3:27
• An interesting question to consider is whether the resulting graph can be connected; the answer depends on the group but also on the choice of generators. For example, most finite simple groups (the "building blocks" of finite groups, like the prime numbers are for integers) can be represented with three generators. There's an interesting slideshow related to this here: www2.warwick.ac.uk/fac/sci/maths/research/events/seminars/areas/… - it's aimed at postgraduates, but contains lots of relevant keywords for you to read about further. – Robin Saunders Oct 5 '16 at 15:20
• Finally, here's a more beginner-friendly, less intense introduction by the legendary Terry Tao: terrytao.wordpress.com/2010/07/10/… – Robin Saunders Oct 5 '16 at 15:33
Building onto Robin Saunders' idea, it is definitely possible that cat A can see cat B but cat B can't see cat A. It's just like kids playing hide and seek closing their eyes - "if you can't see them they can't see you right?"
The following is multiple choice question (with options) to answer.
Two cats in different rooms may share information by | [
"vocalizing",
"sleeping",
"thinking",
"waiting"
] | A | sound can be used for communication by animals |
OpenBookQA | OpenBookQA-2435 | game, objective-c, ai
//otherwise if one can be built, build one
} else if ([self floorsWithRooms].count > 0) {
DTTowerFloor *floor = [[self floorsWithRooms] firstObject];
_moveToPerform = [[DTGameAIJob alloc]initWithFloor:floor.floorNumber AIJobToDo:GamePlayingAIJobTypeRoomUpgrade jobToDo:0 roomType:RoomTypeFarm];
//otherwise expand the tower
} else {
//eventually this will not always happen
self.state = GamePlayingAIStateExpandTower;
}
[self finalizeStateForConcreteMove];
}
-(void) addMoveToMineFloor {
NSMutableArray *floorsNeedingMining = [self floorsForDigging];
if (floorsNeedingMining.count > 0) {
DTTowerFloor *floor = [floorsNeedingMining firstObject]; //add method to pick the closest to 0 or closest to a stockpile
_moveToPerform = [[DTGameAIJob alloc]initWithFloor:floor.floorNumber AIJobToDo:GamePlayingAIJobTypeBasicJob jobToDo:JobTypeMining roomType:0];
}
[self finalizeStateForConcreteMove];
}
-(void) addMoveToBuildLadder {
NSMutableArray *floorsNeedingLadders = [self floorsWithoutLadders];
if (floorsNeedingLadders.count > 0) {
DTTowerFloor *floor = [floorsNeedingLadders firstObject]; //add method to pick the deepest floor
_moveToPerform = [[DTGameAIJob alloc]initWithFloor:floor.floorNumber AIJobToDo:GamePlayingAIJobTypeBasicJob jobToDo:LadderJob roomType:0];
}
The following is multiple choice question (with options) to answer.
A guy is trying to choose a spot to build his house. He chooses a place that will cause the least environmental change in an area, so he builds in | [
"a town",
"a jungle",
"a desert",
"a forest"
] | A | humans building homes in an environment causes that environment to change |
OpenBookQA | OpenBookQA-2436 | human-biology, evolution
Humans are off the charts in the amount of resources we invest in our children - our lives are 1/4 to 1/3 over before we sometimes leave our parents household (in some societies of course they never leave the house, but step into an extended family). This may be one of the reasons we are so successful as a species - we live in practically every place we possibly could and have no danger of competition from any other living thing excepting ourselves.
The grandmother effect is essentially the idea that if women, who are more attached to the offspring in more cases than fathers, continue to live and help support the grandchildren and make them more successful, then this will allow post menopausal women to have a longer lifespan (which they do).
The evolutionary biologist Sara Hrdy, emeritus UC Davis, has written quite a bit about the nuances of the evolution of the role of motherhood - reading some of her articles or books might give you a deeper sense of how profoundly filial love has shaped human beings.
--- more answer this stuff may or may not be worth reading depending on how broadly you want to understand this question...
Its important to say that many of the expansions of human average human lifespan have not been genetic. Its commonly cited that sewer systems, clean water, antibiotics and plentiful food are the three most important factors in human lifespan - and before modern developed world nations, the average lifespan of human beings was somewhere in the 30s. And there are significant lifespan differences in regions where these factors and others (education of women, access to prenatal and early care etc) are available.
Studies continue to be published that examine environmental and lifestyle factors compared to genetics and it seems that environment and lifestyle can make an astounding difference.
But genetics undoubtedly has a role to play here too. There are probably some individual humans and animals which have evolved to live longer. This has been found to be genetically related in some humans by demographics and family lines.
The following is multiple choice question (with options) to answer.
Scientists suggest that, due to human activities, earth has lost waterways and about half of its original forest lands, endangering many animals and plants in their natural living spaces. However, human activity seems to benefit some living things, such as | [
"rats and roaches",
"saunas and pools",
"new phone numbers",
"cotton clothing"
] | A | humans changing animal habitats usually causes harm to those animals |
OpenBookQA | OpenBookQA-2437 | astronomy, everyday-life, popular-science, climate-science
Title: Why is the summer, in the temperate latitudes, in average, hotter that the spring? It is common knowledge that the transition from the Spring to the Summer season occurs in the Summer Solstice when the "Sun reaches its highest excursion relative to the celestial equator on the celestial sphere" (as stated in Wikipedia).
It is also stated in Wikipedia' Summer page:
"Days continue to lengthen from equinox to solstice and summer days progressively shorten after the solstice, so meteorological summer encompasses the build-up to the longest day and a diminishing thereafter, with summer having many more hours of daylight than spring."
My question is: why is the summer, in the temperate latitudes, in average, hotter that the spring? A major part of the reason for this is due to the temperature of the ground. While the length of days in the Summer are effectively a mirror of those in Spring, you must take into consideration more than that.
When Spring commences in temperate climates, it is (usually) immediately preceded by winter. Due to the Winter, the ground and/or surrounding bodies of water are very cold. This has the effect of cooling the air for the first part of Spring while the ground/water begins to thaw/warm up. Furthermore, it takes much longer to warm or cool a body of water than a mass of air; even longer to warm or cool the ground and water. Therefore, as Spring progresses and the days become longer (also meaning the Sun is higher above the horizon, thus providing more heating power), the sunlight must first overcome the cooling effects of the ground and water bodies. Near the end of Spring - when the days are sufficiently long and the Sun is much higher above the horizon - you should notice the weather becoming hotter. This is because the ground and water has had time to warm up, which means it is not constantly cooling the air and making it feel colder.
When you then transition to Summer, the ground is already sufficiently warm but the days are still long and the Sun is still high in the sky. This means the Sun can heat the ground, water, and air even more and without any cooling effects. This allows the Summer temperature to be easily higher than that of the Spring temperatures. If Summer were immediately preceded by winter, you might notice the weather getting warmer much more quickly, but the average temperature would be very close to that of the Spring.
The following is multiple choice question (with options) to answer.
The warmest part of the year happens while | [
"a comet is flying close by",
"mercury is visible in the sky",
"the hemisphere of that region is tilted towards from the sun",
"the hemisphere of that region is tilted away from the sun"
] | C | summer is when a hemisphere is tilted towards the sun |
OpenBookQA | OpenBookQA-2438 | astrophotography
if it is 13 billion light years away wouldn't it take 26 billion light years to take those pictures?
as if light years are a measure of time. A light year is a measure of distance, the distance light travels in a year in a vacuum.
The following is multiple choice question (with options) to answer.
A year can pass in the time it takes | [
"our globe to circle a heat source",
"to heat up a hot pocket",
"to take off your shoes",
"to wash the dirty dishes"
] | A | a complete revolution of the Earth around the sun takes one Earth year |
OpenBookQA | OpenBookQA-2439 | palaeontology, herpetology
Title: How big can cold-blooded animals get? It seems impossible to have reptiles the size of dinosaurs, just because they are really big! Did they have different systems of maintaining body temperature or maybe they weren't the exact type of animals that we today call reptiles? Answer is quite simple as from @Alan Boyd link. They are cold blooded and thus, can go out for hunt in cold, they need to stay put till they get some prey.
So, it mainly depend on the temperature of the outside, I found this interesting paper on relation of body sizes and latitude.
Body sizes of poikilotherm vertebrates at different latitudes
Maximum sizes of 12,503 species of poikilotherm vertebrates were
analyzed for latitudinal trends, using published data from 75 faunal
studies. A general trend appears which may be summarized by the rule
"among fish and amphibian faunas the proportion of species with large
adult size tends to increase from the equator towards the poles". The
rule holds for freshwater fish, deepsea fish, anurans, urodeles, and
marine neritic fish arranged roughly in order of decreasing clarity of
the trend). In general the rule applies not only within these groups
of families but also within single families. In reptile groups, the
rule holds weakly among snakes and not at all among lizards or
non-marine turtles. Possible explanations include an association
between small size and greater specialization in the tropics; the
possibility in poikilo-therms of heat conservation or of some other
physiological process related to surface/volume ratio; selection for
larger size in regions subject to winter food shortages; and an
association between large adult size and high reproductive potential
in cold regions. Other suggestions can be advanced, but all are
conjectural and few are subject to test. Global size - latitude trends
should be looked for in other living groups.
Cite: Lindsey, C. C., 1966: Body sizes of poikilotherm vertebrates at
different latitudes. Evolution: 456-465
Now lets compare some of the largest cold blooded Animals:
Reptiles
Amphibians
Fishes (Pisces)
The following is multiple choice question (with options) to answer.
Living things which require warmth likely also require | [
"beads",
"tea",
"presents",
"kidneys"
] | D | an animal requires warmth for survival |
OpenBookQA | OpenBookQA-2440 | java, reinventing-the-wheel, console, unix
With clothes the new are best, with friends the old are best.
He is truly wise who gains wisdom from another's mishap.
Beware of a dark-haired man with a loud tie.
Today is the last day of your life so far.
Flee at once, all is discovered.
Man who falls in vat of molten optical glass makes spectacle of self.
Go directly to jail. Do not pass Go, do not collect $200.
For a good time, call 8367-3100.
Those who can, do; those who can't, simulate.
Those who can, do; those who can't, write. Those who can't write work for the Bell Labs Record.
God does not play dice.
This fortune is inoperative. Please try another.
Laugh, and the world ignores you. Crying doesn't help either.
No amount of genius can overcome a preoccupation with detail.
You will feel hungry again in another hour.
You now have Asian Flu.
God made the integers; all else is the work of Man.
Disk crisis, please clean up!
You auto buy now.
Many are called, few are chosen. Fewer still get to do the choosing.
Try the Moo Shu Pork. It is especially good today.
Many are cold, but few are frozen.
The early worm gets the bird.
He who hesitates is sometimes saved.
Time is nature's way of making sure that everything doesn't happen at once.
The future isn't what it used to be. (It never was.)
Can't open /usr/lib/fortunes.
If God had wanted you to go around nude, He would have given you bigger hands.
It is better to have loved and lost than just to have lost.
A journey of a thousand miles begins with a cash advance from Sam.
Disk crunch - please clean up.
Center meeting at 4pm in 2C-543
I will never lie to you.
Spock: We suffered 23 casualties in that attack, Captain.
Your computer account is overdrawn. Please reauthorize.
1 bulls, 3 cows
It's hard to get ivory in Africa, but in Alabama the Tuscaloosa.
Waste not, get your budget cut next year.
Old MacDonald had an agricultural real estate tax abatement.
Snow Day - stay home.
Save gas, don't eat beans.
The following is multiple choice question (with options) to answer.
A person wanting to conserve resources in a positive way will | [
"place plastics in special containers",
"leave plastic on the roadside",
"burn plastics in their yard",
"throw away plastic containers"
] | A | recycling resources has a positive impact on the conservation of those resources |
OpenBookQA | OpenBookQA-2441 | mechanical-engineering, structural-engineering, control-engineering
For example, if I wanted to setup such a facility, who would I have to consult?
You either find a consulting engineering firm with a lot of experience in designing and planning (and building!) such a plant. Or you find anexperienced hydroponics expert (the first bullet point) and a consulting firm with experience in a relevant field like wastewater.
Alternativly, you find a company specialized in building and selling hydroponics farms. This will give you less choice over the final plant - the company will want to work with their preferred components and concepts, and crucially they will want to reuse as much egnineering work from previous projects as they can.
The following is multiple choice question (with options) to answer.
A plant that needs to expand will be able to have an endless resource in | [
"dirt",
"pesticides",
"pay",
"beans"
] | A | soil is a renewable resource for growing plants |
OpenBookQA | OpenBookQA-2442 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
Which of the following make sustainable, long term energy? | [
"fossil fuels",
"windmills",
"coal mining",
"fracking"
] | B | wind is a renewable resource |
OpenBookQA | OpenBookQA-2443 | organic-chemistry, everyday-chemistry, experimental-chemistry, biochemistry, food-chemistry
Title: How Bread is made with yeast, sugar and luke warm milk? Materials and Apparatus:
wheat flour
sugar
dry yeast
glass bowl
covering plate
milk
Procedure:
Lukewarm milk is taken in the glass bowl and sugar is added to it. Then, yeast is added to the same.
The mixture is left undisturbed for 10-12 minutes to activate the yeast
3 cups of wheat flour are added to the bowl containing the milk mixture.
The mixture is mixed thoroughly with 100ml of added water and the dough is kneaded well
The dough is placed in a bowl, covered with a plate and left undisturbed for 2 hours.
My query/confusion:
Why is milk needed?
"activated yeast"- what's the difference?
Can yeast work without sugar or milk.
Detail out the stages of the anaerobic oxidative process which takes place as a common first step in both aerobic and anaerobic respiration.
Finally, feel free to share anything I may be missing which should be here.
If you have any confusion regarding what I want to ask, please ask in the comments. Please upvote if you are curious about it too
milk is not needed, 'pure' bread is without milk
yeast is a fungus, therefore, it is alive. Its best to work with fresh yeast, which you find as small cubes in the refrigerated section. This one does not have to be activated. non-fresh yeast is dried, so in order for it to work properly, it has to be undried by adding water, which is called activation.
and 4. As said before, milk is not needed. Sugar however is the food for the yeast, without it, it does nothing. In aerobic breathing, the yeast metabolizes the sugar as we would: sugar + oxygen -> water + CO2. Without oxygen, the yeast resorts to ethanol fermentation: sugar -> alcohol + CO2 (this is, why it is used to make beer or wine). For making bread, we have a mixture of both respirations, which does not really matter, since we are only interested in the CO2, which makes the dough fluffy =) But without sugar, there is no CO2.
The following is multiple choice question (with options) to answer.
Which of these are required in addition to a toaster to make toast? | [
"carpet",
"power plant",
"television",
"satellite"
] | B | a toaster converts electrical energy into heat energy for toasting |
OpenBookQA | OpenBookQA-2444 | terminology, seasons, amazon
Title: Are "rainy season" and "less rainy season" good ways to describe Amazon seasons in English scientific language? I'm a Brazilian native. Here, the English translation to the most didactic way to express the Amazon seasons are: "rainy season", and "less rainy season", because it always rains a lot, but there is a period when there is less. Does anyone know if this is the best way to express this in English scientific language? Dry season
While not being very descriptive, 'dry season' is in general use, even for rainforests (Af Koppen climate, if you will). Example papers using the terminology here.
The following is multiple choice question (with options) to answer.
What is the rainy season in north america? | [
"fall",
"spring",
"winter",
"summer"
] | B | a new season occurs four times per year |
OpenBookQA | OpenBookQA-2445 | Suppose A and B are statements of interest. Suppose we want to say in a short sentence that “whenever A is true, B is true, and that when A is false, we do not claim anything about the truth of B”. We use the word “implies” and state for short that “A is true implies B is true”, and mean the truth relations in the truth table you wrote. For this truth table, it wouldn't be meaningful for a good definition of "implies" to have A is false, B is true, "implies" is true. This would mean we are stating that B is always true, which is a valid claim to make, but not very helpful for a suitable definition of "implies".
Keep in mind we could state a different claim, namely, that “whenever A is true, B is true, and whenever A is false, B is false”. Here we are interested in claiming something about the truth of B when A is false. In this case we use the relation “iff” for short. We use this relation make the brief statement: “A is true if and only if B is true” and mean a different set of truth relations. In particular, A is false, B is false, the relation “iff” is true. Further, A is false, B is true, "iff" is false.
Now when you substitute “real” phrases for A and for B, you have to understand clearly what you are stating. Let’s say A is “Sticking a fork in an electrical outlet” and B is “you will get hurt”. Stating “A implies B” is the same as claiming that “if you stick a fork in an electrical outlet, you will get hurt”. This claim may not in reality be true, but that point is irrelevant to the statement from a logical point of view. The key point is that you are claiming nothing about getting hurt if you don’t stick a fork in the outlet. So in short, at this point it’s a matter of defining suitable definitions for useful relations, not about physical reality. Later of course we can do experiments, observe Nature, etc. to test if our claims hold up.
The following is multiple choice question (with options) to answer.
Which is true? | [
"the moon is a source of light with powerful nuclear reactions",
"the sun is a source of evil with powerful nuclear reactions",
"the sun is a source of light with weak, low-temperature reactions",
"the sun is a source of light with powerful nuclear reactions"
] | D | a star is a source of light through nuclear reactions |
OpenBookQA | OpenBookQA-2446 | zoology, behaviour, mammals, rodents
Title: Why do Guinea Pigs chirp / sing? Ok, so this appears to be quite a mystery. Me and my girlfriend have 2 Guinea Pigs, 1 male and 1 female.
My girlfriend once picked up the female one and took her outside into our garden. The Guinea got scared for some unknown reason and jumped out of my girlfriend's arms and fell down hard.. That night, the female Guinea woke us up with some very strange sounds. She sounded like a chirping bird.
Since then, she sometimes repeats these sounds (most often at night, but not always). Mostly, we are puzzled as to why as there is often no apparent reason for her sounds. Also, when she makes the sounds, she appears to be in a trance-like state, making no movements at all.
Looking for the answer online I found many discussions on the subject like this one or this one. Mostly, the sounds (and the often mentioned trance like behavior) appear to be interpreted as either (1) alarm sounds, (2) loneliness sounds or (3) happiness sounds.
There are also recordings of it one Youtube, like this one.
What I was wondering:
Does anybody know about some actual research that has been committed on this subject? If so, what were the results?
I'm just so very curious to find out! I found this question very interesting so I did some research. Here's a brief summary of what I've found:
Researchers have found that there are 11 different call types. Some of these include a "sharp alarm cry", "sociable clucking", chutter, whining, purring etc. Using body position and behaviour, researchers attempted to associate these vocalizations with behaviour. Some vocalizations had no apparent associated action including what researchers designated the "chirrup" ( I think this is similar to what your guinea pig might have emitted.)
For more information you can read the results section of this paper by Berryman. You can find a full description of each of the 11 calls and their assumed cause or purpose. Some involve social interaction, reproduction, and distress. Much of the research regarding Guinea pig vocalization involves communication and response between mothers and pups.
In short, it seems as though this chirping behaviour your Guinea pig is exhibiting is normal, but not of any known cause.
The following is multiple choice question (with options) to answer.
A small rodent will fear a creature such as a fox because | [
"foxes enjoy rodent dinners",
"foxes are very small",
"squirrels eat mostly beans",
"mice are able to fly"
] | A | predators eat prey |
OpenBookQA | OpenBookQA-2447 | zoology, marine-biology
Title: Why do stranded marine mammals die so quickly? Mammals have lungs, so do marine mammals. Nevertheless some marine mammals seem to die rather quickly when they strand on a beach.
As they have lungs and can breath while on land, why do they die so quickly? Not being in water only restricts them from food.
Do they maybe try to get back into the water so rudely that they get hurt by rocks and/or break bones? Pressure difference doesn't seem to be a problem as they can jump out of the water as well.
I was wondering after reading this article on stranded pilot whales that got spot but died rather quickly after. In the case of whales, I always thought that it was something to do with the fact that they rely upon buoyancy to support their weight and this seems to support that view:
When whales, including small whales or dolphins become stranded on beaches
they suffer from the pressure of their own weight on their organs,in the
water they are weightless. They also suffer from overheating as they have
blubber that insulates them in the water and outside of the water causing
them to overheat. This is why we place wet towels and cold water on their
fins and flukes when do they strand to help keep their body temperature
down. Unfortunately most stranded whales do not survive once they have
beached themselves.
The following is multiple choice question (with options) to answer.
Where would a short-beaked animal likely die? | [
"in a habitat with only insects who live in tight spaces",
"in a habitat with lots of fruits and nuts",
"in a habitat where it is fed and cared for",
"in a habitat with plentiful insects"
] | A | the ability to acquire resources has a positive impact on an organism 's survival |
OpenBookQA | OpenBookQA-2448 | food, decomposition
Title: Worm compost cannot have cooked food I live in the Netherlands and it is getting fashionable to compost with worms. After investigating a few websites I noticed that most websites suggested that I cannot feed the worms leftovers from citrus fruits. This seems logical. I then started noticing that people advise against feeding the worms cooked food.
I'm no biologist but I cannot imagine a reason why cooked food is bad for the worms. Could anybody explain why this might be in layman’s terms? There are a few reasons for not feeding cooked foods to worms (Eisenia spp.) in a smaller household size worm farm. It's not because the food is cooked but what it often contains.
The earthworm used in vermiculture is usually Eisenia fetida (red wigglers) though other Eisenia species are sometimes used. All Eisenia are epigeic species meaning they live in the junction of decomposing organic matter (such as leaf litter, aging manure, rotted fallen trees) and their natural food is decaying plant matter and bacteria that are also digesting the organic matter. They don't make use of small dead animals (meat and fat).
In large scale commercial vermiculture operations, leftover and past-due-date foods from restaurants, institutions, nursing homes and schools are used along with plant matter and carboard and paper. I'm not sure how they balance cooked foods but possibly much less is used than plant matter.
The fact food is cooked isn't the problem but what's in it and/or what happens to it when added to the bin. If you have leftover vegetables and fruit that's been cooked with no added salt, it's perfectly acceptable. A certain amount of sweetened cooked fruit is also fine as the worms will eat that too. But ready-made foods usually have preservatives, salt, fats and spices added. Either worms won't eat it, leading to odour caused by mouldy rotten food, or it can make them unthrifty and even killing off your worms if it's fed them repeatedly.
The following is multiple choice question (with options) to answer.
The more that worms make their way through compost, the more | [
"bees in skies",
"vitamins in dirt",
"trees in fields",
"snakes on planes"
] | B | decomposition increases the amount of nutrients in the soil |
OpenBookQA | OpenBookQA-2449 | genetics, gene-expression, human-genetics, mitochondria, gene
Title: Father with mutated mtDNA- why isn't his offspring at risk? Mothers transmit their mitochondria (and therefore mtDNA) to their offspring and fathers don't. Lets assume that father had a mutation of the gene that encodes mtDNA, would then be his offspring at risk? Why?
I also found the following statement:
"The current genetic advice is that fathers with mtDNA mutations are at no risk of transmitting the defect to their offspring."
How can that be true? Is it because of gene silencing?
Thank you in advance!
...would then be his offspring at risk? Why?
No. Generally speaking, fathers do not pass on their mtDNA (Mitochondrial DNA).
Why? Because the mitochondria present in oocytes (egg cell) is the mother's, as every oocyte directly inherits the mother's mitochondria when they are made in the reproductive organs. The mitochondria that the sperm from the father carry to the egg do not enter the egg cell or are destroyed in the process.
It's also worth mentioning that, in general, mtDNA does NOT reside in the nucleus of cells, but in the mitochondria itself. It is not condensed during cell division, it is not spliced during Meiosis II, and it does not undergo recombination with another cell's mtDNA. Instead, when a cell divides, each cell takes about half of the mitochondria present in the cell and maintains them. That way only the mitochondria present in the cell before division will be inherited by the daughter cells, and thus only the maternal mitochondria present in oocytes (egg cells) before sperm instigate cell division will be inherited by any offspring.
The following is multiple choice question (with options) to answer.
A parent contributes DNA to their offspring which can result in | [
"beads",
"freckles",
"frowns",
"dirt"
] | B | DNA is a vehicle for passing inherited characteristics from parent to offspring |
OpenBookQA | OpenBookQA-2450 | # Thread: physics tourist & bear problem
1. ## physics tourist & bear problem
another easy one i think:
A tourist being chased by an angry bear is running in a straight line toward his car at a speed of 3.5 m/s. The car is a distance d away. The bear is 27 m behind the tourist and running at 6.0 m/s. The tourist reaches the car safely. What is the maximum possible value for d?
how many meters?
thanks alot.
2. Originally Posted by rcmango
another easy one i think:
A tourist being chased by an angry bear is running in a straight line toward his car at a speed of 3.5 m/s. The car is a distance d away. The bear is 27 m behind the tourist and running at 6.0 m/s. The tourist reaches the car safely. What is the maximum possible value for d?
how many meters?
thanks alot.
The maximum value of d is such that the bear gets to the car at the same time the tourist does.
So set up a coordinate system such that the bear is at the origin and positive x is in the direction from the bear to the tourist.
Both are moving at a constant speed. The bear has to cover 27 + d meters in the same time the tourist covers d meters.
So for the tourist:
[tex]d = v_t t = 3.5t[tex]
Thus
$t = \frac{d}{3.5}$
For the bear:
$27 + d = v_b t = 6 \left ( \frac{d}{3.5} \right )$
Now solve for d.
-Dan
3. Hello, rcmango!
Another approach . . .
A tourist being chased by an angry bear is running in a straight line
toward his car at a speed of 3.5 m/s. .The car is a distance $d$ meters away.
The bear is 27 meters behind the tourist and running at 6.0 m/s.
The tourist reaches the car safely.
What is the maximum possible value for $d$?
The tourist has a 27-meter headstart.
Relative to the tourist, the bear has a speed of 2.5 m/s.
To cover 27 meters, it takes the bear: . $\frac{27}{2.5} \:=\:10.8$ seconds.
The following is multiple choice question (with options) to answer.
Two bears, one weighing 200 pounds and another weighing 150 pounds are about to enter winter. The bear with the most weight will be | [
"better able to fly",
"more likely to starve",
"better suited to survive",
"more likely to hurt"
] | C | fat is used to keep animals warm |
OpenBookQA | OpenBookQA-2451 | 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 natural illumination outside will be for shorter and shorter periods of time per day when | [
"during a solar eclipse",
"spring season has begun",
"a hurricane is approaching",
"in late September north of the equator or late March south of the equator"
] | D | when the seasons change from the summer to the fall , the amount of daylight will decrease |
OpenBookQA | OpenBookQA-2452 | materials
The image is a modified version of an image found at www.geology.um.maine.edu. Original credit: Passchier and Trouw, pg 33 (2005).
The following is multiple choice question (with options) to answer.
A rock quarry can contain in its rocks | [
"sunflowers",
"foil material",
"candles",
"broken toys"
] | B | rocks sometimes contain aluminum |
OpenBookQA | OpenBookQA-2453 | fluid-dynamics, conservation-laws, continuum-mechanics
So -- when you can, pick conservation form because then you only need to numerically-hack your problem for a few terms instead of all of them. The fewer places you can add non-physical things, the better the end result will be!
The following is multiple choice question (with options) to answer.
Which would be a good example of conservation? | [
"smoke stacks",
"littering",
"shorter showers",
"car travel"
] | C | An example of conservation is not using fossil fuel |
OpenBookQA | OpenBookQA-2454 | climate, seasons, ice-age, axial-obliquity
Image originally from The Petroleum System Blog
Using that formula, the temperature at the poles (reduced to sea level) would be -16.8 °C (from the figure actual data points it can be seen that in real life the south pole is much colder than the north pole).
Now, the previous assumptions contradicts the requirement of "equilibrium", because the above scenario is far from steady state.
So now I will go on to try to describe what would happen to Earth's climate in your hypothetical scenario:
One thing that we learned by studying how the Milankovitch cycles trigger and reverse Pleistocene ice ages, is that to initiate an ice age cold winters are not necessary, what is needed are cold or mild summers.
Currently, the inclination of Earth axis (a.k.a. obliquity) varies between 22° and 24.5° , with a mean period of 41,040 years. When the inclination is 22°, mild summers occur and, therefore, the perfect condition to initiate an ice age (specially when combined with other ad-hoc orbital conditions). The permanent equinox situation you propose, is equivalent to an obliquity of 0°, that would lead to the coldest possible summer (this is, no summer at all). Therefore, such condition would set the Earth on track for an intense and never-ending ice age.
Let me explain how this could work: Using the formula above, the temperatures would be permanently below zero between the poles and latitudes 58.3°. Therefore, snow would start to accumulate in those areas, building an ice sheet and once the ice sheet gets thick enough it would start flowing outwards.
Figure from Lumen Learning.
The ice sheet then becomes self-sustaining due to two positive feedbacks:
Due to its high albedo, it would reflect most of the solar radiation back to the space, cooling down the Earth.
As the ice sheet advance, its thickness adds to the elevation of the terrain, therefore the surface is higher and colder, allowing snowfall beyond the 58.3° of latitude. The thicker it grows the more it can advance towards the equator.
The following is multiple choice question (with options) to answer.
The continents currently experiencing winter will be the ones which are | [
"facing the sun",
"distant from sun",
"nearest the sun",
"bathing in sun"
] | B | winter is when a hemisphere is tilted away from the sun |
OpenBookQA | OpenBookQA-2455 | audio, modulation, frequency-modulation, fsk
well, "best" is always a reduction to a single set of optimization parameters (e.g. cost per bit, durability, ...) and isn't ever "universally true".
I can see, for example, that "large" is already a relative term, and for a small office, the optimum solution for backing up "large" amounts of data is a simple hard drive, or a hard drive array.
For a company, backup tapes might be better, depending on how often they need their data back. (Tapes are inherently pretty slow and can't be accessed at "random" points)
So I figured I can store a relatively large amount of data on a cassette tape.
Uh, you might be thinking of a Music Casette, right? Although that's magnetic tape, too, it's definitely not the same tape your first sentence referred to: It's meant to store an analog audio signal with low audible distortion for playback in a least-cost cassette player, not for digital data with low probability of bit error in a computer system.
Also, Music Cassettes are a technology from 1963 (small updates afterwards). Trying to use them for the amounts of data modern computers (even arduinos) deal with sounds like you're complaining your ox cart doesn't do 100 km/h on the autobahn.
But after reading up about it for a bit it turns out that they can store very small amounts of data. With baud rates varying between 300 to 2400 something between ~200KB to ~1.5MB can be stored on a 90 minute (2x45min) standard cassette tape.
Well, so that's a lot of data for when music-cassette-style things were last used with computers (the 1980s).
Also, where do these data rates drop from? That sounds like you're basing your analysis on 1980's technology.
These guys can store 90 minutes of audio. Even if we assume the analog audio quality on them was equivalent of 32Kbps that's about 21MB of data.
The following is multiple choice question (with options) to answer.
A guy wants to be able to remember the evening. He can be sure that he has a visual and audio backup of the night by | [
"bringing his camera",
"bringing his son",
"bringing a drink",
"bringing a chair"
] | A | a camera is used for recording images |
OpenBookQA | OpenBookQA-2456 | 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.
Where would you find the most sunlight? | [
"England",
"Morocco",
"Sweden",
"Norway"
] | B | a desert environment usually has a lot of sunlight |
OpenBookQA | OpenBookQA-2457 | quantum-mechanics, optics, photons, quantum-optics, thought-experiment
Update So in searching a reliable way to make the estimation, I found this discussion where different approaches are given. I think this is better than any estimation I can sketch at this point.
As for the feasibility of all this, I think the closest you would get is having a material with very high reflection for a wide range of the EM spectrum, but still will absorb a fraction, even a tiny one. Thus it would heat up and radiate part of the energy to the exterior, until some stationary situation is achieved where a balance is determined by the actual values of the absorption/reflection coefficients.
The following is multiple choice question (with options) to answer.
Which is likely to be reflecting the most light? | [
"a desert landscape",
"a forest landscape",
"an arctic landscape",
"a rural landscape"
] | C | snow falls during the winter in the arctic environment |
OpenBookQA | OpenBookQA-2458 | 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.
Where would an archaeologist likely find an impression of an ancient footprint? | [
"lying on the beach",
"under layers of dirt",
"on the surface of the moon",
"buried in a graveyard"
] | B | An example of a fossil is a footprint in a rock |
OpenBookQA | OpenBookQA-2459 | zoology, mathematical-models, software, imaging
Title: What would it take to recognize a deer by its photo? I am trying to recognize a deer by its antlers or any other means.
Elaborating:
I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so it would be difficult to recognize it from the last year's photo unless these antlers retain the same pattern every year.
If not the antlers, what other characteristics should I be looking for?
Is there any software that can help me in recognizing a deer? There is a lot of variation in how and when deer shed their antlers. In most arctic and temperate-zone species, antler growth and shedding is annual, and is controlled by the length of daylight. In tropical species, antlers may be shed at any time of year, and in some species such as the sambar, antlers last several years. Some equatorial deer never shed their antlers.
The horns change every year and, especially, increase the number of branches (and consequently, change their shape). You can't recognize them by antlers, but by other features, such as color of the hair or the lineaments. Like us, animals have individual morphological differences that are recognizable and listable.
Biologists specializing in studies of particular animal species not only take photos, but also make drawings and write descriptions of behavior, to identify individuals within herds.
An optical examination, however, of the subject through drawings and photos (and if possible, direct observation), is more useful than a PC program. This involves identifying particular similarities and equalities that are not "identical". This is possible to do visually on a large (but limited) number of specimens. The human eye is the best computer.
The following is multiple choice question (with options) to answer.
Deer can be responsible for which activity? | [
"building office buildings",
"pollution",
"transporting seeds",
"hunting bears"
] | C | if seeds stick to the fur of an animal then that seed will be transported by the animal |
OpenBookQA | OpenBookQA-2460 | reproduction, human-genetics, human-genome
I missed the "as a species" part of your question. Inbreeding will only likely have an effect within small, closed populations, though it will continue to have a lasting effect even as those populations grow and open up. Two textbook examples are French Canadians and Ashkenazi Jews. Even now, there is continued elevated risk of certain rare genetic diseases in these populations. As for the species as a whole, it is likely to be really detrimental only if the effective population size of the species becomes really low: a general rule of thumb used by conservation biologists is that the effective population size should be at least 50 to avoid the effects of inbreeding (and 500 to avoid the effects of genetic drift) (50/500 rule).
Sorry about the confusion.
The following is multiple choice question (with options) to answer.
How low must be a population of some species drop before it is extinct? | [
"fifteen",
"ten",
"to nothing",
"eighty"
] | C | if a population decreases to zero then that organism is extinct |
OpenBookQA | OpenBookQA-2461 | classical-mechanics, work, everyday-life, biophysics
Edit-2: Reactions to some more comments and replies, added some emphasis to provide structure to wall of text
C) No, I am not arguing that descending is subjectively less exhausting, I am asking why it is less exhausting when the mechanics seem to indicate it shouldn't be.
D) There is no "free" or "automatic" normal force emanating from the stairs that stops you from accelerating.
The normal force provided by the mechanic stability of the stairs stops the stairs from giving in when you step on them, alright, but you have to provide an equal and opposite force (i.e. from your legs) to decelerate your center of gravity, otherwise you will feel the constraining force of the steps in a very inconveniencing manner. Try not using your leg muscles when descending stairs if you are not convinced (please use short stairs for your own safety).
E) Also, as several people pointed out, we as humans have no way of using or reconverting our stored potential energy to decelerate ourselves. We do not have a built-in dynamo or similar device that allows us to do anything with it - while descending the stairs we actually have to "get rid of it" in order to not accelerate uncontrollably. I am well aware that energy is never truly lost, but also the "energy diversion instead of expenditure" process some commenters suggested is flawed (most answers use some variation of the argument I'm discussing in C, or "you just need to relax/let go to go downhill", which is true, but you still have to decelerate, which leads to my original argument that decelerating mathematically costs exactly as much energy as ascending).
F) Some of the better points so far were first brought up by dmckee and Yakk:
The following is multiple choice question (with options) to answer.
Which of the following would require more effort to move? | [
"Venus",
"the Sun",
"a dog",
"100lb weight"
] | B | as the mass of an object increases , the force required to push that object will increase |
OpenBookQA | OpenBookQA-2462 | combustion
Title: Why are fires smokey? Combustion, in chemical terms, is a reaction with a certain molecule and oxygen, and it produces, energy, $\ce{CO2}$, and $\ce{H2O}$ (That's how I learned it at least). So what makes a fire'smokey'? I had always thought that smoke was simply $\ce{CO2}$, but read that it was actually the result of incompletely 'combusted' material, yet I don't fully understand what this means. Is smoke made from material that starts to combust but stops before it finishes, or does it never even begin combustion? What would the chemical reaction be of a wood (Or other similar) fire that produces a lot of smoke? And finally, is there a certain element or compound that gives smoke its 'smokey' smell? Smoke is essentially aerated ash, unburned organics (including charcoal) and steam. You have to remember wood is not a pile of cellulose, but the remains of a dead organism. All the essential minerals that the plant needed for life are still in the wood such as calcium, phosphorous, sodium and potassium (namely potassium). When the organic matter is fully combusted, water and carbon dioxide are produced and the other elements are left as ash which can become aerated. When the water vapor reaches the cool air it condenses into a visible steam. However in real life wood is not fully combusted, but rather many unburned organic compounds due to a limited amount of oxygen, which give it its smell and fine aerated particles of charcoal which is scentless but very dark. This presence of unburned hydrocarbons in smoke is the cause of backdrafts in firefighting and can be demonstrated by lighting the smoke of a candle that has been blown out.
The following is multiple choice question (with options) to answer.
A dry bush may burst into flames due to | [
"raining skies",
"wetter air",
"higher temps",
"faster birds"
] | C | high temperatures can cause an object to combust |
OpenBookQA | OpenBookQA-2463 | human-anatomy
Taken from here such people would be able to dislocate then get their hands in front and relocate.
The body can be trained to be quite flexible through training like gymnastics etc...
The following is multiple choice question (with options) to answer.
A person wanting to relocate a boulder with their body will need to apply | [
"song",
"exertion",
"love",
"thought"
] | B | pushing an object requires force |
OpenBookQA | OpenBookQA-2464 | zoology, ichthyology, marine-biology
Switek goes on to to talk about exceptions in some marine mammals:
At this point some of you might raise the point that living pinnipeds like seals and sea lions move in a side-to-side motion underwater. That may be true on a superficial level, but pinnipeds primarily use their modified limbs (hindlimbs in seals and forelimbs in sea lions) to move through the water; they aren’t relying on propulsion from a large fluke or caudal fin providing most of the propulsion with the front fins/limbs providing lift and allowing for change in direction. This diversity of strategies in living marine mammals suggests differing situations encountered by differing ancestors with their own suites of characteristics, but in the case of whales it seems that their ancestors were best fitted to move by undulating their spinal column and using their limbs to provide some extra propulsion/direction.
The following is multiple choice question (with options) to answer.
Seals which return to where they were born display reproductive behavior by using that space to | [
"hunt squirrel",
"retrieve eggs",
"birth young",
"kill birds"
] | C | An example of a reproductive behavior is salmon returning to their birthplace to lay their eggs |
OpenBookQA | OpenBookQA-2465 | python
def listen():
global loop_int, last_track
threading.Timer(loop_int, listen).start()
if it.player_state() == k.playing:
# check to see if track was restarted
if it.player_position() < getSec(it.current_track.time())/2 and last_track == it.current_track.persistent_ID():
self.last_track = '0'
# has the track played beyond the halfway mark?
if it.player_position() >= getSec(it.current_track.time())/2 and last_track != it.current_track.persistent_ID():
today = datetime.datetime.today()
now = '{}-{}-{} {}:{}:{}'.format(today.year, '%02d' % today.month, '%02d' % today.day, '%02d' % today.hour, '%02d' % today.minute, '%02d' % today.second)
print '\nArtist: {}\nTrack: {}\nAlbum: {}\nGenres: {}\nDatetime: {}'.format(it.current_track.artist().encode('ascii','ignore'), it.current_track.name().encode('ascii','ignore'), it.current_track.album().encode('ascii','ignore'), it.current_track.genre().encode('ascii','ignore'), now)
last_track = it.current_track.persistent_ID()
addTrack(it.current_track.persistent_ID(), it.current_track.name(), it.current_track.artist(), it.current_track.album(), it.current_track.genre(), it.current_track.played_count(), it.current_track.skipped_count(), it.current_track.year(), now, it.current_track.rating())
The following is multiple choice question (with options) to answer.
A person wants to turn on an MP3 player, so they complete a circuit by | [
"pressing a button",
"singing to it",
"making a face",
"crossing their fingers"
] | A | pushing a button sometimes completes a circuit |
OpenBookQA | OpenBookQA-2466 | adaptation
Title: How do longleaf pine trees adapt to the florida keys rainforest? I know that longleaf pine trees can be found in rainforests, but I can't find anything. This is sort of a too broad question but here are a few ideas. The second most fragile part of plants are the leaves. In the latitudes and elevations that experience freezing, plants have learned to abscise their leaves and go dormant for the winter season. Conifers have thick, waxy, very thin leaves that most conifers do not need to shed.
In a rainforest there is no danger of too cold temperatures. That is why there is an abundance of broadleaf trees and plants in the rainforest. Most of our indoor plants are tropical rainforest species.
There is also an awful lot of rain in a rainforest. There is a problem with leaves covered with water, as it inhibits the absorption of CO2. Beneath the leaf, O2 is released as a by-product of photosynthesis. Broad leafed plants that have adapted to an environment with lots of rain, little wind, and being crowded together have leaves designed to 'wick' the rain water off the leaf to run down the midrib and off the pointy tip or lobed or curled under leaf margins. This clears off the water and allows the plant to take up CO2, or it would not be able to do photosynthesis to make its own food for energy.
The other cool thing I can remember, is that broad leafs of plants are able to 'adjust' to the light. Similar to a 'solar sail' in outer space. If in full sun, those leaves get thick and stay smaller. If in shade, very normal in a rainforest, those leaves can thin and get larger in order to capture as much light as possible.
A better wording for your question would be, 'why is there an abundance of broad leaf species versus conifers in a rainforest'? If I've been able to translate your question correctly?
Hope this helps.
The following is multiple choice question (with options) to answer.
When a forested area receives very little rain, the tall plants in that area | [
"shoot up in height",
"learn to drink saltwater",
"grow so much stronger",
"show thinner age markings"
] | D | as the amount of available water decreases , tree-growth rings will become narrower |
OpenBookQA | OpenBookQA-2467 | electric-circuits, home-experiment
Title: Why does this circuit work and the other doesn't?
if we connect the set up like this the bulb glows but if we connect the [right wire] to the [earth of the left] then the bulb [doesn't glow].
Why does that happen?
if we connect the set up like this the bulb glows
If the pin positions in the photo are
Ground
Neutral Line
And you are in a country where
the neutral is linked to ground at the main panel
but where protective devices such as GFCI or RCD are not used.
Then you have a path for current to flow from Line via Ground to Neutral.
if we connect the [right wire] to the [earth of the left] then the bulb [doesn't glow].
Connecting to the ground of the left socket instead of the ground of the right socket should produce the same result if the socket is wired correctly.
The fact that it doesn't light the lamp suggests either that you made an error in your improvised unsafe connection (the connectors inside those sockets are designed for use with solid metal pins with a specific range of dimensions, not for poking stranded wire into) or that
your socket is badly designed, badly manufactured, badly installed or is damaged. The two ground connectors are not properly connected together internally.
To verify this you could carry out a ground loop impedance test using a suitable Category-II test instrument (isolate the circuit line conductor first using circuit breakers or equivalent at main panel).
The following is multiple choice question (with options) to answer.
A light that is turned on will be connected to wiring, which will | [
"be shredded",
"feel toasty",
"be wooden",
"be icy"
] | B | electrical current running through a wire causes that wire to heat up |
OpenBookQA | OpenBookQA-2468 | newtonian-mechanics, forces, free-body-diagram
Title: How can I actually push heavier objects? I've been thinking about Newton's third law lately because I couldn't understand a few things and I think I actually answered my own question. Could someone confirm if my reasoning is right or show me my mistakes?
So the question is: If force and reaction force are always the same, and less mass means greater acceleration, how can I actually push heavier objects? Then I got my idea of an answer that I will try to show with a picture:
I exert $F_{\text{action}}$ force on a Box (much heavier than me) and an equal $F_{\text{reaction}}$ is exerted on me in the opposite direction, but $F_{\text{action}}$ is caused by the $F_{\text{muscle}}$ force which is exerted on me and has the same direction as $F_{\text{action}}$
The box changes position but I don't change position myself because $F_{\text{muscle}}$ still acts and prevents it.
Step 1 is repeated and that way I can push much heavier objects.
(I am sorry that box looks little different in every step. It was hand-drawn - the box in steps 2 and 3 is meant to be in the same position)
The following is multiple choice question (with options) to answer.
What is most likely to push objects? | [
"rivers",
"rainfall",
"photosynthesis",
"sunlight"
] | A | flowing liquid can push objects |
OpenBookQA | OpenBookQA-2469 | meteorology, geophysics, tropical-cyclone
Title: What is the largest hurricane possible? With Earth getting hotter and hurricanes also getting larger I wonder; Is there a limit on how big a hurricane can physically get? I am going to take an educated guess here because it is not possible(AFAIK) to accurately predict with any known skill what several decades into the future would be like.
Given that premise the largest hurricane in the future could be the size of the tropical extent of the Pacific Ocean or the Atlantic Ocean(wherever that begins and ends). Here I am only considering the Northern(or Southern) tropical extent of the Pacific or Atlantic Ocean because as we know a tropical cyclone cannot cross the equator as explained in this in depth answer Impossible or improbable? Hurricane crossing the equator. The thought process behind this idea is that hurricanes(tropical cyclones) dissipate on coming contact with land. Hence the maximum area of the largest cyclone in the future would have to be the ocean body maximum tropical extent(typically sea surface temperature (SST) greater than 27 degrees centigrade). Just in case if people are wondering why just the tropical extent and why not more than that ? It is because once you enter into mid latitude regions frontal processes could kick in(cold core cyclones-as an example -Can a tropical cyclone form in mid latitude oceanic waters?)
So if the tropical extent of the biggest oceans increases in the future one can imagine a very large possibly synoptic scale tropical cyclone.
Here I am excluding the North Indian Ocean basin because it does not have the surface area to compete with the North Pacific or North Atlantic
Secondly from this popular science article -How strong can a Hurricane get? and this one Are Category 6 Hurricanes coming soon ?
By the end of the 21st century, human-caused global warming will likely increase hurricane intensity, on average, by 2 to 11 percent, according to a review by NOAA's Geophysical Fluid Dynamics Laboratory, revised on Aug. 30, 2017.
followed by
The following is multiple choice question (with options) to answer.
A hurricane will develop largest nearer a sea because of | [
"water color",
"liquid amounts",
"water smell",
"fluid uiclarity"
] | B | an ocean is a source of heat and moisture for a hurricane |
OpenBookQA | OpenBookQA-2470 | ecology, behaviour, sociality, predation, community-ecology
Title: How selective are wolves about the size of their prey? For an animal that lives and hunts socially like a wolf, is there a lower threshold to the size of prey items they will hunt? A pack wouldn't have much trouble with catching say a rabbit, but would the food provided be enough to actually make the hunt worthwhile? What is the limit in which a prey item becomes too small to be worth catching? You should not post here until you've demonstrated your own research effort. Given this stipulation -- and the rich literature about this very topic -- I will keep my answer cursory so as to act as starting points for your search. A simple Google or google Scholar search on your part will reveal many more details/studies.
You should review the following ecological concepts: prey switching, optimal foraging theory, principle of allocation, and others.
Some accessible articles on Prey-to-predator-size ratio include: Henriques et al. 2021, Tsai et al 2016, Cohen et al 1993, and Vézina 1985
Regarding wolves:
According to Becker et al 2018:
[Wolf] Prey selection is influenced by the absolute and relative abundances of prey types, the life history characteristics of predators and prey, and the attributes of the environment in which these interactions occur.
Smith et al. 2010 demonstrate that diets vary with season -- their focus being on winter diets.
Huggard 1993 shows the impact of environmental variables such as snow.
Herd density plays a significant role:
Sand et al. 2016
Davis et al 2012 showed that lower density of secondary prey mattered more than heightened density of primary prey.
Huggard 1993 (Canadian Journal of Zoology) showed that density of herds (vs herd density) mattered more in Banff National Park in Canada. Herd size and habitat also mattered -- with wolves avoiding some habitats and seemingly choosing places that optimized preferred habitats and large herd size.
Wolf scat/diet studies showing smallest species in their diet:
Sin et al 2019: smallest for Sandanavian wolves = domestic dogs
Nowak et al 2011 showed the following small prey made up the stated percentages of wolve's diets in Poland:
brown hare Lepus europeus (2.5%) and Eurasian beaver Castor fiber (1.4%). Domestic animals, exclusively dogs and cats, made up 1.0% of food biomass.
Works cited:
The following is multiple choice question (with options) to answer.
Which animal will hide the best when seeking food | [
"rabbit",
"chameleon",
"cat",
"spider"
] | B | camouflage can be used for hunting for food |
OpenBookQA | OpenBookQA-2471 | evolution, ornithology, palaeontology
One thing those many, many bird and proto-bird fossils also made clear is that the traits of modern birds (feathers, wings, toothless beaks, etc) didn't evolve in a simple line from non-bird to bird. Many of those traits evolved convergently in several lineages, were lost in some, maybe regained in others, and feathers in particular turn out to be a widespread dinosaur feature that cannot be considered a uniquely bird trait anymore (unless we want to call T-rexes "birds"). Still, saying "beaks evolved several times" or "feathers evolved several times" doesn't mean that birds, let alone modern birds, evolved from several different ancestors. It can mean that the common ancestor of birds had lots of variously bird-like more-or-less distant cousins living around the same time.
The following is multiple choice question (with options) to answer.
Which describes the proper usage of bird beaks? | [
"skinny beats are best for sucking blood, fat beaks eat only eggs",
"skinny beaks work in only large spaces, fat beaks can only fit in narrow spaces",
"skinny beaks work to reach small spaces, fat beaks crack nuts",
"skinny beaks work to filet fish, fat beaks are useless"
] | C | a skinny beak is used for obtaining food by a bird from small spaces |
OpenBookQA | OpenBookQA-2472 | electromagnetism
Title: Region of most and least intense magnetic field
It's a unmagnetized iron screw placed in the north pole of a U shaped magnet. I believe the region of least intense magnetic field is at the far left of the board. From what I understand the screw becomes magnetized and it's south pole is where it's touching the north of the magnetic, is it correct to assume the most intense magnetic field will be where the screw is touching the magnet due to there being direct contact between them?
Consider these images showing the magnetic field lines of a horse-shoe magnet. Magnetic intensity at any point in its field is directly proportional to its magnetic flux.So the region where the field lines are more densely packed have a higher intensity than where the field lines are loosely packed. If possible, draw the field lines for your own case and you will realize where the magnetic intensity is most and least.
The following is multiple choice question (with options) to answer.
Which would be most affected by a magnet? | [
"a wooden beam",
"a titanium beam",
"a plastic beam",
"a cotton beam"
] | B | if a magnet is attracted to a metal then that magnet will stick to that metal |
OpenBookQA | OpenBookQA-2473 | ornithology
Title: How do birds learn their tunes in isolation from their own species? I wonder what a bird would sing if it didn't have its parents around (or any other birds for that matter) to learn its chirping sounds from.
I'm interested in how a bird would sing...
in complete isolation from creatures communicating through sound;
in isolation from its own species, but with other birds;
in isolation from all birds (other animals and creatures are there for it)
For example,
Would a bird even feel the need to speak up if there wasn't any other vocalizing creature around?
Would a bird learn other species' signals? Would it only learn from one species, the one which it would think of a fitting mate?
Would a bird try to mimic a non-flying creature's signals?
These are similar questions, but if you think they should be separated, let me know in the comments. Birds have to learn their song patterns.
They are able to chirp, but the songs with "meaning" are learned from their parents or whatever they learned to be their "parent".
Here is a paper that related bird song learning to human learning (of speech, for example).
Birds brought up by parents from another species learned to sing their songs.
There are many birds that learn to imitate other animals or sounds, so in isolation from all birds they will probably do this.
I can't recall where, but I read a paper once, where little finches brought up by humans developed a song resembling the "Hello there, now there's food", their caretaker always greeted them with. (Not the speech, but the overall sound pattern.) They might not understand the signals, but they try to communicate nevertheless. Some birds use sound from other species to mock others, scare them off or lure them into thinking they might be more powerful than they are.
Birds brought up in total isolation do sing, but not the typical songs you know from their species. Deaf birds who can't hear themselves, though, do not (always) sing.
The following is multiple choice question (with options) to answer.
Sometimes birds | [
"dance to attract predators",
"hide seeds from other birds by burying them",
"hide seeds in hollow trees to eat during the winter",
"cause the spread of plants by pooping hard objects found in fruit"
] | D | birds are a vehicle for spreading the seeds of a plant |
OpenBookQA | OpenBookQA-2474 | homework-and-exercises, kinematics
In order to conclude that the runner with the shorter time was indeed faster...
and am wondering whether this ought to be interpreted as a statistical hypothesis test. If you say that the null hypothesis is "they are going at the same speed, the tracks are different length" and the alternate hypothesis is "the track length alone cannot explain the difference in time", then you need to make a decision about the confidence level with which you reject the null hypothesis. So you need to ask yourself -
For a given velocities $v_1, v_2$ with error $\Delta v$, what is the track length difference for which $v_1 > v_2$ with > 95% confidence
That means we are looking at the error in velocity (which I estimated above at 0.07%) and choose the track lengths $T_1, T_2$ such that the velocity calculated from the times is different. This is a slightly different calculation than I had above, but it argues for rounding up the answer, rather than claiming that the mean difference is exact. To go from 50% to 95% confidence you need mean + 1.28 $\sigma$ (one sided confidence interval).
The following is multiple choice question (with options) to answer.
How would a runner measure speed? | [
"breaths taken",
"water drank",
"seconds passed",
"people passed"
] | C | seconds are used to measure time |
OpenBookQA | OpenBookQA-2475 | quantum-mechanics, operators, measurement-problem, eigenvalue, observables
If you measure the length of a piece of paper with a ruler for example, you will not obtain a different result when you measure it again.
When you now measure a quantum system, you have two types of statistics in there. First, your particle exhibits certain probabilities to be at a certain location. Secondly, your measurement apparatus is never 100% precise. The best you can do is perform lots of different measurements of identically prepared systems which is also a source of uncertainty because identical preparation might be difficult in real life. You will obtain the probability of presence of the particle at a certain position. But since the position is a continuous variable, there will always be an error. You can never measure "true values" but you will not be "limited by the collapsed state" as you formulated it.
The following is multiple choice question (with options) to answer.
A person wants to use a ruler to measure something so they measure | [
"an ounce of water",
"the volume of a room",
"a liter of gas",
"an old broken phone"
] | D | a ruler is used for measuring the length of an object |
OpenBookQA | OpenBookQA-2476 | thermodynamics, thermal-radiation
Title: Why don't gas flames radiate much heat directly, but metal objects heated by them do? Gas barbeque manufacturers place metal bars, ceramic plates or lava rocks above the gas burner so that they radiate more heat towards the grill. Cooking directly over a single gas flame just wouldn't work very well.
Why don't gas flames radiate much heat directly but a metal/ceramic object heated by the same flame does? For example, you can put your hand near a flame and not feel anything but lava rocks will scorch your skin easily. The luminous flame itself is hot; the site where the chemical process of combustion takes place. But the product of combustion, typically CO₂, H₂O, and perhaps some CO gas carry off a great quantity of the heat energy created in the reaction.
The main purpose of the lava rocks, grill etc. is to capture a good part of that heat flux so it doesn't just blow by the food into the atmosphere. Another reason is to provide a more uniform distribution over the cooking field.
The reason the lava rocks 'feel' hotter than the bare flame is that they have the capacity to store a lot of that heat. The flame and hot product gases transfer heat over time and that heat integrates over time to raise the temperature of the rocks.
The following is multiple choice question (with options) to answer.
A person needing to cook up a burger, but lacking a grill or fire, can heat burger meat on | [
"a tree branch",
"a puddle",
"a fish pond",
"a vehicle engine"
] | D | a car engine is a source of heat |
OpenBookQA | OpenBookQA-2477 | blood-circulation
Title: Why don't we bleed interstitial fluid? Interstitial fluid is the fluid between cells in tissues - forming the medium between cells and capillaries. From what I gather, the typical human has 5L of blood and 11L of interstitial fluid. This raises an interesting question. If I get cut, why do I not bleed interstitial fluid?
When humans are cut, generally their capillaries open and blood comes out. But this should also allow the interstitial fluid to come out - so why don't we see it? For fluid to flow from a wound there needs to be a significant pressure gradient between where it is now and the outside of the body. Your skin generally does not have a strong compressive effect, which is why a deep cut exposing fat will not lead to the fatty tissue being expulsed from the body any more than the interstitial fluid is.
Blood, however, flows. For it to circulate there needs to be a pressure gradient between where it is now and where it is going. Since veins (including the vena cava, which channels blood back into the heart) do not have vascular walls strong enough to create a suction effect (i.e. lower pressure than the surrounding tissue), you can conclude that the pressure of blood vessels is always higher than that of surrounding tissues, and thus higher than the pressure outside of your body. This is why all blood vessels, including veins, will bleed, whereas less pressurized systems such as interstitial fluid will not.
The following is multiple choice question (with options) to answer.
Blood gets directed around beneath skin and bone by | [
"a person",
"a vision",
"a thought process",
"long passages"
] | D | the circulatory system transports blood throughout the body |
OpenBookQA | OpenBookQA-2478 | ecology, population-dynamics, ecosystem, antipredator-adaptation, predation
I would also like to talk about other things that might be of interest in your model (two of them need you to allow evolutionary processes in your model):
1) lineage selection: predators that eat too much end up disappearing because they caused their preys to get extinct. This hypothesis has nothing to do with some kind of auto-regulation for the good of species. Of course you'd need several species of predators and preys in your model. This kind of hypothesis are usually considered as very unlikely to have any explanatory power.
2) Life-dinner principle. While the wolf runs for its dinner, the rabbit runs for its life. Therefore, there is higher selection pressure on the rabbits which yield the rabbits to run in average slightly faster than wolves. This evolutionary process protects the rabbits from extinction.
3) You may consider..
more than one species of preys or predators
environmental heterogeneity
partial overlapping of distribution ranges between predators and preys
When one species is absent, the model behave just like an exponential model. You might want to make a model of logistic growth for each species by including $K_x$ and $K_y$ the carrying capacity for each species.
Adding a predator (or parasite) to the predator species of interest
... and you might get very different results.
The following is multiple choice question (with options) to answer.
If many birds in the area are killed the ecosystem may become overcrowded with | [
"chickens",
"insects",
"cats",
"birds"
] | B | if the population of an organism increases then the ecosystem may become overpopulated with that organism |
OpenBookQA | OpenBookQA-2479 | classical-mechanics
Surface of the earth
Again we work in the non-rotating reference frame. We have again, via the constant density assumption, (and assuming that the mass of stone is 1) that the potential energy is $P = \alpha r^2$. The kinetic energy is $2K = \dot{r}^2 + r^2\dot{\theta}^2 + (r\cos\theta)^2\dot{\phi}^2$. The conservation of angular momentum means that angular component of the velocity is of size $L / r$, where $L$ can be computed from the rate of rotation of the Earth. So the conserved energy is
$$ E = \dot{r}^2 + \frac{L^2}{r^2} + \alpha r^2 $$
This gives an ODE for $r$. Similarly using a tilted coordinate system you can solve for the angles using the conservation of angular momentum by integrating an ODE and plugging in the solution for $r$.
For the maximum depth, however, you don't need to explicitly solve the ODE: The energy is known initially: $E_0 = 0+ \frac{L^2}{r_0^2} + \alpha r_0^2$, where $L$ depends only on the rate of revolution for Earth, and $\alpha$ on the mass of Earth (assuming uniform density). $r_0$ is the radius of Earth. At the maximum depth, $\dot{r}$ is again 0. So you are down to finding the "other" positive root of the quartic polynomial
$$ E_0 r^2 = L^2 + \alpha r^4 $$
which you can solve explicitly using the quadratic formula
$$ r^2 = \frac{E_0 \pm \sqrt{ E_0^2 - 4 \alpha L^2}}{2\alpha } $$
where the + solution is the radius of the earth, and the - solution is the depth.
The following is multiple choice question (with options) to answer.
A wet globe that is enormous in mass is likely to have a stone | [
"layer",
"sun",
"brain",
"labyrinth"
] | A | Earth 's surface is made of rock |
OpenBookQA | OpenBookQA-2480 | ecology, behaviour, sociality, predation, community-ecology
Title: How selective are wolves about the size of their prey? For an animal that lives and hunts socially like a wolf, is there a lower threshold to the size of prey items they will hunt? A pack wouldn't have much trouble with catching say a rabbit, but would the food provided be enough to actually make the hunt worthwhile? What is the limit in which a prey item becomes too small to be worth catching? You should not post here until you've demonstrated your own research effort. Given this stipulation -- and the rich literature about this very topic -- I will keep my answer cursory so as to act as starting points for your search. A simple Google or google Scholar search on your part will reveal many more details/studies.
You should review the following ecological concepts: prey switching, optimal foraging theory, principle of allocation, and others.
Some accessible articles on Prey-to-predator-size ratio include: Henriques et al. 2021, Tsai et al 2016, Cohen et al 1993, and Vézina 1985
Regarding wolves:
According to Becker et al 2018:
[Wolf] Prey selection is influenced by the absolute and relative abundances of prey types, the life history characteristics of predators and prey, and the attributes of the environment in which these interactions occur.
Smith et al. 2010 demonstrate that diets vary with season -- their focus being on winter diets.
Huggard 1993 shows the impact of environmental variables such as snow.
Herd density plays a significant role:
Sand et al. 2016
Davis et al 2012 showed that lower density of secondary prey mattered more than heightened density of primary prey.
Huggard 1993 (Canadian Journal of Zoology) showed that density of herds (vs herd density) mattered more in Banff National Park in Canada. Herd size and habitat also mattered -- with wolves avoiding some habitats and seemingly choosing places that optimized preferred habitats and large herd size.
Wolf scat/diet studies showing smallest species in their diet:
Sin et al 2019: smallest for Sandanavian wolves = domestic dogs
Nowak et al 2011 showed the following small prey made up the stated percentages of wolve's diets in Poland:
brown hare Lepus europeus (2.5%) and Eurasian beaver Castor fiber (1.4%). Domestic animals, exclusively dogs and cats, made up 1.0% of food biomass.
Works cited:
The following is multiple choice question (with options) to answer.
Where would an arctic hare be least likely to be seen by a predator? | [
"sitting on the dirt",
"on a sand dune",
"on a grass lawn",
"on a hill covered in deep, white, cold stuff"
] | D | An example of camouflage is when something changes color in order to have the same color as its environment |
OpenBookQA | OpenBookQA-2481 | navigation, mapping, turtlebot
Originally posted by tfoote with karma: 58457 on 2017-10-09
This answer was ACCEPTED on the original site
Post score: 1
Original comments
Comment by Baumboon on 2017-10-11:
Okay , then i need to improve the navigation stack and optimize it. Thank u for your help.
The following is multiple choice question (with options) to answer.
A navigator may be in charge of | [
"shoveling a sidewalk",
"clearing a tree",
"conducting a car",
"riding a bike"
] | C | An example of navigation is directing a boat |
OpenBookQA | OpenBookQA-2482 | ecology, behaviour, sociality, predation, community-ecology
Title: How selective are wolves about the size of their prey? For an animal that lives and hunts socially like a wolf, is there a lower threshold to the size of prey items they will hunt? A pack wouldn't have much trouble with catching say a rabbit, but would the food provided be enough to actually make the hunt worthwhile? What is the limit in which a prey item becomes too small to be worth catching? You should not post here until you've demonstrated your own research effort. Given this stipulation -- and the rich literature about this very topic -- I will keep my answer cursory so as to act as starting points for your search. A simple Google or google Scholar search on your part will reveal many more details/studies.
You should review the following ecological concepts: prey switching, optimal foraging theory, principle of allocation, and others.
Some accessible articles on Prey-to-predator-size ratio include: Henriques et al. 2021, Tsai et al 2016, Cohen et al 1993, and Vézina 1985
Regarding wolves:
According to Becker et al 2018:
[Wolf] Prey selection is influenced by the absolute and relative abundances of prey types, the life history characteristics of predators and prey, and the attributes of the environment in which these interactions occur.
Smith et al. 2010 demonstrate that diets vary with season -- their focus being on winter diets.
Huggard 1993 shows the impact of environmental variables such as snow.
Herd density plays a significant role:
Sand et al. 2016
Davis et al 2012 showed that lower density of secondary prey mattered more than heightened density of primary prey.
Huggard 1993 (Canadian Journal of Zoology) showed that density of herds (vs herd density) mattered more in Banff National Park in Canada. Herd size and habitat also mattered -- with wolves avoiding some habitats and seemingly choosing places that optimized preferred habitats and large herd size.
Wolf scat/diet studies showing smallest species in their diet:
Sin et al 2019: smallest for Sandanavian wolves = domestic dogs
Nowak et al 2011 showed the following small prey made up the stated percentages of wolve's diets in Poland:
brown hare Lepus europeus (2.5%) and Eurasian beaver Castor fiber (1.4%). Domestic animals, exclusively dogs and cats, made up 1.0% of food biomass.
Works cited:
The following is multiple choice question (with options) to answer.
Losing which of these would make it hard for a wolf to satisfy hunger? | [
"tail",
"eyebrow",
"eyelash",
"snout"
] | D | smell is used for finding food by some animals |
OpenBookQA | OpenBookQA-2483 | • $P_2$ will fly $\big[1-(d+r+y)\big]$ distance away from the airport in the counter-clockwise direction to meet up with $P_3$.
• At this point, $P_2$ will donate $z$ fuel to $P_3$.
• $P_2$ and $P_3$ will then both fly back $z$ distance, arriving at a distance of $1-d-r-y-z$ from the airport with no fuel.
• After refuelling at the airport, $P_1$ will fly the distance towards $P_2$ and $P_3$ and refund each of them for that much fuel. All three planes will then head back to the airport together.
From this, we must have
• $0 \leqslant s\leqslant d/3$: $P_1$ can fly $s$ distance forward and backwards, and refund $P_2$ for $s$ distance
• $z\geqslant 0$: cannot donate negative fuel
• $2x + 1-d-r-y \leqslant d+r+y$: $P_3$ must not run out of fuel before $P_2$ can reach it again
• $1-d-r-y - z \leqslant d/4$: $P_1$ can reach $P_2$ and $P_3$, refund them both, and the three of them will have enough fuel to head back to the airport
• $2x + 2s + 1-d-r-y - z\leqslant d+r+y + z$: $P_2$ and $P_3$ must not run out of fuel before $P_1$ can reach them again
Putting these together:
The following is multiple choice question (with options) to answer.
A person wanting to pay airfare will ride | [
"through clouds",
"on seas",
"across rails",
"on tracks"
] | A | a plane travels through the atmosphere |
OpenBookQA | OpenBookQA-2484 | It just turns out nicely for C that he is one of the people whose hat colors D and C both know about.
To introduce a modified challange: if the task were to yell out C's hat color right away, D would know for certain, C would have the increased probability of $2/3$ and A and B would be stuck with the random guess of $1/2$. D still knows more.
The following is multiple choice question (with options) to answer.
An action that may provide a small bit of warmth could be | [
"looking out of a window",
"putting the radio on",
"looking at a snow storm",
"smashing hands together repeatedly"
] | D | friction occurs when two object 's surfaces move against each other |
OpenBookQA | OpenBookQA-2485 | pain, death
Title: Normal death experience Consider a natural cause of death (no car accidents etc) -
Is it true that death is generally preceded by suffering? In other words, are we destined to experience the most severe suffering we could not ever imagine, that will ultimately end with death?
If this is true, is it true for all living things? No and no.
I'm not sure what is a "natural cause" in this context, but if it's cardiac arrest caused by age-related dystrophy of the cardiac muscles, then no, there is no suffering, at least not universally: Since age-related dystrophy hits all parts of the body, it's likely preceded by increasing amounts of bed rest, leading to quietly drifting off into the great sleep.
Of course, if you add on other natural causes like age-related diseases or being eaten by predators, the suffering can be great indeed, or not: A tiger will sneak up on you and crush your skull without you ever knowing what happened.
Adding on further causes still, like dehydration or hunger, and the suffering is back.
But is suffering a universal fixture of death? Emphatically no.
As for the "all living things" part of the question, the answer isn't just "no"; it's "that's nonsensical".
By individual count, practically no life is complex enough for suffering to be a relevant concept.
I don't have an exact number for you, because how would I get one, but at a rough estimate, bacteria, algae and archea constitute 100% of all individual life forms by count, and suffering is not a concept that makes sense for them.
If we ignore simple life, even among complex life there is so much variety of capabilities that basically nothing universal exists.
The following is multiple choice question (with options) to answer.
Which of the following would be considered nonliving? | [
"a hair still on your head",
"a rabbit hopping along",
"a fallen palm leaf",
"a human jogging down a track"
] | C | if a leaf falls off of a tree then that leaf is dead |
OpenBookQA | OpenBookQA-2486 | botany, plant-physiology, plant-anatomy
It made me wonder if we are simulating the sun in a dark room for growing the plants with the help of red, blue, and a little bit of far-red light, what will happen to the plants if we keep the ideal conditions for which the plants carry out photosynthesis whole day? Does it affect its yield or the plants die out quick?
I am an engineering student working on indoor farming, my knowledge of botany is the same as a high school student. So if I am wrong please tell me. Ideal conditions for photosynthesis
You mention ideal conditions to carry out photosynthesis, I would just like to point out that this includes carbondioxide levels, temperature, and nutrients as well as light.
Flowering
As anongoodnurse mentions performance might be measured by blooming which, in most flowering plants, has a day-light related component. However, for general growth increasing daylight over the 'natural' day length can often increase yield.
Daylight Cycles
The important point to note is that plants do 'ramp up' at dawn getting ready to start photosynthesizing (for some plants with temporal photosynthesis mechanisms (see CAM photosynthesis) this can be even more important). The reason plants do this is because plants can suffer from 'photobleaching' which can be considered similar to sunburn in humans, if they are not ready for sunlight. Getting 'ready' can involve lots of things including opening stomata (pores) to let CO2 in, changing which metabolic pathways are active, and moving about chloroplasts inside cells. Plants 'figure out' how and when to ramp up based on circadian rhythms which work well on 24 hour clocks and slight changes over time. Thus 12 hrs to 16 hrs can be a big change, particularly if the change happens by lights coming on earlier. Additionally, the 24 hour 'clock' means that plants will do better with 18hr light then 6hrs dark cycles than 36hrs light 6 hrs dark, because the total cycle length should be about 24hrs.
Photosynthesis Side Effects
The following is multiple choice question (with options) to answer.
Which most directly requires sunlight to grow? | [
"a rock",
"a cat",
"a bamboo stalk",
"a bird"
] | C | a plant requires sunlight to grow |
OpenBookQA | OpenBookQA-2487 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
Where various seasons currently take place depends upon | [
"the globe's size",
"the world's view",
"the earth's consideration",
"the globe's turning"
] | D | winter in the Northern Hemisphere is during the summer in the Southern Hemisphere |
OpenBookQA | OpenBookQA-2488 | thermodynamics, optics, temperature, air
Title: Vibrating hot air around heater The other day I was in a restaurant and I saw one of those patio heaters that looks like lamps turned on. The air around it appeared to be vibrating. Why does this happen from the optics point of view? (couldn't find a good picture of this) When air is heated up, but the pressure is constant, the density will decrease (in accordance with the ideal gas law).
Now we usually think of air as having a refractive index of 1.0 - same as vacuum. In fact, the value of the refractive index for dry air at STP is around 1.000277 (at 600 nm).
When you increase the temperature, the refractive index will drop. This in turn means that light that travels through a region that is hotter in some parts and cooler (denser) in other parts will experience a small amount of deflection - whenever the thermal gradient is not parallel to the line of sight.
The normal visual acuity is around 1 minute of arc - that is 1/60th of a degree. This means that light needs to bend just a tiny bit for the eye to notice the deflection. And it turns out that the turbulent flow of hot air contains plenty of refractive index changes.
I believe this is the kind of picture you have in mind (part of a picture of an Airbus 319
It shows that the picture behind the jet engine exhaust is distorted.
The following is multiple choice question (with options) to answer.
What will air usually do when heated up beyond a certain point? | [
"it will fall",
"it will remain",
"it will ascend",
"it will die"
] | C | if gas is heated then that gas will rise |
OpenBookQA | OpenBookQA-2489 | proteins, muscles, amino-acids, protein-binding
It is possible for people on unusual protein diets, either because they are avoiding animal products or using incomplete protein supplements, to develop a particular amino acid deficiency. Otherwise, as long as all amino acids are supplied, there is no difference on health or muscles to consuming "low quality" vs "high quality" proteins.
The following is multiple choice question (with options) to answer.
With proper nutrition, which activity would increase the body's strength? | [
"breathing",
"weighted dips",
"sleeping",
"eating"
] | B | exercise has a positive impact on a body 's strength |
OpenBookQA | OpenBookQA-2490 | 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.
A person needing to last a long time in an arid space with limited water sources will | [
"drink sparingly",
"drink frequently",
"drink greedily",
"drink liberally"
] | A | conserving water can be used for survival in a dry environment |
OpenBookQA | OpenBookQA-2491 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
When soil is disrupted to extreme levels | [
"plants thrive",
"environments suffer",
"mice breed",
"bugs hoard"
] | B | erosion of soil has a negative impact on the environment |
OpenBookQA | OpenBookQA-2492 | material-science, elasticity, continuum-mechanics, stress-strain
In short, once you properly glue the bottom of the cube to the floor, you can expect something more similar to what visible here
rather than in the picture above.
It is just funny that sketches like the one above are so widely used to explain shear stress. I think it is kind of risky and can lead to inconsistencies and (legitimate) doubts in students, I wonder how many persons are aware.
I have to say that some texts indicate the presence of vertical external forces also on those two lateral surfaces (then it all works and the uniform deformation above is correct)... but more often this is neglected.
The following is multiple choice question (with options) to answer.
An area of dirt may have rivets in it depending on | [
"if soil is piled up",
"if there is more soil",
"if soil has been altered",
"if soil has been added"
] | C | soil loss causes grooves in soil |
OpenBookQA | OpenBookQA-2493 | particle-physics
Title: Explanation for self-rupture glass is needed I witnessed a phenomenon that I couldn't conclude its cause. Please bear with me for the length of the recall, for I merely want to include any details that might help us to investigate. I had a cooking glass lid sat on a wooden shelf that is away from the stove and oven and other heating objects. The shelf is nailed on the wall and is situated just above my eye level, and a counter top is also on the same side of the wall where the shelf is installed.
Now here comes the surprise. In a winter afternoon 2011, my room had almost the same temperature as an autumn morning, and while I was cutting my lettuce on that counter top which I pointed out in above passage, a pounding sound, as if a heavy car door slam or a tree trump falling on top of the roof, knocked its introduction from the shelf that was just above my eye level. First, I thought I may had knocked something around me off(which I didn't believe that for there wasn't anything around me to knock off); then I thought it may be my neighbor next door dropping a heavy box; last, I suspected somewhere my roof top collapsed.
But it was my third suspicion directed me to meet that glass lid I mentioned above, and I found it had ruptured completely like glacier creaked BUT still having all broken pieces bounded without any pieces scattering toward random direction! Only the nob of the lid popped out partially. Before this happened, I hadn't used that lid for cooking for years, and I didn't removed it from any heating object nor there was something on top of the lid that day, and I believe what the lid had maybe just an invisible layer of dust.
I was glad my face hadn't been stung by any glass residues, but ponder what really happen to that glass lid and why it ruptured without collapsed. Below, I attached 2 pictures of the scene from that day. If you have any similar experience or know the theory behind it, may you please drop me an explanation to this incidence? Thank you in advance.
The following is multiple choice question (with options) to answer.
A boy has a scar from an oven on his leg, so his leg was likely | [
"snagged",
"seared",
"removed",
"frozen"
] | B | if a body part was burned then that body part was exposed to a lot of heat energy |
OpenBookQA | OpenBookQA-2494 | thermodynamics, everyday-chemistry, water, heat, vapor-pressure
in unknown amounts.
The gauge pressure is given as $p_\mathrm e = 0.8\ \mathrm{bar}$; i.e. the absolute pressure is approximately $p = 1.8\ \mathrm{bar}$.
We may use so-called steam tables to look up the properties of water at the given pressure (in the following, I use parameter values taken from the REFPROP – NIST Standard Reference Database 23, Version 9.0). We may find that the saturation point (equilibrium of liquid water and steam) at a pressure of $p = 1.8\ \mathrm{bar}$ corresponds to a temperature of $T = 117\ \mathrm{^\circ C}$.
At this point, the density of liquid water is $\rho_\mathrm l = 946\ \mathrm{g/l}$ and the density of steam is $\rho_\text{steam} = 1.02\ \mathrm{g/l}$.
If we ignore the volume of the remaining liquid water, air, and food, we may consider the limiting case in which the entire volume $V$ is filled with steam. Thus, the mass $m_\text{steam}$ is given by
$$\begin{align}
m_\text{steam} &= \rho_\text{steam} \cdot V \\[3pt]
&= 1.02\ \mathrm{\frac gl} \times 6.2\ \mathrm l \\[3pt]
&= 6.3\ \mathrm g
\end{align}$$
Therefore, only $6.3\ \mathrm g$ of water (which corresponds to about $6.3\ \mathrm{ml}$ of cold water at normal pressure) are required to fill the entire volume with steam at the given pressure.
The following is multiple choice question (with options) to answer.
A person is wondering how much the steam from the pot of water that is boiling will measure. They are able to measure it in a definite way by | [
"making the liquid condense outdoors",
"remembering how big steam clouds are",
"burning the hot steam",
"collecting the condensed liquid"
] | D | Matter in the liquid phase has definite volume |
OpenBookQA | OpenBookQA-2495 | analytical-chemistry, solutions, extraction
To tschoppi (since I don't have enough reputation to comment) : I haven't tried with another kind of foam, but it's a good idea (to see at which step the problem lies). I'll see what we have in the lab. I am also pretty sure the foam I used isn't contaminated, because it was given to us straight from the package, and I washed it three times with different solvents and analysed the wash-solvent (which was clean)(but I may check again to be sure). I found the answer to my question, and I am going to share it just in case.
Apparently, when extracting the pollutants from the foam, I am also extracting some foam-specific materials that influence the pollutants' behaviour during the SPME part of the extraction.
I tested that by extracting the blank foam, then adding a standard amount of pollutants to the extraction solvent. This gave the same result as extracting a spiked foam, meaning higher peak areas than a standard solution.
In short : matrix effect from the foam. I don't yet know why or what, but it's a matrix effect.
The following is multiple choice question (with options) to answer.
Which of these could add unwanted contamination to the natural environment? | [
"making compost",
"hoarding trash",
"eating fruit",
"burning liquid petroleum"
] | D | burning oil is a source of pollution |
OpenBookQA | OpenBookQA-2496 | biochemistry, botany, plant-physiology, photosynthesis, agriculture
The above image is an example of a "potato battery" made without the potato. Identical setup and the energy obtained is identical given everything else the same.
Potato power- er, metal power?
This experiment is supposed to demonstrate the concept of an electrochemical cell. Electrochemical cells obtain their energy from the reduction-oxidation reactions that happen between two metals with different reduction potentials. When two metals - such as copper and zinc - are placed in a medium that permits the exchange of electrons and ions, an electrical gradient is produced as electrons move from one metal to the other and ions move the other direction. This gradient can then be captured and used to do work such as powering a lightbulb or an AI.
In the potato powered example, the power comes from zinc and copper. If you want a more powerful battery, use more zinc and more copper- not a bigger potato. If that is not good enough, try replacing the zinc with something like lithium- this is what we've done with modern, rechargeable batteries.
In truth, the potato battery would be better described as a normal battery that just happens to be inserted into a potato. You'll make a better battery if you use copper pennies and aluminum foil in vinegar.
I do not mean to shoot down your idea, and I am glad you are looking into renewable energy sources- but you may be better served by a class on electricity and batteries than by asking questions on biology.SE!
EDIT: I would assume that the electrical potential of this kind would also kill the plant, given that you're essentially electrocuting it. However, I was unable to find any information on the resistance of potato plants to electrocution.
The following is multiple choice question (with options) to answer.
A person wants to use a chemical energy to power a radio, so they change out the energy source through | [
"water",
"AAs",
"wind",
"the sun"
] | B | batteries convert chemical energy to electrical energy |
OpenBookQA | OpenBookQA-2497 | classical-mechanics, energy, electricity
Title: Can we imagine having a computer keyboard that recharges itself through mechanical utilization? Silly question here.
I have a debate with my father, and while I am decent at high school level physics, both he and I cannot determinate through calculus which of us is wrong.
Basically, he had the idea that perhaps, through simple mechanical utilization, a wireless keyboard can be charged and used, without any other energy source. (The keyboard can have a battery that can be recharged through the said mechanical utilization though), I have the intuition that the idea is interesting, but physically problematic.
With simple research, I have seen that an idle keyboard has a consumption of $1W$, and a used keyboard will use between $1.5$ and $2.5W$.
So, we have specific questions:
Is collecting the mechanical energy from the keyboard doable ?
And if yes, how much energy can typing on a keyboard's key produce ?
How it may impact the overall comfort of the user ?
I have multiple difficulties to answer these myself. How can I know how much a person can generate through typing, how much energy will be lost in the process of using a battery, etc..?
(This is not a concept that I try to sell or anything, this is a mere thought experiment that I wanted to share and resolve, please do not take it too seriously) What you are looking for is fairly simple. All you need to do is build a piezoelectric generator under each key. These generate electricity with each push. With this the element is stretched or vibrated with each push and this generates electricity. Do a Google search and you will find much more.
The following is multiple choice question (with options) to answer.
Which uses electrical energy to function? | [
"liver",
"tree",
"dog",
"iPod"
] | D | electric devices require electrical energy to function |
OpenBookQA | OpenBookQA-2498 | newtonian-mechanics, newtonian-gravity, statics, stability
Title: Why can't a pyramid stay balanced on a vertex? A pyramid, such as a tetrahedron/3-simplex, or any other isohedron, falls from some height and lands on a vertex. It will eventually end up with a face to the ground.
Why can't it stay balanced on a vertex?
EDIT: this is not the same question as Can we theoretically balance a perfectly symmetrical pencil on its one-atom tip? because there symmetry is assumed. For this question I am not making any assumptions about symmetry. Also, in my situation the object is falling from a height. The issue there is assuming it starts on the ground. In terms of Newtonian mechanics, the state of a rigid body, which uniquely determines the time evolution, is fully described by the position $\mathbb R^3$ and orientation, an element of $SO(3)$, linear momentum, an element of $\mathbb R^3$, and angular momentum, an element of $\mathfrak{so}(3)$, the Lie algebra of infinitesimal rotations. This is a 12-dimensional space.
Let's consider a state at the moment the tetrahedron is released in which it ends up balanced on one of its vertices. It is clear that there is not a 12-dimensional neighborhood of states that also end up on a vertex: translations would not change it, small changes in initial orientation would most probably make it fall, a change in the direction of the linear momentum would keep it ending up on its vertex, but a change in it's magnitude probably not (you would have to specify the problem more precisely, like in the initial orientation), and finally a small change in angular momentum would most of the time, at least in two of the dimensions, make it fall as well.
What this shows is that the space of initial conditions is probably 5-dimensional or so. It might have some components of higher dimension depending on the problem's specifics, but always strictly lower dimensional than the full space of initial conditions. So whatever continuous probably distribution you put on that space, it will have measure (hence probability) 0.
The following is multiple choice question (with options) to answer.
Jane's hat flew off her head while standing still on a hilltop. This could be because | [
"her head blew the hat off",
"there was uneven heating of the ground",
"a squirrel jumped up and grabbed it off of her head",
"a spaceship pulled her hat off her head"
] | B | uneven heating of the Earth 's surface cause wind |
OpenBookQA | OpenBookQA-2499 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
migration is when animals travel from the northern most state to Texas during what segment of time? | [
"lake fronts",
"birds",
"winter",
"spring"
] | C | migration is when animals move to different locations in an annual cycle |
OpenBookQA | OpenBookQA-2500 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Which would create the most pollution | [
"animals",
"rivers",
"smoke stacks",
"toxicity"
] | C | polluting means something poisonous is added to an environment causing harm to the environment |
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