source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-1801 | inorganic-chemistry, alloy
Title: If alloys are homogeneous mixtures, why can't we separate their components? An alloy is a material composed of two or more metals or a metal and a nonmetal. And, they are usually formed by heating the elements to their melting points, and then cooling them, so that the components mix. Now, why doesn't this works backwards i.e. if we heat the alloy again to melting point of their constituents, and they should separate? Once the alloy has been formed the atoms from the different metals will have shared there electrons with each other and come to an equilibrium. In this state the metal atoms have formed a complex structure which has a different reactivity or properties than each individual metal did in its original form .
The following is multiple choice question (with options) to answer.
Alloies are made of multiple metals an example is | [
"brass",
"steel",
"aluminum",
"tin"
] | A | brass is made of copper and zinc |
OpenBookQA | OpenBookQA-1802 | waves, atmospheric-science, turbulence
The clouds form if the rising air reaches the lifted condensation level before the updrafts are stopped by an inversion or stable layer. The air is (relatively) clear above the downdrafts. If the convection rolls were perfectly circular, the cloud row spacing would be twice the height of the inversion/stable layer.
Mathematically, there are many wavelength solutions to convection, but the wavelength that dominates is the fastest growing one. In the Boussinesq approximation, which is reasonably valid here, this turns out to have a wavelength of $2\sqrt{2}\sim 3$ times the height of the convecting layer, i.e. slightly flattened. (See, for example, Eq. 21 of Kuettner (1971) "Cloud bands in the earth's atmosphere: Observations and Theory".)
For typical cumulus cloud heights of $\sim 2$ km, we expect typical spacings of about $6$ km.
Wave, lee, or mountain clouds are lines of clouds downwind of an obstacle (such as a mountain range). The lines are parallel to the wind direction. These are buoyancy waves where wind pushes denser air over an obstacle (e.g. a mountain range) and it ends up above less dense air on the other side. This dense air starts to fall but it overshoots into even higher density air at lower altitude, which forces it back up, and the air ends up bouncing up and down until the oscillations die out. If the vertical temperature profile of the air then is known, it is possible to estimate the vertical buoyancy angular frequency
$$N=\sqrt{\frac{g}{\theta}\frac{d\theta}{dz}}$$
The following is multiple choice question (with options) to answer.
A cloud gets fat and heavy because | [
"precipitation destroys",
"clouds float",
"precipitation condenses",
"precipitation falls"
] | C | condensation is a stage in the water cycle process |
OpenBookQA | OpenBookQA-1803 | zoology, ornithology, ethology, behaviour
Title: Crow branch pecking behaviour I was walking through a small park when two crows started cawing at me, and followed me, flying from tree-to-tree as I walked. I speculate that this is a territorial or protective behaviour, but what I found different was the crows were violently pecking the branches nearby them. I have no memories coming to mind of seeing this behaviour beforehand. I speculate that this behaviour could be threat displays, but a quick search on Google did not reveal to me any authoritative studies on this phenomenon. I'd appreciate more information and sources.
This question has been added as a casual observation on iNaturalist. This is a good question. This type of behavior -- pecking at a branch, wiping the side of the beak on a branch, pulling off twigs and dropping them, or knocking off pieces of bark -- is quite common among many corvid species, particularly when they are interrupted by something or someone that they might consider a threat. This includes not only potential predators but also potentially hostile conspecifics.
It is typically considered to be a form of displacement behavior. The concept of displacement behavior, from classical ethology, posits that when an animal experiences two conflicting drives to do two different things, it doesn't know which to do and does a third thing instead to dissipate the drive or anxiety. For branch-pecking in crows, see E.g Kilham and Waltermire 1990 Ch. 12.
Referece: Kilham, L., & Waltermire, J. (1990). The American crow and the common raven. Texas A&M University Press.
The following is multiple choice question (with options) to answer.
Some birds use their beaks for the same purpose as their | [
"eggs",
"feathers",
"feet",
"wings"
] | C | sharp beaks are a kind of adaptation for catching prey |
OpenBookQA | OpenBookQA-1804 | taxonomy
Title: Why are sponges sometimes not considered multicellular? I read somewhere (I can't find where) that there is no scientific consensus whether sponges should be considered multicellular organisms.
It seems I don't understand where is the line between unicellular and multicellular life.
I am not able to find a more elaborate explanation of that doubt. What are the reasons for it? Sponges are generally considered as colonial organisms because there is little cell specialization and little separation of function/role. All cells do pretty much the same thing; it looks more like a pile of individual cells than an actual multicellular organism. In reality it is a little bit in between.
In any case, what one wants to call multicellular or unicellular is a matter of definition and preferences. You cannot find the line between unicellular and multicellular because there is no such line that would not be very arbitrary and filled with special cases.
You can study a little more the physiology of sponges and then decide for yourself if it looks sufficiently like a multicellular organism or more like a colony of cells (a colonial organism).
The following is multiple choice question (with options) to answer.
Where would sponges most likely be found making their home? | [
"a great pyramid",
"a rotting ship",
"a ski lift",
"a skyscraper"
] | B | an ecosystem contains nonliving things |
OpenBookQA | OpenBookQA-1805 | 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.
One arctic animal, the polar bear may spend their time doing what | [
"racing",
"swimming",
"creating",
"reading"
] | B | arctic animals live in an arctic environment |
OpenBookQA | OpenBookQA-1806 | zoology, sensation
Title: Can animals that rely heavily on sonar sense colour? Apparently there're species around as rely heavily on sonar to sense the world around them.
E.g. Bat, Dolphin, Whale ...
The humans, and other terrestrial beings in a lighted world are capable of distinguishing colour in varying degrees of acuity. Is this ability to sense colour in our environment applicable to species (terrestrial, avian, and marine) that rely heavily on sonar? Any animal using sound cannot sense color though sonar directly, though these animals are not entirely blind and can probably see colors in the infrared we can't.
Even on the darkest night there is some light around and all bats use this. Old World fruit bats have colour vision, which is useful to them as they are often quite active in daytime, roosting on trees in exposed positions, rather than tucked away in dark crevices like most microbats, which can see only in black-and-white.
Dolphins have additional senses in addition to seeing they can sense electrical fields. So if an animal has its eyes covered, they will seem to be able to do things you would not expect. Its not the same as seeing the color though.
Such animals using sonar can additionally sense density and hardness as well as other material attributes which would cause the acoustic properties of the material as well as movement.
A hard-bodied insect produces a different quality of echo from one with a soft body, so bats can distinguish between some different groups of insects in this way. They can also determine the size of the object.
What's really interesting is that even human beings can experience this unusual sense. Blind people have learned to echolocate by making clicks with their mouth, and there is a movement to teach this skill.
Anyone can try it. In just an hour or two I was able to tell how close I was to a wall, whether the wall was concrete. I couldn't play video games (2:20 on the link) or see colors though.
The following is multiple choice question (with options) to answer.
A bat may use echolocation to | [
"the grocery store",
"call a friend",
"track a moth",
"a concert"
] | C | echolocation is when some animals detect objects by hearing echoes by emitting sound |
OpenBookQA | OpenBookQA-1807 | electromagnetism, energy, electric-circuits, electric-current
Title: Why is dissipation of electric power as heat minimized? For a given electric circuit, currents and voltages are distributed to minimize the total power dissipated as heat. It seems that, there is some kind of action which is stationary.
What is the reason for this? Although your question is indeed unclear and also contains a statement which is not universally true lets try thinking about a few things;
The currents and voltages in a circuit are determined by the electrical properties of the parts of the circuit, primarily the supply voltage and the various resistances. It is always possible to calculate by equations, like Ohm's Law, what the voltages and current are in any place in the circuit. There is no magic distribution to minimise anything. Power dissipation occurs in all parts of the circuit and again it is possible to calculate it with formulae.
In the real world when designing electrical systems or circuits we may very well wish to minimise power dissipation in some parts. This is usually due to the fact that the heat is wasted, useless and may affect other things and, of course, costs money. In deciding on the design of such systems the choice of voltage and current may well be considered to keep unnecessary heat loses to an acceptably low level.
One example would be the design of a system to transmit 200MW of power from a power station to a town 50km away. Choosing a higher voltage for the transmission cables would result in lower current and hence lower heat loss in the cable all other things being equal.
If however I am designing an electric storage heater I would be wanting to maximise the heat produced by the electric current !
The following is multiple choice question (with options) to answer.
Electricity causes less pollution than what? | [
"sound",
"car propellant",
"water",
"sunlight"
] | B | electricity causes less pollution than gasoline |
OpenBookQA | OpenBookQA-1808 | zoology, digestive-system, pets
Title: Is it safe to feed an adult fire salamander with slime maggots? As a reminder, maggots feed of a flesh, while fire salamander consumes his prey alive, without killing it.
Can it happen that the maggot will start eating the salamander from the inside? Although I am afraid I don't know much about fire salamanders specifically, it is certainly possible for ingested fly larvae (or larvae hatching from ingested eggs) to survive ingestion and subsequently cause intestinal damage. Parasitic infestation by fly larvae that grow inside the host while feeding on its tissue is called myiasis. Enteric myiasis (also called gastric, rectal, or intestinal myiasis to indicate the affected part of the digestive system) occurs occasionally in humans following the ingestion of cheese infested with cheese fly maggots. Casu marzu, a traditionally produced Sardinian cheese, is supposed to have live cheese fly maggots in it, and cases of bloody diarrhoea following its consumption are known. If they're dead the cheese is considered unsafe to eat (although personally I'd correct that to 'more unsafe').
The following is multiple choice question (with options) to answer.
Which eats dead organisms? | [
"Canadian nightcrawlers",
"clouds",
"satellites",
"robots"
] | A | decomposition is when a decomposer recycles nutrients from dead organisms to the soil by eating those dead organisms |
OpenBookQA | OpenBookQA-1809 | orbit, earth
Title: Average amount of annual daylight at any place on earth If this is the wrong group please direct me to the correct one.
It seems intuitively obvious that the amount of daylight per annum should be the same for any latitude on earth. For example, 12 hours per day at the equator. The poles have daylight for half the year and darkness for the other half (crudely).
Is there any way to get an answer to this apparently simple question - is the annual amount of daylight the same at any point on earth? Wikipedia strikes again:
The naive expectation is that, for every place on Earth, the Sun will
appear to be above the horizon for exactly half the time. Thus, for a
standard year consisting of 8760 hours, apparent maximal daytime
duration would be 4380 hours. However, there are physical and
astronomical effects which change that picture. Namely, atmospheric
refraction allows the Sun to be still visible even when it physically
sets below the horizon line. For that reason, average daytime
(disregarding cloud effects) is longest in polar areas, where the
apparent Sun spends the most time around the horizon. Places on the
Arctic Circle have the longest total annual daytime of 4647 hours,
while the North Pole receives 4575. Because of elliptic nature of the
Earth's orbit, the Southern Hemisphere is not symmetrical: Antarctic
Circle at 4530 hours receives 5 days less of sunshine than its
antipodes. The Equator has the total daytime of 4422 hours per
year.
Further details here on astronomical causes of average daytime variation, and here on Insolation, the solar radiation received at the top of the atmosphere and its effects on the energy received at ground level.
The following is multiple choice question (with options) to answer.
How many divisions of particular weather patterns and hours of daylight is a year divided into? | [
"4",
"long",
"3",
"12"
] | A | a new season occurs four times per year |
OpenBookQA | OpenBookQA-1810 | 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.
Herbivores like to dine on | [
"gravel",
"other herbivores",
"crustaceans",
"chlorophyll"
] | D | cows only eat plants |
OpenBookQA | OpenBookQA-1811 | physical-chemistry, color, light
Title: Colour due to transmission and reflection It makes sense to me that when looking through a sample (observer | sample | light), it should appear as the opposite of the light absorbed, but it does not make sense to me to expect the same when not looking through it, just standing by the same side as the light source (observer | light | sample, or light | observer | sample).
In the first cenario, the observer sees light emitted - light absorbed (the transmitted, that barely interacts with the sample). In the second, the observer sees light reflected (to my understanding, light emitted from the de-excitations of excitations caused by the light source).
However, when I see a solution of $Cu^{2+}$, it looks the same when observed in both settings. Thereby implying that transmitted colour = reflected colour. Why is that?
Somewhat related question but without a satisfactory answer: Transmission, absorption, and reflection of light Since your experimental observation with copper salts negates your original hypothesis, it implies that the way you are trying to explain it is wrong. The main culprit and the source of all these problems is the color wheel which is taught in schools. Misconceptions persist for long. When you are looking at the copper solutions in two different settings, it is misleading to think that copper solution is reflecting blue light back to you. It is not.
In each case, copper(II) solution is absorbing a small portion of the red light from the visible spectrum and it appears to you like a pure blue solution.
Indeed it is our brain which has been created in such a way that when the visible spectrum has a certain red portion missing, it perceives the remaining spectrum as "blue".
Hint: Water in the ocean also appears blue? Water also very very weakly absorbs the red portion of the visible spectrum. You just need tons of water to perceive this effect.
There is a beautiful book by the name of The Physics and Chemistry of Color. The same author wrote an article "The fifteen causes of color: The physics and chemistry of color." It is certainly worth consulting. Article-behind paywall
The following is multiple choice question (with options) to answer.
the color of an object can be discovered by | [
"seeing it",
"touching it",
"sniffing it",
"licking it"
] | A | the color of an object can be discovered by looking at that object |
OpenBookQA | OpenBookQA-1812 | newtonian-mechanics, newtonian-gravity, optimization
Title: Maximal Gravity I found this interesting problem in Introduction to Classical Mechanics with Problems and Solutions by David Morin:
Given a point $P$ in space, and given a piece of malleable material of constant density, how should you shape and place the material in order to create the largest possible gravitational field at $P$?
Any ideas? This Physics quiz website by Yacov Kantor provides the solution in the February 2002 quiz. The optimal surface profile (with max gravity in the origin) in spherical and cylindrical coordinates for the solid of revolution is $r^2=z_0^2 \cos\theta$ and $(z^2+\rho^2)^{3/2}= z_0^2z$, respectively, $0\leq z\leq z_0$. The gravity in the origin is only 2.6% larger than the gravity on the surface of a spherical planet.
The following is multiple choice question (with options) to answer.
Which would have the most gravity? | [
"a metric ton of marbles",
"a blue whale and its calf",
"Jupiter and all its moons",
"a ball of burning gas in our solar system"
] | D | non-contact forces can affect objects that are not touching |
OpenBookQA | OpenBookQA-1813 | Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
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Re: At a certain carpet factory, if carpeting of width 10 feet is moving c &nbs [#permalink] 05 May 2018, 02:44
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The following is multiple choice question (with options) to answer.
You can scuff your socked feet on a shag carpet and shock a friend because of | [
"electromagnetism",
"electric youth",
"bad breeding",
"gravity"
] | A | non-contact forces can affect objects that are not touching |
OpenBookQA | OpenBookQA-1814 | climate-change, sea-level, glaciology, ice-sheets, antarctica
Title: Where does the biggest land-based ice cap reside? I'm thinking biggest in volume, regarding which area of the planet will contribute more to a raising in sea level - were the ice in those regions to melt.
I can basically think of two candidates, namely Greenland and Antarctica. So maybe some comparison between the contributions of the two would be great. Antarctica is the ice sheet (cap) that will contribute most IF it would melt completely. The 2013 IPCC report (Ch. 4, the Cryosphere) provides an estimate of 58.3 m of sea level equivalent (sle). Greenland would if completely wasted away provide 7.36 m sle. Remaining glaciers provide an additional 0.41 m sle. The likelihood of Antarctica completely wasting away seems unlikely with our current understanding although the so-called West Antarctic Ice sheet (closes to the Antarctic Penninsula is sitting with its base deep below the current sea level) is far more likely to be lost than the East Antarctic Ice Sheet. Hence the contribution from Antarctica is likely less than the maximum number. Greenland on the other hand is thought to have a "point of no return" beyond which it will irreversibly be lost given the current or warmer climate. Since Greenland is mostly land-based, much of the mass loss will be by surface melting while West-Antarctica can lose much of its mass by ice berg calving which is likely a much faster loss mechanism. Estimates on the scenarios are emerging but there are still uncertainties and there may also be feedbacks that we either do not fully understand or have not yet seen that can change these scenarios (particularly for West-Antarctica). This Science article
published online May 12 2014 is a good example of emerging research on the stability issues of West Antarctica.
The following is multiple choice question (with options) to answer.
Which land type is covered in snow for the largest portion of the year? | [
"tiaga and",
"prairie",
"deciduous forest",
"desert"
] | A | cold environments are usually white in color from being covered in snow |
OpenBookQA | OpenBookQA-1815 | 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.
How might a dresser crab avoid attention in an aquarium containing pieces of velvet and necklaces made of colorful stones? | [
"hold a vibrant piece of cloth and wave it rapidly back and forth",
"display bright colors to stand out to the fish",
"transform into a bureau replete with clothing",
"disguise itself as just some junk on the bottom of the tank"
] | D | An example of camouflage is when an organism looks like its environment |
OpenBookQA | OpenBookQA-1816 | classical-mechanics
the other car hits you and starts compressing your car's crumple zone.
the collision force exceeds your braking force and your car starts accelerating. Your car's crumple zone is still being compressed.
the crumple zone is fully compressed so both cars are now moving at the same speed and your brakes are slowing both cars.
During phase 1 your car is stationary so you feel no force. If the collision is low speed the other car may come to rest before your car starts to skid, and you feel no force at all.
However all but the most trivial collisions are likely to apply more force than your brakes can resist, and you enter phase 2. To calculate the force you feel in phase 2 is quite involved as you'd have to know the force distance curve for compression of the crumple zone. I did Google to see if I could find this data, but without success. Anyhow, it should be obvious that the force during phase two will be less than you'd feel if the brakes weren't on.
Phase three is interesting because it's where you get the whiplash. Assuming your headrest is properly adjusted your head won't move much in phase two. However when you enter phase three your own brakes will jerk you forward. To reduce this (and as above assuming there are no 18 wheelers around) you should release the brakes.
So for low speed collisions you should leave the brakes off, but for high speed collisions hit the brakes during the collision and release them as soon as the two cars have stopped moving relative to each other.
Having said all this, the collision you describe happened to me a few years ago (I'm sure it's hapened to lots of us) and I hit the brakes and held them on. I'm happy to report I suffered no harm, though my car was a write-off. I would advise my children to always hit the brakes and leave them on. Risking whiplash is better than being pushed across the junction or into the back of the car in front of you.
The following is multiple choice question (with options) to answer.
A child smacks another child, causing hurt, which causes the smacked child to | [
"play",
"eat",
"rejoice",
"sob"
] | D | harming something has a negative effect on that something |
OpenBookQA | OpenBookQA-1817 | botany, plant-physiology, plant-anatomy
Title: Caudex vs Xylopodium difference I live in Brazil and many plants from the brazilian grasslands/prairies exhibit an structure called, by the brazilian literature, "xylopodium" (or "xilopódio" in portuguese) - which are tickened, underground, lignified structures (root or stem) to store water and nutrients. I couldn't really find any work outside Brazil that mentions this kind of strucutre, and as far as I know, the structure known as "caudex" fits the very same definition. That being said, are these two terms synonyms? The New York Botanic Garden gives the definition of xylopodium as:
An underground, woody, storage organ derived from stems or roots and common in cerrado vegetation.
And the definition of caudex as:
A short, vertical, usually woody and persistent stem at or just below the surface of the ground.
I think the main difference here is the focus on the xylopodium as a storage organ, as well as the fact that it is fully underground and can be derived from either the stem or root. A caudex doesn't necessarily primarily provide storage, and as a modified stem, is at or above the surface.
*There is also a definition of xylopodium meaning the type of fruit found in Anacardium (cashews).
The following is multiple choice question (with options) to answer.
A cactus stem is used to store what? | [
"mp3s",
"H2O",
"sand",
"seeds"
] | B | a cactus stem is used for storing water |
OpenBookQA | OpenBookQA-1818 | anatomy, scales
If this horse is 500 kg (a mid-range mass for horses), each leg would have to support 125 kg, compared to only 37.5 kg for a 75 kg adult. Why don't we see a corresponding difference in cross-section? Elephant, rhinoceros, &c all have much thicker legs in proportion. The answer, I think, lies in the fact that the animals you mention all evolved as cursorial animals (that is, they run to escape predators). Less mass in the lower leg means it swings easier, so the animal can run faster.
There are two things you're apparently not noticing in that picture. First, the the horse's lower leg is almost entirely bone (and some tendon), and it's bone that does the supporting. The propulsive power comes from the large muscles of the hip, thighs, and shoulders.
Second, the lower part of the leg (with the white wrappings) is not anatomically equivalent to the human's lower leg, but to the bones of the hand and foot. You can see this if you look closely at the rear leg in that picture. The femur, equivalent to the human's thigh, ends at the knee just above the belly line. Then the tibia extends about halfway down, ending at another joint which you might think is the knee, but which is called the 'hock' in horse-speak. The white-wrapped part is a metatarsal, equivalent to human foot bones, then there pastern bones equivalent to human toe bones, ending in the hoof/toenail.
So consider that you can, if reasonably fit, walk around on tiptoe without crushing your foot and toe bones, then imagine the end result of your ancestors having done this for the last several tens of millions of years :-)
PS: With horses, there is some effect from human selection, too. Racing & show breeds tend to have thin lower legs, draft horses & working breeds have proportionately thicker ones. My first horse, a thorobred/arab mix, had legs about as thick as my wrists (granted, I'm a fairly muscular guy); my current mustang, about the same height & weight, has legs about twice as thick.
The following is multiple choice question (with options) to answer.
An animal will become thicker if it does all aside from | [
"gorge",
"refuse food",
"feed",
"eat food"
] | B | as the amount of food an animal eats decreases , that organism will become thinner |
OpenBookQA | OpenBookQA-1819 | pressure, everyday-life, physical-chemistry, vacuum
Extra: Is this (your answer) also a reason for not semi-compressing half-full flexible plastic cola bottles before closing them? Creating a vacuum above carbonated drinks causes the CO2 to outgas faster--simply because there is no CO2 above the drink to diffuse back into the liquid. In physical terms this means there is no vapor pressure of CO2 above the liquid, so net movement of CO2 is from the drink to the space above it. If you leave a closed carbonated drink bottle long enough, the partial pressure of CO2 in the drink and in the space above the drink are the same--rate of gas that escapes the drink is equal to the rate that dissolves back into it--equilibrium.
Note that it is not solely about gas pressure but partial pressure of the gas you are interested in. Pressurising your champagne bottle with pure air to above atmospheric and sealing it wont extend the bubblyness. You need to pressurise with CO2 gas. For soft drinks you need 2 bar CO2 (in a typical coke bottle left alone for awhile, the space above the drink is almost pure CO2 and is at 2bar).
Your question about PET bottles is a good one. As mentioned, without a CO2 pump you cant extend the life of your sodas. Squeezing a half full bottle and sealing it removes the volume of available space above the drink, so when CO2 inevitably escapes the liquid to form equilibrium vapor pressure above it, less CO2 is required for this to happen--if the bottle doesnt expand back. The problem is that the bottle has structurual integrity and is designed to spring back. This creates low pressure in the bottle, causing CO2 to outgas faster than if you hadn't done all this in the first place. The upside is that equilibrium is the same--you lose the same amount of CO2 from the drink as if you had not done this. To really save gas, when you squeeze the bottle and seal it, you have to find a way to keep the bottle from springing back. Or just store unfinished soda in bottles where there is very little space for CO2 to outgas into.
The following is multiple choice question (with options) to answer.
If you want to bottle your own pop, you should invest in | [
"Andy Warhol paintings",
"an aluminum mine",
"blonde dye bottles",
"a telescope"
] | B | a soda can is made of aluminum |
OpenBookQA | OpenBookQA-1820 | anatomy, scales
If this horse is 500 kg (a mid-range mass for horses), each leg would have to support 125 kg, compared to only 37.5 kg for a 75 kg adult. Why don't we see a corresponding difference in cross-section? Elephant, rhinoceros, &c all have much thicker legs in proportion. The answer, I think, lies in the fact that the animals you mention all evolved as cursorial animals (that is, they run to escape predators). Less mass in the lower leg means it swings easier, so the animal can run faster.
There are two things you're apparently not noticing in that picture. First, the the horse's lower leg is almost entirely bone (and some tendon), and it's bone that does the supporting. The propulsive power comes from the large muscles of the hip, thighs, and shoulders.
Second, the lower part of the leg (with the white wrappings) is not anatomically equivalent to the human's lower leg, but to the bones of the hand and foot. You can see this if you look closely at the rear leg in that picture. The femur, equivalent to the human's thigh, ends at the knee just above the belly line. Then the tibia extends about halfway down, ending at another joint which you might think is the knee, but which is called the 'hock' in horse-speak. The white-wrapped part is a metatarsal, equivalent to human foot bones, then there pastern bones equivalent to human toe bones, ending in the hoof/toenail.
So consider that you can, if reasonably fit, walk around on tiptoe without crushing your foot and toe bones, then imagine the end result of your ancestors having done this for the last several tens of millions of years :-)
PS: With horses, there is some effect from human selection, too. Racing & show breeds tend to have thin lower legs, draft horses & working breeds have proportionately thicker ones. My first horse, a thorobred/arab mix, had legs about as thick as my wrists (granted, I'm a fairly muscular guy); my current mustang, about the same height & weight, has legs about twice as thick.
The following is multiple choice question (with options) to answer.
Sea horses require | [
"leather harnesses",
"jockeys",
"black stallions",
"the sun"
] | D | the sun is the source of energy for life on Earth |
OpenBookQA | OpenBookQA-1821 | 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.
dead organisms are the source of what for decomposers? | [
"place to sleep",
"art",
"friendship",
"sustenance"
] | D | dead organisms are the source of nutrients for decomposers |
OpenBookQA | OpenBookQA-1822 | newtonian-mechanics, forces, rotational-dynamics, friction, free-body-diagram
Title: How does friction stop a car? I'm unable to understand how friction causes motion in cars and also is responsible for stopping them.
When it starts the impending motion of tyres is in the backward direction that's why friction is in the forward direction and the car starts moving.
But when the car engine turns off, the car stops after some time, but the condition of tyres are the same as in the previous case and friction must be in the forward direction. It is not the same friction, but rather the friction between the wheels and the breaking pads (and in general between the rotating parts of the car and their supports.)
The following is multiple choice question (with options) to answer.
Friction is used to stop what using brakes? | [
"dogs",
"birds",
"pickups",
"car toys"
] | C | friction is used for stopping a vehicle by brakes |
OpenBookQA | OpenBookQA-1823 | education
Finally, be open to all possibilities, since you can't know what opportunities that might open. A number of years ago, I heard from a CS major I had taught who had become a successful rodeo clown. Did he use his major? Nope. Was he happy with his life? It certainly appeared so. The single most important lesson I teach my students is, get a job you love, then you'll never have to "work" a day in your life. Best of luck.
The following is multiple choice question (with options) to answer.
A person will go through many stages in life, some more fun than others. Considering these stages, all are real aside from | [
"physical maturation",
"infancy",
"fishinghood",
"childhood"
] | C | adulthood is a stage in the life cycle process |
OpenBookQA | OpenBookQA-1824 | electromagnetic-radiation, scattering
Title: Clarification on Rayleigh scattering causing various sky colors (I know Rayleigh scattering isn't the only reason why the sky is blue but to simplify the question lets focus on that)
The commonly stated reason for why the sky is blue is that smaller wavelengths are scattered more easily off the molecules in the air. During the day, because the blue light is scattered more, the sky is illuminated more with that blue light and more reaches your eyes. However, during sunsets and sunrises, the light from the sun must travel a longer distance. The explanation I have found is that the blue light is scattered away and more of the longer wavelength reds and greens are available to reach your eyes to get those warmer colors, (red and green of course mixing to get yellows).
My question is that it seems like these explanations are conflicting. If the light at sunsets and sunrises travels more distance, why won't the blue light be scattered even more and thus illuminate the sky with blue light more than in the daylight? It confuses me that in one case the scattering of blue light causes the sky to be blue but then at sunset the scattering eliminates this color. Could I get some explanation on this? When the Sun is directly overhead, the light is going through about the equivalent of 8km of sea-level air, even though the atmosphere is roughly 50km high.
When the Sun is just on the horizon, it’s 15 times as far to that 50km height, with approximately the same density profile: there about 120km of sea-level-equivalent air, or about 15 times as much.
A lot more blue-end light is scattered away at sunset, 15X, leaving a redder sun.
Why don’t you see it, I.e. why isn’t the setting-sun sky bright? It’s because the scattering isn’t near you. With the sun overhead, most of the scattering is a few km up, which sets the typical distance. At sun set, that same scattering happens 100’s of km away as the light slants in. Yes, that makes the sky blue, but not your sky: it gives the bright blue to people who still have the sun high in the sky.
The following is multiple choice question (with options) to answer.
A person knows that a place always has blue skies, warm weather and a light breeze because | [
"that is the beach",
"that is the meaning",
"that is the religion",
"climate is fairly reliable"
] | D | climate is the usual kind of weather in a location |
OpenBookQA | OpenBookQA-1825 | 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.
As a snowball grows it will require | [
"a dog sled team to pull it",
"a stronger person to push it",
"a large vat of chocolate syrup to dump on it",
"a group of blind Eskimos to move it"
] | B | as the mass of an object increases , the force required to push that object will increase |
OpenBookQA | OpenBookQA-1826 | species-identification, fruit
Title: What is this plant with hardened fruits on the beach in Mozambique? We saw these near the Barra and Tofinho beaches in the Inhambane province in Mozambique, in July. They were hard and leathery and dry to the touch, long past something resembling edible fruit.
Anybody have an idea what they might be? (just curious)
Edited: Here is some context around the tree. I will take a guess that it is Ficus racemosa which is found in that area. More info. If you have pictures of the rest of the tree that would be helpful.
The following is multiple choice question (with options) to answer.
Where is fruit made? | [
"in several farmers markets",
"in fruit bat caves",
"on the stems of trees or vines",
"in organic food stores"
] | C | plants are the source of fruit |
OpenBookQA | OpenBookQA-1827 | inorganic-chemistry, solubility, metallurgy
Any insights would be much appreciated! Let me give an extreme example of chemical analysis. It is an anecdote. Some analytical chemists were using a very sensitive technique to analyze metals in blood. It is called neutron activation analysis. What they saw was that a very small quantity of molybdenum (Mo) was present in small quantities persistently. Nobody expected that. It turned out after a lot of hard work that Mo was coming from the stainless steel syringe needle used for drawing blood. Lesson of the story: There is nothing which is perfectly insoluble in water. It all depends on the analytical technique. If you try to weigh a hair on a "weighing machine" it will tell you that the mass is zero kg, but if you use a fine analytical balance it will tell you that hair has a mass.
The same goes for lead pipes. Natural water has plenty of minerals, dissolved oxygen anions, cations and don't forget the microorganisms. The bacteria do a lot of chemical transformations in water. As a result, Pb would slowly leach into the water at parts per million or parts per billion levels. Don't assume that Romans were drinking lead salt solutions in high concentration ranges. Not only water lead was present in water, it was also present in alcoholic beverages.
Read more here Lead in ancient Rome’s city waters
Lead in water is still a serious problem in several areas of the modern world. It is not an ancient problem.
The following is multiple choice question (with options) to answer.
To discover how durable a certain mineral may be, one could | [
"crush it in a vise",
"view the atomic weight of it",
"attempt to leave a mark on it",
"melt it down and pour"
] | C | measuring the hardness of minerals requires scratching those materials |
OpenBookQA | OpenBookQA-1828 | climate-change
Source: World Meteorological Organization Press Release No. 976: 2001-2010, A Decade of Climate Extremes
The above image speaks for itself. The global temperature change over the last forty years is very real, and is not noise.
With regard to point #2, yes the climate has changed in the past, and by huge amounts. We've had everything from snowball Earth to dinosaurs roaming the Arctic. And the point is? This argument is akin to a farmer taking a trip to the Grand Canyon and upon seeing what damage nature can do decides to forgo contour plowing and other anti-erosion farming techniques.
That the farmer's field might turn into a mountain or be washed out to sea several millions of years from now is irrelevant. What's relevant is that his good or bad practices have an impact on the world food supply. That nature can do far worse does not negate those bad farming practices. Bad farming practices are bad for humanity.
Getting back to climate change, if higher global temperatures are bad for humanity, it doesn't matter matter one bit how close ice came to the equator or how far north dinosaurs roamed in the past. What matters is that modern humanity is sensitive to climate change, be it natural or induced by humans.
With regard to point #3, yes, weather becomes chaotic after ten days or so. That does not mean that climate is chaotic, and if it is, the ~ten day Lyapunov time of the weather does not mean that climate also has a ten day Lyapunov time.
With regard to point #4, it is CO2. It was amusing to follow the skeptic response to Richard Muller's Berkeley Earth Surface Temperature project. Muller was a self-proclaimed skeptic, and he was going to prove those leftist climatologists wrong. The skeptic community cheered at the start.
"He's going to prove them wrong!" A funny thing happened on the way to proving them wrong: He proved them to be correct. Muller was an honest scientist in this regard. His own work caused him to switch from being a skeptic to ascribing to AGW.
The following is multiple choice question (with options) to answer.
An environment is likely to change when humans | [
"make a building taller than before",
"remodel and existing house",
"clear hillside brush for houses",
"have more people living in one house"
] | C | humans building homes in an ecosystem causes that environment to change |
OpenBookQA | OpenBookQA-1829 | geology, geomorphology, coastal
Title: What causes such a narrow slit in a cliff? (see photo)
I have this photo as a background image and I often wonder how such a narrow, well-defined slit could be formed. Is it natural or man-made? If natural, what processes could have formed it? The rest of the coastline is rugged but this appears very uniform. It is on the north-west coast of Jersey (UK). If you see the other user (Jan Doggen's) google maps link, you can see apparently similar features in different states - this is a particularly neat example of a general phenomenon.
These notches form when headlands are undercut by caves carved out by the sea. They may be initiated where there is a fault or jointing in the rock (northwest Jersey is granite, according to google).
In this particular case, the notch seems to have a rounded termination. Blowholes also form from undercutting of headlands producing caves whose roofs then collapse. It's possible this cave may have collapsed after a blowhole formed, so you get a notch where the inland end of the feature appears rounded. That bit is just speculation though.
I found this Jersey geology trail guide that might have more detail: http://jerseygeologytrail.net/Geomorph.shtml
The following is multiple choice question (with options) to answer.
One component of rock formations in caves is | [
"liberal tears",
"bat urine",
"salty ocean water",
"granite statues"
] | B | stalactites are formed by deposition |
OpenBookQA | OpenBookQA-1830 | infection, amphibians
Title: What is this toad suffering from? Myiasis or chytridiomycosis? I found this toad on Aug. 29th at this location: position on osm
I think it is a bufo bufo, approx. 10 cm long. The nostrils seemed to be completely filled with a grey matter and from the activity of the floor of the mouth it apparently tried to breathe againgst this obstruction. It probably had enough oxygen via its skin though.
I tried to remove the obstruction using a blade of grass but this seemed to produce some pain as the toad closed its eyes on contact, so I stopped. The skin looked fairly normal and the toad was able to walk away after a while.
I can think of two causes for this condition.
Batrachochytrium dendrobatidis infestation
Lucilia bufonivora larvae
I could not see properly, if there were any larvae or unhatched eggs inside the nostrils, but as the rest of the skin seemed unharmed I assume the latter.
Is my assumption valid or is there even a third possibility? It is a female Bufo Bufo and you are right, there are toad fly (Lucilia bufonivora) larvae/eggs inside her nostrills. These flies lay their eggs inside toads' nostrills (specifically on Bufo Bufos) and the larvae start eating them. Sadly this disease ends up by the death of toad. They slowly eat nostrills, then mouth, eyes, and all the head.
Here's a photo of a male bufo bufo, without a head. Someone found it walking around at this situation. https://i.stack.imgur.com/I6twl.jpg
The following is multiple choice question (with options) to answer.
Dormant cane toads emerges from mud to ended their | [
"long slumber",
"day",
"life",
"meeting"
] | A | when a hibernating frog emergest from mud , that frog has ended its hibernation |
OpenBookQA | OpenBookQA-1831 | thermodynamics, photoelectric-effect, thermal-conductivity, absorption, solar-cells
Title: Possibility of combining photovoltaics and solar thermal energy In a private setting, photovoltaics and solar thermal energy are often harvested on the home's roof and roof area is limited. So, I thought about combining both, i.e. mounting solar collectors underneath solar cells. The rationale behind this is that the solar cells appear almost black and probably heat up considerably under irradiation. So if the collectors are in tight thermal contact to the cells, the water in the collectors might carry away the heat as usable energy, and possibly even increase the lifetime or efficiency of the cells due to the cooling effect (but this is rather engineering and not part of the question). So roof area is exploited twice (in two different wavelength windows). Moreover, if electric energy from the cells exceeds actual consumption and the battery's storage capacity, it might also be used for heating (albeit at a lower total efficiency, of course).
Can the amount of (infrared) radiation that gets absorbed (or possibly transmitted) by solar cells, and which is available as heat at the back side of the cells, be quantified by a rough calculation and either prove or disprove the benefit of such a concept? Does the almost black appearance of the solar cells fool one into thinking that they also absorb in the infrared, although they don't? Temperature of PV panels increases significantly during the day and their conversion efficiency decreases with increasing temperature. I had access to measurements of a PV plant and it showed that the total power production was about the same in August (middle of summer) and October (early fall). Although the days were shorter and there was less solar irradiance in October vs August, the air temperature was significantly lower making PV panels more efficient. For the outside temperature of 35 C, the PV panels can easily reach 70 C!
The following is multiple choice question (with options) to answer.
Heat energy has been added to | [
"red velvet cupcakes",
"Greek yogurt",
"ceviche",
"Caesar salad"
] | A | if food is cooked then heat energy is added to that food |
OpenBookQA | OpenBookQA-1832 | home-experiment, food-chemistry, color
For cooking food, this above synthesis method seems unreasonable and overkill. I urge you to experiment with a few methods of forming the red curcumin-phospholipid complex yourself, with soy lecithin/eggs. I would have tried some methods out but I don't have these ingredients at home. see edit.
The advantage of having curcumin in a liposome is that it is much more stable: unlike the acid-base action, curcumin in a liposome remains stable across a wider range of pH's, as shown in this graph. This method does show promise, but as I mentioned, you would have to give this a try yourself.
Other practical solutions
Seasoned Advice would probably give you would get a better answer in this field, but I'll drop in my two cents. Generally, chilli powder is used to provide the red colour to Tandoori. More specifically, Kashmiri chilli powder is specifically used for tandoor preparations, such as tandoori chicken and chicken tikka. This powder is applied as a dressing (in combination with oil, rice flour etc after cooking the food) and during marination (chicken is marinated with curd, red chilli powder and turmeric).
Happy cooking!
References:
Kuntal Maiti, Kakali Mukherjee, Arunava Gantait, Bishnu Pada Saha, Pulok K. Mukherjee; Curcumin–phospholipid complex: Preparation, therapeutic evaluation and pharmacokinetic study in rats, International Journal of Pharmaceutics, Volume 330, Issues 1–2,
Sam-ang Supharoek, Kraingkrai Ponhong, Watsaka Siriangkhawut, Kate Grudpan;
Employing natural reagents from turmeric and lime for acetic acid determination in vinegar sample, Journal of Food and Drug Analysis, Volume 26, Issue 2,
Hong-Hao Jin, Qun Lu, Jian-Guo Jiang; Curcumin liposomes prepared with milk fat globule membrane phospholipids and soybean lecithin, Journal of Dairy Science, Volume 99, Issue 3,
Research gate: Why does curcumin have a red colour in the alkaline condition
Wikipedia: Phospholipids, Curcumin
The following is multiple choice question (with options) to answer.
Where might you find the primary ingredient for making grilled rabbit in a spicy marinade? | [
"a spacious area mostly covered with trees and undergrowth",
"inside of an AA battery",
"an enclosed bank vault",
"at the bottom of a bleached coral reef"
] | A | some rabbits live in forests |
OpenBookQA | OpenBookQA-1833 | ornithology, kidney
Back to worrying about the mammal-centric thinking: there is a causal implication in both the original and my edited version that is not warranted, which is that the anatomy of the loops of Henle is somehow determining the nitrogen excretion strategy that birds use. It's equally reasonable to presume that birds don't need long loops of Henle since they evolved an alternative excretion mechanism that makes it unnecessary to concentrate urine to a great degree.
The "trick" of that alternative excretion mechanism is using uric acid and excreting a paste. Because uric acid crystalizes and comes out of solution, it doesn't "count" toward osmolarity of the urine, it's excreted as a solid. Birds don't need to remove water to crystalize uric acid, and don't need to use water to flush it out at all, it falls out of solution on its own because it's not very soluble. You could add a bunch of extra water and it would still stay mostly solid rather than dissolving.
So back to your original question: how do birds concentrate their urine? Well, pretty much the same way we do as far as the kidney goes. They also pull some water back in through the cloaca before urine is released, similar to how mammals pull water in from stool in the large intestine. The important difference is not how birds concentrate their urine (because urine concentration isn't a goal/need in itself), but rather how birds excrete nitrogen waste. By not flushing soluble nitrogenous waste with water in the first place, they don't have as much urine to concentrate, so it's less important for them to be very efficient in doing so.
The following is multiple choice question (with options) to answer.
A bird in an arid place can find water, despite a lack of puddles, lakes or rainfall if it | [
"pokes a tough plant",
"eats a small stone",
"takes out a loan",
"cries for a minute"
] | A | a cactus stores water |
OpenBookQA | OpenBookQA-1834 | This lets them bring a 15th bar and catch the train with less than 5 minutes to spare.
It is not possible to move all 16 bars.
Consider the total distance that each person moves, in each direction, carrying each possible number of bars. For example $$R_2^+$$ is the total distance that Rod moves forward while carrying 2 bars. We can set up a system of equations. Both Rod and Lia must move a net distance of $$1$$ mile forwards: $$R_0^+ - R_0^- + R_1^+ - R_1^- + R_2^+ - R_2^- = 1 \\ L_0^+ - L_0^- + L_1^+ - L_1^- = 1$$ Both of them must spend less than $$370$$ minutes moving (note we have taken the reciprocals of their speeds in minutes per mile): $$20(R_0^+ + R_0^-) + 30(R_1^+ + R_1^-) + 60(R_2^+ + R_2^-) \le 370 \\ 30(L_0^+ + L_0^-) + 40(L_1^+ + L_1^-) \le 370$$ Finally, the total net distance moved by all the bars must be $$16$$ miles forwards: $$R_1^+ - R_1^- + 2(R_2^+ - R_2^-) + L_1^+ - L_1^- = 16$$ And of course each distance must be nonnegative.
Next (thanks to RobPratt) we multiply these equations by $$\frac{1}{2}$$, $$\frac{3}{7}$$, $$\frac{1}{40}$$, $$\frac{1}{70}$$, and $$-1$$ respectively, and sum them, yielding:
The following is multiple choice question (with options) to answer.
A person going home would head | [
"to a cow",
"to a moon",
"to a jail",
"to a duplex"
] | D | some humans live in houses |
OpenBookQA | OpenBookQA-1835 | meteorology, climate-change, precipitation, climate-models
Can this process predict changes in 1000-year events? Yes, potentially, even when the projection period is usually more like 100 years. This is because 1 in 1000-year events are actually defined inversely - that is, they are thought to have a 0.1% chance of occurring in any given year. If your ensemble projects over 100 years, but has 100 simulations, then there are 10,000 years in which that a 1 in 1000 might occur. If you see it occurring 20 times, or 4 times, then you might get suspicious that things are changing. You probably need more than that to get a statistically significant result, but there are ensembles out there that are really big (e.g. Stainforth et al, 2005, which had 2,578 simulations totalling over 100,000 simulated
years, and I think some of the ClimatePrediction.net have tens of thousands of simulations). Even without those large ensembles, if you assume particular distributions of extreme events where probability is a simple function of extremeness (e.g. Log-normal distribution or similar), then you can probably say something about large extremes based on the change in behaviour of less extreme events. Unfortunately, I am not aware of any experiments that look at the likely changes to very extreme events.
The following is multiple choice question (with options) to answer.
There are many changes that can occur to the earth, quickly or overtime. Which would occur over millions of years? | [
"earthquake",
"canyon",
"tornado",
"Tsunami"
] | B | a canyon forming occurs over a period of millions of years |
OpenBookQA | OpenBookQA-1836 | 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.
A pond of frogs once contained | [
"pollywogs",
"sharks",
"princes",
"French people"
] | A | metamorphosis is a stage in the life cycle process of some animals |
OpenBookQA | OpenBookQA-1837 | audio, filter-design, noise, denoising
I did a quick dirty hack on that and found it sounded already a lot better (although certainly not clean either). Below is a picture that shows the first pulse before and after.
That's work in progress and there are certainly ways to refine this further.
The following is multiple choice question (with options) to answer.
Steve's ears alerted him to something. It was | [
"the taste of his lunch",
"waves in the air",
"the light streaming through the window",
"the feeling of his hair on his neck"
] | B | matter vibrating can cause sound |
OpenBookQA | OpenBookQA-1838 | the-sun, earth
Title: If the Sun got larger, but maintained its luminosity, would the Earth get hotter or colder? A recent question If the Sun were bigger but colder, Earth would be hotter or colder? asked - if the Sun got bigger and cooler, would the Earth heat up or cool down. I think the answer to that is mainly that it depends on the final luminosity.
However, what I want to know here (hypothetically), is if the Sun got larger and it's effective temperature decreased such that it's luminosity was unchanged; how would that affect the equilibrium temperature of the Earth? I suspect the answer may involve the wavelength dependence of the albedo, emissivity and atmospheric absorption of the Earth.
Another, less hypothetical, way of asking this is, if you put an Earth-like planet at different distances from stars with a variety of temperatures, such that the total flux incident at the top of the atmosphere was identical, how would the temperatures of those planets compare? The key issue is the opacity of the atmosphere, because I presume the question is about the temperature at the solid surface of the Earth. The atmospheric opacity can be seen from https://physics.stackexchange.com/questions/135260/can-someone-explain-to-me-the-concept-of-atmosphere-opacity, where you can see that the "rainbow" of maximum heat flux from the Sun happens to hit a kind of hole in atmospheric opacity. That has a significant warming effect on the Earth, and is exacerbated by the Greenhouse effect. If sunlight was further into the infrared, the graph shows that much more of it would be intercepted in the atmosphere. That would make the surface significantly colder, though certainly not a factor of 2 colder.
No doubt the question is of more than passing interest, because M dwarfs are the most numerous main-sequence stars and are therefore interesting for life. To have life near an M dwarf, the planet would need to be closer than Earth is to the Sun, but the effect of moving the planet closer and shrinking and cooling the star would be similar to leaving Earth where it is and making the star cooler and larger. So the nature of atmospheric opacity for wet atmospheres must be of great significance for understanding the prospects for life around M dwarfs.
The following is multiple choice question (with options) to answer.
The planet got warmer and warmer, and now the atmosphere is warm as well with the greenhouse effect | [
"holding elements near",
"locking acid in",
"locking in dogs",
"gassing in carton"
] | A | the greenhouse effect is when carbon in the air heats a planet 's atmosphere |
OpenBookQA | OpenBookQA-1839 | ### Show Tags
19 May 2015, 12:37
we have here 4 (4 years) successive increases of 25% or *1,25 --> 1,25^4 * X = 6250, X = 2560
See MGMAT (Percents) for detailed explanation of such question types.....
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Re: Each year for 4 years, a farmer increased the number of trees in a [#permalink]
### Show Tags
20 May 2015, 03:32
BrainLab wrote:
we have here 4 (4 years) successive increases of 25% or *1,25 --> 1,25^4 * X = 6250, X = 2560
See MGMAT (Percents) for detailed explanation of such question types.....
Dear BrainLab
Perfect logic but for easier calculation, you may want to work with ratio here (1/4 increase per annum) instead of percentages (25% increase per annum). Both convey the same thing but the equation
$$(\frac{5}{4})^4*X = 6250$$
will take lesser time to solve (especially if you know that $$5^4 = 625$$) than $$(1.25)^4*X = 6250$$
Hope this was useful!
Japinder
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Re: Each year for 4 years, a farmer increased the number of trees in a [#permalink]
### Show Tags
18 Jan 2016, 23:36
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Re: Each year for 4 years, a farmer increased the number of trees in a [#permalink] 18 Jan 2016, 23:36
The following is multiple choice question (with options) to answer.
the best way to improve production in future yields on the farm is | [
"planting cabbage one year and spinach the next",
"chemical fertilizers and salts",
"rotating water schedules daily",
"over watering each field"
] | A | crop rotation has a positive impact on soil quality |
OpenBookQA | OpenBookQA-1840 | Hey, thanks for your help guys. For a minute there, I thought that this theoretical person could not safely expect to live to be 82 years old.
9. Jun 16, 2012
### SW VandeCarr
In fact, on a purely probabilistic basis, for any finite time no matter how large, there is a non zero probability that a person would survive that long. So for a sufficiently large population, there would be a theoretic person that would live 100,000 years. This, of course, has no basis in biology.
In terms of the probability of being murdered, the model would not hold for the 100,000 year old person. In terms of the model, probably the best one can do is assume the proportion of causes of death would be constant. The calculation above needs to be corrected for overall survival in terms of death from any cause.
Last edited: Jun 16, 2012
10. Jun 16, 2012
### viraltux
Interesting... but 0.37% is not that small percentage, don't you think? That means, roughly speaking, that a community of around 300 persons can expect that one of them will be murdered.
If you consider that the number of people we know plus acquaintances can easily be around 300 persons that would mean that most 82 year old persons know of someone in their circles who has been murdered. Mmm... that might be an interesting survey.
11. Jun 16, 2012
### SW VandeCarr
As I said in my previous post, this is a misapplication of statistics. You have to consider survival in terms of all cause death. If you just consider the murder rate, then at some point nearly everyone gets murdered.
12. Jun 16, 2012
### moonman239
I know that.
This person will not die until he reaches age 82, if he is not murdered. As mentioned before, this person has a 68% chance of living to be 82.
13. Jun 16, 2012
### D H
Staff Emeritus
The probability of living to 82 per this problem is 99.63%, not 68%. You missed the decimal point on the 0.37%.
14. Jun 16, 2012
### SW VandeCarr
The following is multiple choice question (with options) to answer.
A being may have more of a chance of survival if it can | [
"dance like people are looking",
"climb up to tall places",
"hang out in large, loud groups",
"skateboard for long periods of time"
] | B | the ability to find resources has a positive impact on an organism 's survival |
OpenBookQA | OpenBookQA-1841 | lab-techniques, photosynthesis, chromatography
At the beginning, both cars (solutes) S1 and S2 are even with the solute front car (SF) because the race (chromatography) has just begun. However, over time, the SF car outpaces S1 and S2 because it is moving faster.
_______
/____/SF\___
|_,._____,._)
---`'-----`'--
_______
/____/S1\___
|_,._____,._)
---`'-----`'--
_______
/____/S2\___
|_,._____,._)
---`'-----`'--
And at the end, you get great separation:
_______
/____/SF\___
|_,._____,._)
---`'-----`'--
_______
/____/S1\___
|_,._____,._)
---`'-----`'--
_______
/____/S2\___
|_,._____,._)
---`'-----`'--
(Thanks to retrojunkies.com for the ASCII car)
The following is multiple choice question (with options) to answer.
A person wants to find chloroplasts in great amounts, so they check | [
"stems",
"buds",
"extended portions",
"dry seeds"
] | C | most chloroplasts are found in the leaves of a plant |
OpenBookQA | OpenBookQA-1842 | species-identification, entomology
Title: What kind of an animal is that?
Found in Austria. At half past nine p.m. in the summer/autumn. Due to the long legs and the shape of the abdomen, this is probably a crane fly, a dipteran from the Family Tipulidae.
Just for comparisson, here is Holorusia hespera:
Crane flies can be very large. I still remember the first crane fly I saw, in New Zealand: it seemed like a humongous mosquito (mosquitoes are dipterans from a different family, called Culicidae), it was quite impressive. Have a look at the size of this crane fly:
Despite their scary size, do not fear them. Unlike mosquitoes, crane flies are completely harmless: adults have a short life span, only days (just enough to reproduce), and in most species of crane flies adults don't eat at all.
Regarding the exact species of your specimen: the number of species in Europe is huge and, together with the fact that your photo is not the best one, it will be very difficult narrowing this down to Species, or even to Genus. Therefore, a better photo is necessary.
The following is multiple choice question (with options) to answer.
What lives in some zoo exhibits? | [
"animal statues",
"felines",
"extinct species",
"people"
] | B | some animals live in zoo exhibits |
OpenBookQA | OpenBookQA-1843 | 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.
Why might wolves a new area where a lot of deer live? | [
"The wolves eat the same things that the deer eat",
"They wanted to be friends with the deer.",
"The wolves stay near the deer for protection",
"The wolves use the deer for nutrition"
] | D | most predators live near the same environment as their prey |
OpenBookQA | OpenBookQA-1844 | 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.
Lettuce feeds rabbits by creating food with | [
"hamburgers",
"help from friends",
"chloroplasts",
"ordering out"
] | C | green plants provide food for consumers by performing photosynthesis |
OpenBookQA | OpenBookQA-1845 | homework-and-exercises, energy, energy-conservation
Title: Work being done without distance I have this issue:
If you push a 40.0 kg crate at a constant speed of 1.40 m/s across a horizontal floor
(µk=0.25 ), at what rate (a) is work being done on the crate by you and (b) is the
energy dissipated by the frictional force?
For starters, here is what I have so far:
RN = mg = 40*9.8 = 392 N
Ff = muRN = 0.25*392 = 98 N
KE = 0.5mv^2 = 0.5*40*(1.40)^2 = 39.2 J
At this point, I don't know how to answer part (a).
If W = FD , how do I find the work being done without a distance? SO work done by frictional force will be frictional force * distance trvelled per second or per minute in this it will be 137.2 Jules/sec. And work done by you will be the same because you are applying the force only to keep it moving not for accelerating it which in case would have been F=ma. And if you want to calculate the work done in travelling a particular distance then you wil be given the time interval in which you have to calculate it.
The following is multiple choice question (with options) to answer.
A mechanical device requires 420 J of work to do 230 J of work in lifting a crate. What is the efficiency of the device? | [
"65%",
"50%",
"60%",
"55%"
] | D | a simple machine requires mechanical energy to function |
OpenBookQA | OpenBookQA-1846 | everyday-life
Title: Why is it that when a chalk board gets cleaned, the area that used to have chalk is the cleanest? Why is it that when you erase a chalk board, the area where the chalk used to be becomes the cleanest? By that I mean that when you erase a chalk drawing, the board gets smeared with chalk dust, but the area where the drawing used to be has less dust on it than the rest of the board.
For example: In the first picture below I draw a simple chalk smiley face. Here the face is noticeable because it is the area with the most chalk. For the second picture, I erase it. You can still make out the picture, but notice that you recognize it because it is now the area with the least chalk.
I would expect that if chalk was stuck to a certain region of a chalk board, then after erasing it, some chalk residue would remain, but instead it seems like the opposite happens. I don't have a good answer for this problem. Here's my opinion:
If you notice, the same phenomenon happens with a marker and a whiteboard. So what I think the reason is, that due to adhesion forces among the chalk particles(or for that matter, between the particles/layers of the liquid ink), they tend to remain attached to each other and don't let go easily. So, when your duster removes the upper layers of the chalk particles, these particles exert an upward pulling force to the layer beneath them(The forces I've talked about a few lines above), because of which more chalk particles are removed from that area.
I have an argument to support my answer: If you use a cheap and rough chalk, this phenomenon doesn't take place because there are not enough upward forces in the chalk particles due to the powdery and rough nature of the chalk.
The following is multiple choice question (with options) to answer.
A piece of talc is rolled over on a black chalkboard and | [
"burns the board",
"wipes a spill",
"makes a streak",
"makes a dent"
] | C | when a mineral is rubbed on a streak plate , some of the material breaks off and forms a powder |
OpenBookQA | OpenBookQA-1847 | reproduction
Title: Why are so many species reproducing late this year? Hope this question is OK for this site, couldn't see where else to ask it.
We've spent a few days out in the countryside recently, and have been very surprised at how many species appear to have very young offspring so late in the season. I was always under the impression that the vast majority of animals and fish produced young in the spring (March/April).
For example, we saw tadpoles, fluffy (ie obviously very young) coots and weeny minnows. I would have expected that all of these would have been born/laid a good 3 or 4 months ago, and so would be more mature by now.
Caveat: We didn't do a scientific study, this is just a strong impression we got from days out in north west England. It's hard to say without more information, but one substantial possibility is that you are mistaken that species are reproducing late - that's a problem with anecdotal rather than scientific data!
Additionally, species you mention like the common coot can attempt multiple broods where the season is long enough. Wikipedia specifically mentions Britain:
Eurasian coots normally only have a single brood each year but in some areas such as Britain they will sometimes attempt a second brood
The same could be true for species of frogs/toads and fish, so without knowing specific species it can't be known whether these are species reproducing again or species reproducing late.
The following is multiple choice question (with options) to answer.
Reproduction produces | [
"bacteria",
"light",
"carrots",
"farrow"
] | D | reproduction produces offspring |
OpenBookQA | OpenBookQA-1848 | genetics, circadian-rhythms
Fig. 1. The SCN is entrained by environmental light captured by the retina in the eyes. Source: Neuroscience News.
The SCN is an intrinsic oscillator that governs sleep and wake timing, rhythms of temperature, hormones, mood and cognitive acuity etc. etc. These rhythms are entrained to 24 hours by the environmental light-dark cycle primarily via a subset of photosensitive retinal ganglion cells that project directly to the SCN (Fig. 1). Using hormones and neuronal signals, the SCN entrains peripheral clocks of similar molecular mechanism present in many tissues (Pagani et al., 2010).
In humans and other organisms, the timing of 24-hour behavior is governed by the period length of the circadian oscillator. This period is approximately, but not exactly, 24 hours long (circa diem), and ranges from 23.47–24.64 across people (23 hours 28 min to 24 hours 38 minutes) in laboratory conditions (Pagani et al., 2010).
Why is it circa diem and not exactly 24 hours? Note that the absolute length of a day depends on the definition used. For example, one complete rotation of the earth around its axis (the sidereal day) actually takes 23 hours, 56 minutes and 4.1 seconds. The solar day is 24 hours and is defined by the time it takes the sun to make an apparent circuit across the skies. More importantly, there is apparent solar time, sometimes called true solar time, which is determined by the daily apparent motion of the observed sun. It is based on the interval between two successive returns of the sun to the local meridian. The length of a solar day varies throughout the year, and the accumulated effect of these variations (equation of time) produces seasonal deviations of up to 16 minutes.
The following is multiple choice question (with options) to answer.
Cycles of day and night occur how often in a day? | [
"5 times",
"singular instances",
"forty times",
"once a year"
] | B | cycles of day and night occur once per day |
OpenBookQA | OpenBookQA-1849 | thermodynamics, phase-transition, states-of-matter
So in theory, you can have 100% ice that is at melting temperature. If you apply exactly the energy required for that amount of ice to transition to water, then you would have 100% water that is at the exact same temperature. If instead you only applied 50% of the energy required to melt that quantity of ice, then you would have a mixture of 50% ice and 50% water, still at the same temperature. (Of course in reality the temperature will not be perfectly even; you're much more likely to have ice at a range of temperatures from just below up to the melting point and water at a range of temperatures from the melting point to a bit above)
So there's a clear boundary in that each given "bit" of H2O is either water or ice, there's no state that is "in between ice and water" that is passed through on the way to melting the ice. The halfway point to melting a block of ice does not have all of the ice with "partially weakened bonds", or anything like that. But the transition of a large chunk of ice into water is a gradual process, not something that happens at a clear instant - more of the ice gradually undergoes the (sharp) transition to water as more energy is gradually added.
The following is multiple choice question (with options) to answer.
Ice made from which kind of water would melt when the others stay frozen? | [
"river water",
"swamp water",
"lake water",
"coastal water"
] | D | adding salt to a liquid decreases the melting point of that liquid |
OpenBookQA | OpenBookQA-1850 | thermodynamics, phase-transition, states-of-matter
So in theory, you can have 100% ice that is at melting temperature. If you apply exactly the energy required for that amount of ice to transition to water, then you would have 100% water that is at the exact same temperature. If instead you only applied 50% of the energy required to melt that quantity of ice, then you would have a mixture of 50% ice and 50% water, still at the same temperature. (Of course in reality the temperature will not be perfectly even; you're much more likely to have ice at a range of temperatures from just below up to the melting point and water at a range of temperatures from the melting point to a bit above)
So there's a clear boundary in that each given "bit" of H2O is either water or ice, there's no state that is "in between ice and water" that is passed through on the way to melting the ice. The halfway point to melting a block of ice does not have all of the ice with "partially weakened bonds", or anything like that. But the transition of a large chunk of ice into water is a gradual process, not something that happens at a clear instant - more of the ice gradually undergoes the (sharp) transition to water as more energy is gradually added.
The following is multiple choice question (with options) to answer.
If the temperature is 34 degrees Fahrenheit, what could be put on top of the icy sidewalk to turn the ice to liquid? | [
"sodium",
"dry leaves",
"pebbles",
"dry ice"
] | A | adding salt to a liquid decreases the melting point of that liquid |
OpenBookQA | OpenBookQA-1851 | java, object-oriented, state-machine
@Override
public Critter update(Ocean currentTimeStepSea){
int neighborSharkCount=0;
neighborSharkCount = Utility.countSharkAsNeighbor(this, currentTimeStepSea);
//Updating fish cell for current & next time step
if(neighborSharkCount ==1){
/*
* 4) If a cell contains a fish, and one of its neighbors is a shark, then the
* fish is eaten by a shark, and therefore disappears.
*
*/
return new Empty(this.getLocation().getX(),this.getLocation().getY());
}
else if(neighborSharkCount > 1){
/*
* 5) If a cell contains a fish, and two or more of its neighbors are sharks, then
* a new shark is born in that cell. Sharks are well-fed at birth; _after_ they
* are born, they can survive an additional starveTime time steps without eating.
*
*/
return new Shark(this.getLocation().getX(),this.getLocation().getY(),0);
}
else {
/*
* condition is (neighborSharkCount < 1)
* 3) If a cell contains a fish, and all of its neighbors are either empty or are
* other fish, then the fish stays where it is.
*/
return this;
}
}
}
/* Ocean.java */
package Project1;
/**
* The Ocean class defines an object that models an ocean full of sharks and
* fish.
* @author mohet01
*
*/
class Ocean {
/**
* Define any variables associated with an Ocean object here. These
* variables MUST be private.
*
*/
//width of an Ocean
private int width;
//height of an Ocean
private int height;
The following is multiple choice question (with options) to answer.
A shark is looking for a quick bite, so it | [
"eats some seeds",
"eats a sandbar",
"eats some seaweed",
"eats an eel"
] | D | carnivores are predators |
OpenBookQA | OpenBookQA-1852 | homework-and-exercises, newtonian-mechanics, energy
Title: How can iron be forged by a hand-powered hammer? If the compression strength of iron is 50 MPa, or 5 MPa at 1000C, how can it be forged by a falling hammer, weighing say 10 kg, 10x10 cm impact area -> 100N/0.01 m2 = 10 kPa? Having been a quasi-professional blacksmith for the past 13 years, I can provide a partial answer. Your calculation assumes that the pressure exerted by the hammer is just the weight of the hammer divided by the area of the hammer's face. In fact, the pressure should be calculated as the force due to deceleration of the hammer at the moment it strikes the workpiece, divided by the area of impact.
In order to get a sense of the deceleration, you can use the average depth of the impression left by a good hammer blow: around 2 mm. The speed of the hammer at the moment of impact is probably about the speed it would reach after falling freely for about 3 or 4 meters, or about 8 meters per second; and the hammer comes to a dead stop, or even rebounds, after traveling only a couple of millimeters subsequent to initial impact.
Also, a hammer blow is almost never perfectly flat. The hammer face is almost always is slightly tilted relative to the surface it hits, so all of the force due to that deceleration is initially concentrated in a few percent of the area of the hammer's face.
A seat-of-the-pants estimate, against which a properly calculated estimate should be compared, is that the hammer stops in 2 mm compared to a 4000 mm free fall, so the force exerted by the blow is on the order of 2000 times greater than the weight of the hammer. Add that to the slight tilt of the hammer face, and the force is probably more like 20,000 times greater than the weight of the hammer at the first moment of impact.
Another way to estimate the hammer's deceleration is to assume that the workpiece exerts a pressure equal to its yield strength, against the hammer. In the case of the slightly tilted hammer face, that pressure is initially exerted against only a small area so the deceleration is small; and the area increases as the impression size grows, so the deceleration increases. To calculate the deceleration vs time you would need to do an integral.
The following is multiple choice question (with options) to answer.
A person buys a cheap hammer and it breaks a month later. The person invests in an expensive hammer and | [
"it endures",
"died",
"baked it",
"ate it"
] | A | as the time a tool lasts increases , the number of tools discarded will decrease |
OpenBookQA | OpenBookQA-1853 | geometry, topology, elasticity, continuum-mechanics
Title: Twisting a string I may have some confusion about the twist and torsion of an elastic filament. The issue centers around this set-up.
I hold a cable in my hands, so that it forms a straight line. Keeping the endpoints clamped in my fingers, I move them closer together until they are right next to each other, so that the cable forms a circle. However, I can feel that there is significant twist-stress stored in the filament, so much so that for certain cables this is very hard to do. If I twist the endpoints as I move them together, though, I can feel that there is no stress, and the cable is clearly relaxed.
My question is, when is twist created in the first case? I have moved the endpoints in a straight line, and kept them clamped the whole time so they cannot rotate. It seems like the vanishing of the total twist should be topologically protected, but evidently not (or, the transformation I have performed on the filament somehow disturbed the topology). Where has my thinking gone wrong?
To be clear, my question is not about what, at the mechanical level, is causing the tension. I understand that as the material cross section rotates about the filament's tangent, stress is created. I'm more wondering how the cross section ends up rotating when I keep the endpoints clamped.
So I managed to solve this question on my own through some reading and calculations. The crux of my issue seems to be my belief that the total twist of the filament is topologically protected.
The following is multiple choice question (with options) to answer.
What prohibits cells from contorting into deformed shapes? | [
"helpful viruses help them retain their function",
"a prison cell wall contains them",
"the thin membrane which surrounds them",
"they have a Chilton's manual to guide them"
] | C | the cell membrane provides support for a cell |
OpenBookQA | OpenBookQA-1854 | optics, visible-light, reflection, refraction, lenses
Title: Why can't rainbows form at the start of a storm? I was recently at a park looking at the gorgeous scenery. I looked above and saw thick grey clouds covering up 3/4 of the sky. The sun's light is still visible for 1/4 of the sky, and it looks low enough to refract it's light through the clouds to form a rainbow. The rain started dripping slowly for 10 minutes. At five minutes I decided to take a panorama shot and ask the question, why won't a rainbow form at the start of a storm. I thought the place I was standing had the perfect condition for a rainbow to form.
Here is the panorama scene shot
There were a few rain drops pouring from the sky
The time I looked at the sky was 5:00 p.m., so the sun should be at an appropriate location.
But even if my scenario didn't give a rainbow, is this rare event still possible? The big deal with a rainbow is the angle between the sun and water droplets. The sun has to be behind you and the rainbow will occur at about 42 degrees away from the line from the sun through you. If everything lines up, you can have a rainbow at any time. (I've seen them on water spraying from a hose where things lined up just right.) This will work better when the sun in low in the sky, if the sun is too high in the sky the line from it to you goes into the ground. Since thunderstorms are often afternoon phenomenon, the sun is more likely to be low in the sky after the storm than before.
Looking at your panorama, it doesn't look like the sun was visible to you, so I wouldn't expect to see one.
The following is multiple choice question (with options) to answer.
A horse in a field under the summer sun was glistening wet even though it hadn't rained. | [
"the other horses were licking that horse",
"sweat glands released liquid to cool off the horse",
"sweat glands dried up",
"The horse needed a shower and was getting oily"
] | B | sweat is used for adjusting to hot temperatures by some animals |
OpenBookQA | OpenBookQA-1855 | thermodynamics, energy, temperature, estimation
Title: What would happen if a 10-kg cube of iron, at a temperature close to 0 kelvin, suddenly appeared in your living room? What would be the effect of placing an object that cold in an environment that warm? Would the room just get a little colder? Would it kill everyone in the room like some kind of cold bomb? What would happen?
Don't think about how the cube got there, or the air which it would displace. Nothing overly dramatic, though it would be cool to look at. The cube would very quickly become covered by a layer of nitrogen/oxygen ice as the air which came into contact with it froze. Further away, you'd see condensation of water vapor into wispy clouds, which would swirl around the block due to the air currents generated by the sudden pressure drop.
Other than that, as long as you aren't in immediate thermal contact with the block, you wouldn't notice much other than that the room cools down. Here's a video I took of a vacuum can that was just removed from a dewar of liquid helium at 4 kelvin. It's maybe 5 kg of copper, not 10 kg of lead, but I'd say that's close enough to get the idea.
You can see one of my coworkers climbing down into a pit below it; he had to be careful not to bump his head on it, which would have really ruined his day, but there was no fatal cold bomb :)
The following is multiple choice question (with options) to answer.
A person is going to freeze on a cold night. The person looks for something to ignite for a source of warmth, and chooses the best option, | [
"live frogs",
"old stones",
"dry switches",
"dry cheese"
] | C | burning wood is used to produce heat |
OpenBookQA | OpenBookQA-1856 | the-moon, moon-phases
Title: Red cresent moon Yesterday night i witnessed something very strange when i looked outside the window. I saw the moon (crescent) but it was dull red and right on the horizon ,which is strange considering that it is usually on the upper right of the night sky and white in colour. On further inspection with my binoculars i noticed it was lowering down until it was hidden by the mountain range (5km away) next to my building, this all occurred within a few minutes (about 5).
Tonight i saw the moon (crescent) had again returned to its normal position.
Please explain the cause for this, i'm completely baffled!
(Sorry for the poor wording, i'm not familiar with all the astronomical terms!) The dull red color has been due to atmospheric causes, like the reddish sun close to sunset. There hasn't been an astronomical reason for the reddish color.
A few days after New Moon moonset occurs short after sunset, so you won't see the Moon high over the horizon at those evenings. With each day the Moon is a little higher above the horizon after sunset. It's hence less close to the horizon at the same time of the day. Less close to the horizon means less atomospheric absorption/scattering responsible for the dull red color, assuming the same weather conditions.
At Full Moon the Moon is at the opposite side of the Sun relative to Earth. Moon is then rising shortly after sunset.
The following is multiple choice question (with options) to answer.
A person notes that the moon goes through various phases and eventually repeats these phases over the course of | [
"every other new month",
"about six more days",
"just over a month",
"just under a month"
] | D | a revolution of the moon around the Earth takes 1 month |
OpenBookQA | OpenBookQA-1857 | newtonian-mechanics, forces, friction, free-body-diagram, centrifugal-force
Title: Why can a car skid if you take a curve too quick? I've seen loads of cars that skid during a curve due to taking it with a high velocity. I can guess that it has to do with the grid with the road and maybe something to do with centifugal forces? On a flat road frictional forces can cause a car to change direction.
Static frictional forces have a maximum value, $\mu_{\rm S}\,N$ which depends on the coefficient of static friction $\mu_{\rm s}$ and the normal force $N$.
The force required make a mass $m$ travelling at a speed $v$ go around a circular corner $r$ is found by using Newton's second law, $F = mv^2/r$.
As long as $F \le \mu_{\rm S}\,N$ static frictional forces are large enough to make a car go round a corner.
However if the speed is too high $F > \mu_{\rm S}\,N$ and so the frictional force is not large enough and unless the radius $r$ of the trajectory of the car can be increased sufficient such that again $F \le \mu_{\rm S}\,N$ relative motion at the point of contact between the tyres and the road will occur, the car will skid and move along a straighter trajectory than before the skid.
Worse than that due a skid dynamic frictional forces will become involved and there forces are generally (much) less than the maximum static frictional forces with the transition from static friction to kinetic friction occurring over a very short span of time compared with the reaction time of the driver. Thus there can be a momentary loss of control until the driver reacts to the abrupt change in the type of frictional force which is acting.
Thus if you want to go round a corner at high speed the curvature of the corner must not be too high and you need to ensure that the static frictional forces are large enough by having wide tyres, softer rubber compound tyres (which feel like unset glue on F1 car tyres, lower pressure in the tyres and a good and dry road surface.
The following is multiple choice question (with options) to answer.
A vehicle rounds a corner and slips, squealing. The tires at that point experienced | [
"less friction",
"more friction",
"free falling",
"zero friction"
] | B | skidding causes friction |
OpenBookQA | OpenBookQA-1858 | optics, visible-light, reflection, refraction, lenses
Title: Why can't rainbows form at the start of a storm? I was recently at a park looking at the gorgeous scenery. I looked above and saw thick grey clouds covering up 3/4 of the sky. The sun's light is still visible for 1/4 of the sky, and it looks low enough to refract it's light through the clouds to form a rainbow. The rain started dripping slowly for 10 minutes. At five minutes I decided to take a panorama shot and ask the question, why won't a rainbow form at the start of a storm. I thought the place I was standing had the perfect condition for a rainbow to form.
Here is the panorama scene shot
There were a few rain drops pouring from the sky
The time I looked at the sky was 5:00 p.m., so the sun should be at an appropriate location.
But even if my scenario didn't give a rainbow, is this rare event still possible? The big deal with a rainbow is the angle between the sun and water droplets. The sun has to be behind you and the rainbow will occur at about 42 degrees away from the line from the sun through you. If everything lines up, you can have a rainbow at any time. (I've seen them on water spraying from a hose where things lined up just right.) This will work better when the sun in low in the sky, if the sun is too high in the sky the line from it to you goes into the ground. Since thunderstorms are often afternoon phenomenon, the sun is more likely to be low in the sky after the storm than before.
Looking at your panorama, it doesn't look like the sun was visible to you, so I wouldn't expect to see one.
The following is multiple choice question (with options) to answer.
A rainy day leaves a lot of moisture in the air and rainbows occur | [
"when light is burned",
"when light proceeds through",
"when light is black",
"when light is dim"
] | B | refracting sunlight causes light to split into different colors |
OpenBookQA | OpenBookQA-1859 | species-identification, botany
Title: Can you identify this (possibly waterstoring) plant? My son brought home a sapling, and after 4 years in a pot it is now about 30 cm or a foot high (from the "ground" to the top of the "stem"). It doesn't need a lot of water and can go weeks without being watered, in fact it seems to me as if it is storing water in the thicker upper part of its stem. When I water it "too much", new leaves start to grow. There are tiny "blossoms" along the stem, and every now and then small, dark brown, spherical seeds about 2 mm in diameter pop out from the "blossom" and are thrown across the room as far as a meter (about a yard) or two.
What plant is this?
I believe that it is not native to my European home but some kind of decorative plant imported and sold through a florist or imported privately, but I'm not sure. It is an Euphorbia leuconeura (Madagascar Jewel), which is native to Madagaskar. The leaves and the thick (waterstoring) stem with a narrow base is very typical.
The plant is cool in the sense that it easily produces seeds (also as potted) which it can shoot away from the plant. I've had it myself and you can sometimes hear seeds hitting the window or floor. Even if it is easy to grow and to reproduce it is actually considered threatened in its native habitat (IUCN Red-listed as Vulnerable) due to habitat loss
The flowers are very small and found directly on the stem, see below:
(picture from Wikipedia)
The following is multiple choice question (with options) to answer.
A plant will have difficulty growing larger if it is held away from | [
"corn",
"poison",
"ice",
"liquid"
] | D | a plants require water for to grow |
OpenBookQA | OpenBookQA-1860 | marine-biology, vestigial
Title: Modern Whales with Vestigial legs Myth? Is it a myth that modern whales have been found with hind legs sticking out of their sides and full formed tibias, fibias, and toe bones? I keep finding assertions, but no citations. For example, the wikipedia page has no citation for it.
http://en.wikipedia.org/wiki/Whales#Appendages The link you give doesn't mention limbs sticking out of the body wall, but only vestigial hind limb elements. Many whales do retain pelves and femora, as this page at the Bergen Museum shows. Given the variation in limb development across vertebrates, it would not be surprising to find more distal elements (but I would be very surprised if they extended past the body wall).
The following is multiple choice question (with options) to answer.
Jackrabbits' hind legs are | [
"weak",
"stubby",
"elongated",
"short"
] | C | long ears are used for releasing heat by a jackrabbit |
OpenBookQA | OpenBookQA-1861 | entomology, ethology, parasitology, ant, parasitism
Title: The emergence of Phengaris butterflies from ant nests The butterflies of the Phengaris genus (also known as Maculinea) are known to be brood parasitic. During the fourth instar, the caterpillars leave their food plant and mimic ant larvae, causing the ants to take them back to their nest as if they were ant larvae that had escaped.
While in the nest, the caterpillars mimic ant larvae by means both of surface chemicals and acoustic mimickry (including, I understand it, mimicking sounds made by queens!) After pupating, the pupa continues to engage in acoustic mimickry, although I can't find any reference to whether it does (or even could!) engage in continued chemical mimickry.
But I can't find anything in the literature regarding the adult butterfly's emergence from the pupa and exit from the ant nest. A non-academic book and some web pages claim that the alcon blue (Phengaris alcon) and mountain alcon blue (Phengaris rebeli) adults are no longer engaged in any form of mimickry at this point, and may be attacked by the ants. These accounts differ as to how likely an attack is, how much danger the butterfly is in, and the level of protection afforded by the butterfly scales.
The webpages I mention belong to a University of Copenhagen researcher (Dr. David Nash) who has published work in this field. This suggests that the claim is probably correct.
That said, none of the peer-reviewed publications coauthored by him appear to mention it, and each of the two webpages creates a different impression as to the level of danger involved:
"If an ant tries to bite the butterfly it will only get a mouthful of scales." states one, suggesting that there is little the ants can do to harm or hinder the butterfly. But the other states "The adult has to get out of the ant nest quickly to prevent the ants killing it."
The book is written by someone else. It cites three papers, which do discuss the larvae/pupae and ants. But none of these have any information regarding this specific topic.
The following is multiple choice question (with options) to answer.
If an anteater eats an ant, where is that ant contained? | [
"outside the anteater",
"inside the anteater",
"in the sky",
"underground"
] | B | if something absorbs something else then that something will contain that something else |
OpenBookQA | OpenBookQA-1862 | thermodynamics, energy-conservation, conventions
$$T_C = \frac{\mathrm{COP}_\mathrm{given}}{1 + \mathrm{COP}_\mathrm{given}} T_H$$
The absolute minimum temperature achievable with a COP of 3.28 and outdoor temperature of, say, $300\ \mathrm{K}$ is thus $230\ \mathrm{K}$, well below freezing. However, in practice, it will not be possible to reach this temperature because the ideal COP assumes the only point of heat flow is the machine itself, and perfect utilization of the energy input - at the calculated point, the heat going out from the machine will equal that coming back in through it due to the temperature gradient, a dynamic equilibrium. In reality, heat flow from the outdoors and the rest of the building through imperfectly-insulating walls, doors, and other portals will be adding additional heat back into the room. Moreover, a realistic machine will also waste input energy (e.g. electrical resistance in the wires, friction in the machine components, etc.), converting it into heat (not pumping heat) and hence acting to an extent as a heater for the room.
But the point is that, as long as the room temperature desired is above this temperature, then it is not a violation of the second law to cool to that desired temperature.
The following is multiple choice question (with options) to answer.
A kitten in a hot environment has little to zero ability to | [
"take a short nap",
"be very warmed up",
"adjust its internal temperature",
"lap up some water"
] | C | a mammal is warm-blooded |
OpenBookQA | OpenBookQA-1863 | 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.
Squirrels eat a variety of foods including | [
"beef",
"tender leaf buds",
"pork",
"cotton candy"
] | B | squirrels eat edible plants |
OpenBookQA | OpenBookQA-1864 | electrostatics
Title: Inducing positive charge on a Sphere(Metallic) Sorry if this question is asked already. I want to know that while inducing positive charge on a neutral body, at the time of earthing why the electrons move out so easily from the neutral body to the ground.I wonder Is it that easy to remove the electrons from a body. And aren't there a lots of electrons already in the ground so that if electrons are moving through earthing to ground will be repelled back to the body. Hope I will get a reply soon Thanks! The potential of earth is consider to be zero so charge can easily flow into earth as charge flow from body at higher potential to lower potential.Also the earth is so large that the addition of electrons dont increase the charge of earth they will simply lost in the earth.
The following is multiple choice question (with options) to answer.
join a negative and a positive charge through a rare metal in a gas filled globe is known as | [
"led",
"High Pressure Sodium",
"incandescence",
"compact florescence"
] | C | an incandescent light bulb converts electricity into heat by sending electricity through a filament |
OpenBookQA | OpenBookQA-1865 | electromagnetism, electricity, electric-current
In short, the conducting electrons push on the surface charges, and these push the conductor via EM and possibly via non-EM forces.
When a conducting moving electron (or "element of conducting charge" in the macroscopic theory) suddenly starts experiencing an external magnetic force, it begins to change its velocity. Thus the average conduction velocity there changes direction, from being in direction of the total electric field, to a slightly different direction, due to presence of the external magnetic field. This happens to all conducting electrons experiencing the magnetic field there.
However, and this is the main point, the affected conducting electrons near the surface can't just move in the new direction out of the conductor; they are prevented from doing so by constraint forces due to the conductor acting back on the surface electrons (unless there is a field emission or other kind of charge emission which overcomes these constraint forces).
In other words, in general, the electrons can only move freely inside and on the surface, but can't jump out of the conductor into the vacuum. Electrons clump on some conductor surface patches (such patches become negative), and they are lacking on other surface patches (such patches become positive).
The constraint force on the surface charge is a net result of all microscopic EM interactions (and possibly non-EM interactions) there between the conducting electrons and the rest. These interactions create something like a steep potential barrier on the conductor surface, which the electron can overcome only if it has high enough energy, or some external force is strong enough. One way to understand this constraint force is to think of what happens when a charged test particle approaches a large body made of many positive and negative particles. As the test particle approaches the body, the attracting force increases (due to polarization of the neutral body), and becomes very high when the test particle is on the surface, as close to the other particles as is the typical particles separation distance in solid body. When the test particle continues and comes inside, the force as function of position becomes oscillatory on a very short length scale, which has similar effect on macroscopic conduction as being zero. That's why we see effects of these interactions and the macroscopic constraint force only on the surface.
The following is multiple choice question (with options) to answer.
insulation for the purposes of moving electrons involves | [
"conductor wrapped wire",
"insulator wrapped insulator",
"non coated metal",
"insulation encompassed wire"
] | D | electrical insulation requires wrapping a conductor in an insulator |
OpenBookQA | OpenBookQA-1866 | the-moon, moon-phases
Because the full Moon happens when the Moon and Sun are on opposite sides of the Earth, the Moon is most directly opposite the Sun near the Spring and fall equinox. That makes the Harvest Moon (full moon closest to the fall equinox) and the full Moon closest to the spring equinox, more directly opposite the sun, so they reflect slightly more light to the Earth. This effect basically just makes the Moon a bit rounder than other full moons. If you've ever noticed, mid summer or mid winter, the full moon can appear fatter than it is tall. That's not an illusion, it's due to the 5 degree inclination.
This effect on overall brightness is small, but your eyes might be noticing a rounder moon and seeing it as brighter. It's theoretically possible.
This year's largest moon was in March, so today's full moon is actually smaller than average. Astronomical measurements will always say that the closest full moon is the brightest one because it's larger in the sky and it reflects more total light towards the Earth, but apparent brightness to your eyes might have little to do with it's increasing or decreasing angular diameter and likely has more to do with how clear the night sky is. Our eyes can fool us. It's possible that the smaller moon appears brighter even though it reflects less light because it also scatters less light across the rest of the sky, similar to how a smaller flashlight might appear brighter if you stare into it, compared to a flashlight with a wider opening that gives off more total light.
A clear night is probably the best explanation. I'd pick that over smaller angular diameter or greater roundness. On a clear night, the Full Moon can appear brighter because less light gets scattered around it, making it look bright against a sky that's slightly darker, but you don't notice the sky's variation.
The full moon is also higher in the sky in winter, because it moves mostly opposite the sun. Being higher in the sky mans there's less atmosphere between the Moon and you. Directly overhead should be brighter than at an angle to a person viewing from Earth.
Edit
doing some looking I came across this website. It claims:
The following is multiple choice question (with options) to answer.
A full moon is visible | [
"bimonthly",
"biweekly",
"every two months",
"every four weeks"
] | D | each of the moon 's phases usually occurs once per month |
OpenBookQA | OpenBookQA-1867 | exoplanet
It's probably possible to have volcanic eruptions even though dozens or maybe even hundreds of miles of exotic ice because the heat has to go somewhere, eventually, assing it's likely to build up over time, so either by circulation of eruption, the heat has push through at some point. This even happens on so called "dead" planets like Mars or even the Moon. Mars still has the occasional volcanic eruption, just not very often.
But water worlds certainly can have plate tectonics. There's nothing in the water that would prevent it from happening. Plate Tectonics is, as I understand it, primarily a factor of the size of the planet. Gas planets - different story, but planets with a hard surface, Earth sized, a tiny bit smaller to a fair bit but not much bigger are good candidates for plate tectonics (I think). There's some debate on how large, I think, still going on. But I remember reading that ocean/water worlds might even be more likely to have plate tectonics. Plate tectonics is definitely something we'd look for if we ever get a close enough look at other planets in different solar-systems (exoplanets).
Just my thoughts on this. Not meant to be complete or definitive.
The following is multiple choice question (with options) to answer.
Due to plates gliding over our planet's mantle, why is Vancouver likely to be destroyed? | [
"it sits on an active fault line",
"it's located in Canada",
"it has French people",
"the Pacific Ocean is only half as blue as the Atlantic"
] | A | a tectonic plate moves along a fault line |
OpenBookQA | OpenBookQA-1868 | python, beginner, python-3.x
while True:
self.fertilizer = int(input("Please enter the amount of fertilizer (scale 0-10): "))
if self.fertilizer not in range(11):
print("***NOT A VALID AMOUNT***")
continue
if self.fertilizer == self.Plants.preferred_fertilizer:
self.fertilizer_score = 10
break
elif self.Plants.preferred_fertilizer - 2 <= self.fertilizer <= self.Plants.preferred_fertilizer + 2:
self.fertilizer_score = 7
break
else:
self.fertilizer_score = 4
break
# Automated weed removal: random score
count = 0
while self.weed == True:
x = 1* random.random()
count += 1
if x < 0.3:
self.weed == False
print("You have removed the weeds", count, "times to help the plant grow. Good job!\n")
break
if count <= 3:
self.weed_score = 10
else:
self.weed_score = 5
# Calculate probability of fruit growth. Weight of parameters: water 30%, fertilizer 30%, soil type 10%, - user selection
# weed 20%, temperature 10% - random
self.probability = 0
if self.Environment.soil_type == self.Plants.preferred_soil:
self.probability += random.uniform(0.7, 0.9) * 0.1
else:
self.probability += random.uniform(0.3, 0.5) * 0.1
if self.Environment.temp_return == self.Plants.preferred_temp:
self.probability += random.uniform(0.7, 0.9) * 0.1
else:
self.probability += random.uniform(0.3, 0.5) * 0.1
The following is multiple choice question (with options) to answer.
What are some of the risks of using fertilizer? | [
"Making potatoes",
"Helping food grow",
"Fertilizing the crops",
"Damaging the planet"
] | D | fertilizers are a source of pollution |
OpenBookQA | OpenBookQA-1869 | conductors, power
Title: Hollow conductor for transmission line A hollow conductor can transfer almost the same current when compared to a solid conductor with less material requirement due to the skin effect. But still, we use solid stranded conductors for a transmission line. Why is it so? The high power lines often use multiple cables with spacers. The thickness of the layer of conductive strands in each cable approximates the skin depth. So, they achieve the efficient use of material you seek by different means.
The following is multiple choice question (with options) to answer.
What could be used as a conductor? | [
"a cat",
"A penny",
"a cloud",
"wood"
] | B | sending electricity through a conductor causes electric current to flow through that conductor |
OpenBookQA | OpenBookQA-1870 | agriculture
The primary cereals for making bread are wheat and rye, while barley and oats may be mixed in. Historically significant portions of the rural population of Europe were sustained by cereal-based food in the form of gruel and porridge rather than by bread, especially prior to the introduction of the potato. Barley can be consumed in the form of pearl barley and groats and oats in the form of oatmeal. Especially in cool and humid climates not very suitable for cultivating wheat and rye, oats were once commonly cultivated and consumed. When Samuel Johnson wrote his dictionary, he famously defined oats as: "A grain which in England is generally given to horses, but in Scotland supports the people." A major historical and modern use of barley has been as malted barley, the main ingredient in beer brewing.
In the case of Finland it is interesting to note how late the transition from slash-and-burn agriculture to the use of permanent fields occurred. According to Teija Alenius, Environmental change and anthropogenic impact on lake sediments during the Holocene in the Finnish − Karelian inland area, Ph.D. thesis, University of Helsinki, 2007 (online)
The following is multiple choice question (with options) to answer.
A farmer needs to change up his crops. He has planted grains for the last five years. He plants something different this year, so his crop is probably | [
"oats",
"rice",
"watermelon",
"grain"
] | C | crop rotation is when different crops are planted on a field in different years |
OpenBookQA | OpenBookQA-1871 | zoology, species-identification, ornithology, behaviour
Title: What is this crow eating, and is it a common part of the corvid diet? Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:
Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.
What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird? Crows are omnivorous, and will eat almost anything they find or can kill.
In this case the prey looks like a Yellow-Shafted Flicker.
The following is multiple choice question (with options) to answer.
A dart frog is eaten by a pelican, who promptly | [
"passes away",
"wakes up",
"eats birds",
"flies home"
] | A | poison causes harm to living things |
OpenBookQA | OpenBookQA-1872 | evolution, psychology, sociobiology
Title: Female preference for males who are already in a relationship A common saying is that women are generally more attracted towards men who are already in a relationship, and this phenomena does seem to have its own place in popular culture that is not matched by a corresponding male preference for women who are already in a relationship.
From an intuitive viewpoint I think it would make sense from the woman's viewpoint in an system of information economics where the fact that a male is engaged in a successful relationship with another female, or several other females, might provide extra and positive information about the evolutionary value of the male.
But how about the possibility for a male to use the same trick?
Is there any empirical evidence for this behaviour at all either in humans or in other species, or is this just a cultural artefact in some human societies? If there is empirical support, is there a consensus on the plausible evolutionary pathways involved here? This is a widely researched topic in the overlap between social sciences and evolutionary biology. Evolution has become very influential in understanding human interaction and preferences.
This chapter from "The Adapted Mind : Evolutionary Psychology and the Generation of Culture" will give you an idea of how all this plays out in the big picture - its a fairly comprehensive review of many factors considered in human mate choice. The study may be psychological, but the logic is derived from biology these days. (stackexchange won't let me link to google books - you can search for the title and look at chapter 6).
Evolutionary tendencies will favor more successful offspring. But for people it includes not only the genetic qualities of the mate (appearance, height, disease resistance, health) but also social qualities (how reliable or willing a mate is to support offspring).
First off you can see that there are many many factors which women take into consideration in their preferences. Its commonly said they are more complex than men, but that's another question. You have to take a range of factors holistically including the social environment.
I can't find this particular issue addressed in the literature, but I think that it might be attractive to women in some social settings. If there is a lot competition for 'quality' mates or resources for instance - if you have very few secure males or pessimistic females might create pressure which would cause females to prefer males which were successful.
The following is multiple choice question (with options) to answer.
Preferences tend to be | [
"genetic",
"learned attributes",
"naturally occurring",
"taught"
] | B | preferences are generally learned characteristics |
OpenBookQA | OpenBookQA-1873 | 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.
To be a friend of the environment | [
"buy products that can be reused",
"drive a gas guzzling car",
"throw aluminum cans in the trash",
"litter in public parks"
] | A | recycling has a positive impact on the environment |
OpenBookQA | OpenBookQA-1874 | reproduction
Title: Can different kinds of dogs mate? This was inspired by a show in which two different kinds of dogs, who were neighbors, "dated," in order to bring their human neighbors together. This is a theme seen in Disney's "101 Dalmations" or "The Lady and the Tramp."
Can dogs of similar sizes, say Rotweilers or pitbulls actually interbreed? Can any of them mate with say, wolves? And under what circumances?
(I am "encouraged" by the fact that horses and donkeys can produce mules, and lions and tigers can produce "liger" or "tigons." Also of note is that dogs are of the same species as wolves, and "domestic dogs" are actually a subspecies.) Yes, the vast majority of dogs out there are not pure bred. They are therefore a cross between two breeds. Consider cockapoos for example. The offsprings of a Cocker Spaniel and a poodle is called a cockapoo.
The following is multiple choice question (with options) to answer.
Dogs | [
"are born with teeth",
"leave their young to fend for themselves like turtle babies",
"provide direct sustenance to their newborn puppies",
"lay eggs to sit on"
] | C | a mammal usually nurses its offspring |
OpenBookQA | OpenBookQA-1875 | newtonian-mechanics, everyday-life, collision, spring
But if you pull the small block away from the large block slowly, then the large block will follow the small block, while the spring doesn't stretch terribly much. In this case, the low acceleration of the large mass takes place over a longer time, and so it can move more while the force is being exerted on it. This is the equivalent of going over a bump/pothole at low speed; since the wheels move up or down relatively slowly, the frame of the car will follow them. If you go over a bump at low speed, this means that the frame will follow the wheels (which follow the road surface), rather than moving in something resembling a straight line and possibly hitting the road surface.
The following is multiple choice question (with options) to answer.
When you start to drive away from your house, the longer you drive, your house will eventually look | [
"dead",
"bigger",
"smaller",
"icier"
] | C | as distance to an object increases , that object will appear smaller |
OpenBookQA | OpenBookQA-1876 | species-identification
Title: Identification of insect I am trying to identify this insect on a hibiscus plant. Google googles is unable to identify it. It's a Japanese Beetle Popillia japonica - they are invasive in most of North America and some of Europe now.
https://en.wikipedia.org/wiki/Japanese_beetle
They are spreading rapidly west in the United States and many areas are reporting the largest numbers ever observed, for example:
http://www.wisconsinrapidstribune.com/story/life/2017/07/19/japanese-beetles-invade-central-wisconsin/490140001/
http://www.omaha.com/living/japanese-beetle-swarms-are-worse-than-ever-this-year-and/article_77257d36-6c28-11e7-839a-877ff3c8538b.html
For control around your plants, it is recommended to manually remove them; brushing or placing them in water with some dish soap works well. They tend to congregate with other individuals of the species, so if you take them off your plants that will tend to limit the numbers that join them. However, they likely do the most damage to gardens etc as larvae, and there doesn't seem to be a good, specific way to control them at that stage.
The following is multiple choice question (with options) to answer.
A bee will seek out a plant that advertises its | [
"bright stem",
"tantalizing liquid",
"nice friend",
"green leaves"
] | B | nectar is used for attracting pollinators by plants |
OpenBookQA | OpenBookQA-1877 | optics, everyday-life, polarization, vision
Here's the main issue with sunglasses. Longer wavelength UV will cause sunburn of the retina at even low but constant levels. Shorter wavelength light begets phototoxicity: this arises when the light is energetic enough (photons of short enough wavelength) to knock outer shell electrons off and bring about chemical change and thus real cellular damage (even cellular nuclear damage, with its attendant cancer risk) within the retina. You wear sunglasses to avoid the painful longer UV wavelength sunburn that you'll inevitably get at chronic exposure to even low level sunlight and avoid the medium and long term risks of cataracts or worse (even eye cancer) that arise from chronic exposure to even low levels of shorter wavelength UV. The factor of one half attenuation I cited above for polarising filters does very little if any good in mitigating these risks.
The following is multiple choice question (with options) to answer.
What can you use to protect your eyes from the sun? | [
"shoes",
"pants",
"nails",
"sheet of paper"
] | D | looking directly at an eclipse of the Sun causes harm to the eyes |
OpenBookQA | OpenBookQA-1878 | thermodynamics, temperature, everyday-life, phase-transition, humidity
Title: Steam from a cup of coffee I observed that, in winter there is more visible steam from a cup of coffee than in summer. Is there any phenomenon taking place here. The amount of water that air can take up before the water creates fog or visible steam depends on temperature. The colder the air, the less water it needs to create fog/steam. It is the same principle when hot air rises, for example when pushed up a mountain and then it starts to cool down drastically --> It will rain.
For more have a look at: Relative humidity in https://en.wikipedia.org/wiki/Humidity
The following is multiple choice question (with options) to answer.
Fog is formed by water vapor condensing in what? | [
"plants",
"air heads",
"empty space",
"animals"
] | C | fog is formed by water vapor condensing in the air |
OpenBookQA | OpenBookQA-1879 | aerodynamics
Title: How do eagles fly slowly for a long time? Eagles fly slowly for a long time.
Many other species fly faster and move their wings faster. But eagles keep their wings steady, and move only their tail.
How do they move slowly in the air, without falling down?
Can this eagle flying technique be used in aviation? How does they move slowly in air, without falling down?
One possibility is soaring using a ridge lift - typically a situation when the wind is approx. perpendicular to a mountain ridge. The air is lifted at the front side of the ridge and an eagle can soar in the lifting air stream. This can also work without the wind,
Which is a situation of thermal flying. Typically, the ground is heated by the Sun, the air layer just above the ground is heated by conduction and at some moment it forms a kind of bubble that starts to rise. This bubble is usually long, resembling a column and lasts until the warm air is depleted. The situation can repeat (this behavior is called an interval). If a ridge is oriented south, then the Sun can create a thermal wind (intervals) that enables a bird to soar.
Can we use eagle's flying technic for flights? Yes, however, man will never be that good.
soaring: https://www.youtube.com/watch?v=63qJn9HrB7E
thermal flight: https://www.youtube.com/watch?v=KXqTCM0-zXQ
Edit: Just for completness - there exists also a wave soaring, that is reachable for gliders and maybe for hangliders, probably not possible for birds and paragliders - see pictures here : http://www.ssa.org/GliderLiftSources
The following is multiple choice question (with options) to answer.
A Bald Eagle's ability to build it's nest is | [
"observed trough observation of others",
"a biological trait passed down in it's genes",
"learned through trial and error",
"learned from watching its mom"
] | B | An example of an inherited behavior is a bird building a nest |
OpenBookQA | OpenBookQA-1880 | raspberry-pi
ACC = AutonomousCruiseControl()
# range second parameter is numbers to generate not the right boundary
for i in range(0,8):
ACC.front_sonar.readings = readings[i]
print("{}. reading: {}".format(i, ACC.read_front_sonar()))
print("{}. FOS: {}".format(i, ACC.get_front_object_status()))
ACC.drive()
if __name__ == '__main__':
main()
acc.py
#!/usr/bin/env python3
# coding=UTF-8
from navigation.hcsr04 import Hcsr04
from navigation.servo import Servo
from random import randint
class AutonomousCruiseControl:
"""helping to steer a robot trough obstacles"""
def __init__(self, object_colision_range=None, front_sonar_angles=None):
# initiate sensors
self.front_sonar = Hcsr04()
self.front_sonar_servo = Servo()
self.collision_distance = 20
if object_colision_range is None:
self.object_colision_range = [10, 15, 20, 15, 10]
else:
self.object_colision_range = object_colision_range
if front_sonar_angles is None:
self.front_sonar_angles = [0, 45, 90, 135, 180]
else:
self.front_sonar_angles = front_sonar_angles
self.front_sonar_distances = [200, 200, 200, 200, 200]
self.read_front_sonar()
print(self.front_sonar_distances)
self.front_object_status = [0, 0, 0, 0, 0]
The following is multiple choice question (with options) to answer.
Sonar is used to find an objects what? | [
"locale",
"elements",
"minerals",
"mass"
] | A | sonar is used to find the location of an object |
OpenBookQA | OpenBookQA-1881 | 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 snowy mountain is a good place to | [
"watch the sports team the Colorado Avalanches",
"play a strenuous game of beach ball",
"go downhill with wooden planks attached to boots",
"dive into an Olympic-sized swimming pool"
] | C | snowy means a large amount of snow |
OpenBookQA | OpenBookQA-1882 | geology, geography, satellite-oddities
Title: Round structure in southern United States Assuming here might be someone who knows something about this, I wanted to ask what is behind this round structure I have spotted today on Google Earth:
There seems to be a large (~200 km), nearly perfect half-circle covering the states of Alabama, Mississippi and Tennessee. How could this regular structure possibly originate? I did some research on the web, but could not find anything. It looks a bit like an impact crater, but there is none listed in this location and especially of this large size. So how did this structure emerge? This is a sedimentary sequence representing the shoreline of a Cretaceous-Paleogene inland sea, the Western Interior Seaway. You can look at the sequence of sediments laid down in the USGS Geological Map of North America. I recommend downloading the Southern Sheet in high resolution and the Explanation Sheet to explain what's going on.
The land use pattern as seen by other people answering this question is actually putting the effect in front of the cause; due to the nature of these sediments being a positive influence on the fertility of the land, it is more likely to be used for farming.
The following is multiple choice question (with options) to answer.
This two letter company had a structure in the Gulf of Mexico that exploded causing coastal animals to be coated in | [
"dirt",
"foam",
"natural gas",
"oil"
] | D | offshore oil platforms might cause oil to leak into the water |
OpenBookQA | OpenBookQA-1883 | optics, everyday-life, refraction, order-of-magnitude, estimation
So my first question is: what's wrong? Why are there mirages when this model predicts that there are not?
My second is: why do we see them only when it's hot? This model depends only weakly on absolute temperature, and hot absolute temperatures actually decrease the effect. Evidently, there are only high temperature gradients on hot days, by why should that be? A temperature gradient over the asphalt comes from sun heating the asphalt directly more than it heats the air. Shouldn't that happen on cold days as well as on hot days? I have not done the math but would expect that the radiation from the asphalt as $T^4$ will favor larger gradients for higher temperatures. I have the impression that air goes something like $T^6$, so even conduction energy transferred will have larger gradients the hotter it is. Your g is temperature dependent I guess.
Edit in response to edit of question.
Shouldn't that happen on cold days as well as on hot days?
I am copying from the comments below:
if you do the calculation of black body, asphalt at $40^\circ \mathrm{C}$ radiates $547\mathrm{watts}/\mathrm{m}^2$. At $41^\circ\mathrm{C}$ 551, i.e. difference $4\mathrm{watts}/\mathrm{m}^2$, whereas at $50^\circ\mathrm{C}$ 617 and at $51^\circ\mathrm{C}$ 628, i.e. $11\mathrm{Watts}/\mathrm{m}^2 \Delta T$. that is what I mean by g is temperature dependent. If there is convection the asphalt remains cooler and the equilibrium between heating from incoming radiation and cooling from black body is lower.
The following is multiple choice question (with options) to answer.
Which might need warm asphalt to help regulate its body temperature? | [
"whales",
"dolphins",
"rattlesnakes",
"squid"
] | C | a reptile is cold-blooded |
OpenBookQA | OpenBookQA-1884 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
Woody organisms that produce plants like oak tree seeds and leaves are a source of energy for | [
"decomposed waste",
"consumers like deer",
"other producers",
"producer organisms"
] | B | a producer is a source of energy for consumers |
OpenBookQA | OpenBookQA-1885 | 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.
Scraping the side of a cliff may result in | [
"ice",
"snow",
"sand",
"wood chips"
] | C | scraping an object may cause small particles to break off of that object |
OpenBookQA | OpenBookQA-1886 | This will result in an answer that that does not violate any of the stated constraints.
We have 3 fishes in each tank.
We have 7 tanks in sector Gamma.
We have 5 sharks in sector Gamma.
However, this seems like a bit of kludge. The proper way go about it is represent the number of sharks in the each sector as binary array, with only one value set to 1.
# Number of sharks in each sector
@variable(m, s[i=1:3,j=1:7], Bin)
We will have to modify our constraint block accordingly
@constraints m begin
# Constraint 2
sharks[i=1:3], sum(s[i,:]) == 1
u_sharks[j=1:7], sum(s[:,j]) <=1 # uniquness
# Constraint 4
sum(nt) <= 13
# Constraint 5
s[1,2] == 1
nt[1] == 4
# Constraint 6
s[2,4] == 1
nt[2] == 2
end
We invent a new variable array st to capture the number of sharks in each sector. This simply obtained by multiplying the binary array by the vector $$[1,2,\ldots,7]^\top$$
@variable(m,st[i=1:3],Int)
@constraint(m, st.==s*collect(1:7))
We rewrite our last constraint as
# Constraints 1 & 3
@NLconstraint(m, st[1]+st[2]+st[3]+n*(nt[1]+nt[2]+nt[3]) == 50)
After the model has been solved, we extract our output for the number of sharks.
sharks_in_each_sector=getvalue(st)
…and we get the correct output.
This problem might have been an overkill for using a full blown mixed integer non-linear optimizer. It can be solved by a simple table as shown in the video. However, we might not alway find ourselves in such a fortunate position. We could have also use mixed integer quadratic programming solver such as Gurobi which would be more efficient for that sort of problem. Given the small problem size, efficiency hardly matters here.
06/12/17
The following is multiple choice question (with options) to answer.
A shark is hunting prey, and the prey is an underwater creature with eight arms. The prey escapes by | [
"flying away",
"releasing dark fluid",
"crying loudly",
"being friendly"
] | B | octopuses releasing ink into the water causes predators to have difficulty seeing the octopus |
OpenBookQA | OpenBookQA-1887 | homework-and-exercises, radiation
Title: light beams of the sun
We receive sunlight on earth surface. What type of light beams are these?
Random/Parallel/Converging/Diverging
I think it should be Diverging as Sun is radiating these beams away. But in one book, answer is given as Random, in another it's Parallel. It is difficult to answer this question. An EM wave is generated by vibrating charges and nuclear reactions. Sun is full of vibrating charges and nuclear fusions. Because of this full range of frequencies are emitted. At distances close to sun we observe the directions of waves to be random. But at far away distances the direction of waves seem parallel. Since only parallel waves can have constant separation between them. Converging and diverging waves become distant at longer distances.
The following is multiple choice question (with options) to answer.
Sunlight is a source of light from what? | [
"lamps",
"lightbulbs",
"local star",
"star actor"
] | C | the sun is a source of light called sunlight |
OpenBookQA | OpenBookQA-1888 | fossils, drilling
Title: What would people drilling through Mount Everest find? I am interested in knowing what kind of fossils we would find if we were to drill horizontally through the mountain and what we would find if we were to drill vertically. Would we find anything interesting other than the fossils? Looks like some basic hints are necessary (as a complement to @AndyM's answer):
stratigraphy usually goes from younger to older when going down.
there'll be little chance to find any macrofossils in rocks that formed before sufficiently complex life was around.
there'll be little chance to find fossils in rocks that underwent metamorphism, that is have been in pressure/temperature regimes that aren't conducive for their preservation, even if they initially were present in the pre existing rocks.
'trace fossils' are not small remains of fossils but fossilized traces ('footprints'). Very rare thing.
it may be possible to find fossils in overlaying, younger sediments that formed during or after the uplift or were trapped or transported in depressions, but that's not the point of the question I think.
So, below the uppermost formations around the summit you'll likely find nothing of interest in the sense of the question when drilling down.
Will provide sources on specificically focussed request, but this isn't top notch geoscience.
The following is multiple choice question (with options) to answer.
Fossils fuels can be anything like | [
"buildings",
"cars",
"silverware",
"ancient poo"
] | D | fossil fuels are formed by dead organisms over time |
OpenBookQA | OpenBookQA-1889 | meteorology, wind
Title: Why does wind blow offshore in the morning? I live in San Diego, CA, and surfers capitalize on dawn hours because the offshore (seaward) winds help "hold up" the waves, i.e. prevent them from crashing before the surfer gets to ride it a while.
I'm only a beginner, but when I went to Korea, I met surfers from Santa Cruz, CA and Tianjin, China, who said it's the same everywhere.
Why does this happen? The phenomenon you describe is denoted as a land breeze. It is caused by a difference between the sea surface temperature and the land surface temperature.
Surface Temperature
During day time the surface temperature at land rises faster than the sea surface temperature, whereas during night time the land surface cools faster than the sea surfaces. As a result, the sea surface temperature is higher than the land surface temperature in the morning.
Formation of the Breeze
The sea surface heats the air above the sea stronger than the land surface does with the air above land. The warmer air masses above the sea rise to higher altitudes yielding a low pressure region. As a result, the colder air masses from above the land 'travel' to the low pressure region above the sea. This 'traveling' of air masses is wind: wind, which blows from the land to the sea.
Here is a nice Figure from Wikimedia Commons describing the sea breeze (A, evening/afternoon) and the land breeze (B, morning). The Figure was provided by Jesús Gómez Fernández.
Shower Curtain Example
If you shower in a shower with a shower curtain, you might experience that the lower end of the curtain moves towards your legs. The physical processes are similar: The warm shower water heats the air within the shower. The warm air rises which causes a low pressure region at the bottom of the shower. The air is colder at the bottom of the room outside the shower which leads to a high pressure system. The air from the high pressure system (bottom outside the shower) 'tries' to flow towards the low pressure system (bottom inside the shower) which moves the bottom end of the curtain towards you.
This example works only if the room temperature in the bathroom outside the shower is not too warm/hot.
The following is multiple choice question (with options) to answer.
When warm winds blow across an area from off of the sea, | [
"snow is gone",
"beaches are littered",
"storms are imminent",
"clouds are scarce"
] | C | a warm front causes cloudy and rainy weather |
OpenBookQA | OpenBookQA-1890 | electricity, electric-current, earth, electrical-resistance, estimation
Title: If the Earth is a good conductor of electricity, why don't people get electrocuted every time they touch the Earth? Since the Earth is a good conductor of electricity, is it safe to assume that any charge that flows down to the Earth must be redistributed into the Earth in and along all directions?
Does this also mean that if I release a million amperes of current into the Earth, every living entity walking barefooted should immediately die? Electricity isn't a gas that expands out to shock anything in contact with it. Electricity is a flow from high voltage to low voltage. Touching a charged object is only dangerous if you become a current path--if it uses you to get somewhere. Even if the earth had a net charge, you aren't providing it anywhere to go, so you will not be shocked. It's somewhat like a bird on a power line.
The following is multiple choice question (with options) to answer.
A good conductor of electricity would be | [
"tree",
"coke bottle",
"your finger",
"coke can"
] | D | An electrical conductor is a vehicle for the flow of electricity |
OpenBookQA | OpenBookQA-1891 | home-experiment, oxidation-state
Title: the perfect campfire As far as chemistry goes, there are laws or observations that can be useful to determine the perfect shape and disposition of the wood in a campfire ?
For example what chemistry says about the 2 most popular "shapes"
teepee
log cabin
or even other variations such as the swedish stove ( 1 log with the top splitted in multiple segments )
The properties that I'm looking for:
- easy to start
- long lasting
The properties that I would like to have but I can discard:
- significant heat generation From many years as a trained firefighter, I can tell you that there is certainly science involved. There are a number of very heavy calculations for calculating things like solid combustible burn time and heat release rates for combustible materials, which might possibly be useful to predict the perfect shape, fuel size and arrangement for a campfire, but are probably well beyond the scope of producing the perfect sausage sizzle. However, a number of key factors that influence fire behaviour, and which must be considered in building the best campfire include:
The following is multiple choice question (with options) to answer.
The process of building a log cabin for a dream getaway deep in the mountains near an idyllic stream requires | [
"processed cheese",
"metal panels",
"drywall",
"wood beams"
] | D | if something is a raw material in a process then that something is required for that process |
OpenBookQA | OpenBookQA-1892 | mechanical-engineering, materials, manufacturing-engineering, cooling
Title: Building a cooling system for a kneading machine? I wanted to modify my kneading machine. In fact it can work for at maximum 5 minutes, and then I have to let it cool for 20 minutes (it is a very cheap model), and it is a problem for me.
So I was thinking of adding a sort of cooling system, for instance a fan (like that used in motherboards).
I was thinking of removing the red "hat" of the machine and replacing it with a bigger hat, so that there will be space for the cooling system.
But I have the following questons:
1) Do you agree with me with the position of "cooling ports" from with the air will enter and exit (IN, OUT)?
2) How can I realize the bigger hat? Which material?
3) How can I connect the bigger hat to the machine?
4) I was thinking of doing this modification because it is a cheap model and because I think that the only problem of using it for more than 5 minutes is the excessive heat. So if we solve it with a proper cooling system, I can use it for instance for 20 minutes. Do you agree with me about this last statement?
No problems about the electrical supply of the fan because I will build an external supply circuit for it. The motors used in inexpensive, occasional-use appliances often do not have cooling fans in them because they are not designed for continuous operation. This means that cutting holes in the top case of your mixer might not help get the heat out of the motor windings- unless you added a fan for this purpose. That would be a time-intensive proposition, requiring several hours. You then have to ask yourself the question of what is an hour of your time worth?
In general, if your appliance hits its thermal cutout after 5 minutes of operation, it is the wrong tool for the purpose and should be replaced by one of higher capacity.
An alternative solution is to buy a second mixer of the same type, and let the one cool down while using the other.
The following is multiple choice question (with options) to answer.
A person wants to fix up a fan so that it can run electrically, and finds that in order to do so they require | [
"music",
"paper",
"distractions",
"copper"
] | D | wiring requires an electrical conductor |
OpenBookQA | OpenBookQA-1893 | entomology
Title: What is the name of this tiny creature? It looks like a tiny piece of moving cotton? By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name? From your image, it looks like it might be a woolly aphid. I just did a bit of cursory research, and it looks like they're often described as floating pieces of fluff, that seem to wander instead of directly heading somewhere. The fluff on their back is actually wax produced as a defense mechanism from predators and the like. I hope this is what you were looking for!
The following is multiple choice question (with options) to answer.
A thing that disperses will | [
"gather things",
"build things",
"relocate things",
"destroy things"
] | C | a disperser disperses |
OpenBookQA | OpenBookQA-1894 | homework-and-exercises, classical-mechanics, energy, momentum
Title: Impulse and car make (homework question) In my physics course it says that the more sturdy the car is the more momentum change (impulse) it will experience during a collision.
The following image is a snippet of the paragraph in my course that talks about this.
These different types of collisions can have a serious effect on people in cars. Usually, a car collision is inelastic or completely inelastic, if the vehicles stay together. Older cars were made to be very sturdy, with solid metal frames. This caused collisions to occur over shorter periods of time, and the cars to bounce back. These two factors increased the net force experienced by passengers because the change in momentum was larger and it happened over a shorter period of time.
Modern cars have "crumple zones" in the front and rear. These serve to lengthen the time of impact for the collision, as well as to absorb as much energy as possible, which decreases the chance that the cars will bounce off each other and increase the impulse. Both these factors decrease the net force on passengers, helping to reduce the number of injuries and deaths.
Why is this the case? Impulse should not change with the material the car is made from but only with the amount of seconds it is contact with the other car and the force (action-reaction) between the two cars. Impulse is simply the change in an object's momentum. When two cars collide and bounce off one another (an elastic collision), the impulse is greater than when two cars collide and stop (an inelastic collision). When the cars bounce off one another, they require enough impulse to stop the car, and then even more impulse to make them bounce back the way they came. The crumple zone reduces the total impulse by preventing the cars from bouncing back, as well as increasing the time and thereby decreasing the force required to achieve that momentum change. The crumple zone reduces the force felt by passengers both by reducing the total momentum change, and lengthening the time over which that change occurs.
The following is multiple choice question (with options) to answer.
A car rounds a corner and the driver taps the breaks. The breaks being tapped causes | [
"the car to slip",
"the car to float",
"the car to die",
"the car to speed up"
] | A | braking can cause skidding |
OpenBookQA | OpenBookQA-1895 | human-biology, reproduction, human-genetics
Title: Very frequent multiple births in humans 18th century Feodor Vassilyev is said to have had children by two wives, each of whom only ever had twins, triplets or quadruplets. His first wife has 16 sets of twins, 7 of triplets and 4 of quads; his second had 6 sets of twins and 2 of triplets. Is there any known plausible biological explanation for this, or do we have to dismiss it as a fabrication?
I could understand a woman's body being unusually susceptible to multiple births. I can't find information on whether these women tended to have monozygotic or polyzygotic offspring, but neither option seems unviable to me. However, since it's unlikely two of Feodor's sexual partners would share such a trait, one would think to attribute it to him. Presumably there would have to be a mechanism by which paternal DNA can trigger embryo fissions, in which case I imagine the offspring would be polyzygotic. Risk factors for dizygotic twinning are related to multiple follicular development, and include maternal family history, ethnicity, geography, maternal parity, maternal age, and, of course, use of assisted reproductive technology. There may be a genetic component to monozygotic twinning as well, but that rate is fairly consistent across populations. Other risk factors, such as diet and supplementation, have been proposed, but the data are less robust. There are some interesting studies demonstrating geographic clusters of twinning, but these tend to be demographic clusters that are associated with other risk factors.
Though a higher risk of twinning can be transmitted from a father to his daughters, the father's family history of twinning is not a significant risk factor (for his own children to be twins). To clarify -- if a man has a family history of multiple births, his children are no more likely to be twins than the general population, but his daughers are more likely to give birth to twins. This study is one example of the studies that have shown a significant independent association between maternal family history and twinning, with no significant independent association with paternal family history.
The following is multiple choice question (with options) to answer.
A person decides to reproduce with another person, so beforehand they | [
"find some friends",
"consider genetic implications",
"consider eating dinner",
"make a dollar"
] | B | reproduction is when an organism passes genetic information from itself to its offspring |
OpenBookQA | OpenBookQA-1896 | genetics, botany, reproduction, dendrology
So why I don't get the apple-tree of the scion kind if I plant the seeds from an apple which has grown on such a tree? I would expect that the genes in the apple seeds must be the same. However if I plant the seeds, I have to graft the new seedling again. The reason most apples are produced from grafted trees is that apples don't breed true.
In a large number of crops, you have "lines" of crops. Basically, if you breed two plants of the same cultivar together, their offspring are similar enough to both parents that it performs like the parents. The reason for this is that these crop lines have been interbreed with each other for long enough that the population is self consistent, and the important alleles are present in frequencies that mean all progeny are likely to inherit them.
However, the types of apples which are sold commercially are not from these sorts of cultivar lines. Instead, they've been obtained from "sports". That is, the chance production of either a particular hybrid gene set, or sometimes from random mutations that happened on an adult tree of another apple variety. For example, the Granny Smith occurred from a chance seedling which was discovered by Maria Ann Smith.
These apples don't necessarily have "consistent" alleles. For example, it may be heterozygous for certain genes. If you have Aa alleles at one gene, if you self-pollinate the plant, you're going to get a mix of AA, Aa and aa genes in the offspring, the last of these isn't going to be the same phenotype as the parent. Now recognize that this is happening at multiple genes across the entire genome, so there are many chances to get non-parent-like allele combinations. Add to this the issue of co-dominance, where the heterozygote has a different phenotype than either homozygote (that is, BB isn't like Bb), and the chances that an offspring has a gene with a non-parent like allele combination is pretty high.
There's a further complication that some apple varieties like Honeycrisp are self-sterile. Even if Honeycrisp could theoretically breed true, there's no way for it to fertilize itself, meaning that all fertilization events are hybridizations.
The following is multiple choice question (with options) to answer.
If a tree has large seeds, then so did | [
"the trees it came from",
"Johnny Appleseed in a pouch",
"the birds in the trees",
"the surrounding leaves and bushes"
] | A | the type of seed of a plant is an inherited characteristic |
OpenBookQA | OpenBookQA-1897 | everyday-life
Due to friction effects though, option c is still best. Pedaling hard will quickly deplete energy reserves while pedaling at a slow but steady rate will allow you to cycle for much longer. From a physics point of view, we cannot help you spend less energy, it will inevitable take about the same amount of energy regardless of your method (some +/- due to friction, etc). But by keeping your power usage low, you can go much farther before needing a rest. It is much the same as with running and walking. Simplistic physics says both use the same amount of energy, but you won't get as far by running due to the massive power requirements.
The following is multiple choice question (with options) to answer.
As an individual is forced to pedal harder on a bicycle their pulse rate | [
"stays the same",
"decreases",
"stops",
"increases"
] | D | as energy required for an activity increases , pulse will increase |
OpenBookQA | OpenBookQA-1898 | infection, amphibians
Title: What is this toad suffering from? Myiasis or chytridiomycosis? I found this toad on Aug. 29th at this location: position on osm
I think it is a bufo bufo, approx. 10 cm long. The nostrils seemed to be completely filled with a grey matter and from the activity of the floor of the mouth it apparently tried to breathe againgst this obstruction. It probably had enough oxygen via its skin though.
I tried to remove the obstruction using a blade of grass but this seemed to produce some pain as the toad closed its eyes on contact, so I stopped. The skin looked fairly normal and the toad was able to walk away after a while.
I can think of two causes for this condition.
Batrachochytrium dendrobatidis infestation
Lucilia bufonivora larvae
I could not see properly, if there were any larvae or unhatched eggs inside the nostrils, but as the rest of the skin seemed unharmed I assume the latter.
Is my assumption valid or is there even a third possibility? It is a female Bufo Bufo and you are right, there are toad fly (Lucilia bufonivora) larvae/eggs inside her nostrills. These flies lay their eggs inside toads' nostrills (specifically on Bufo Bufos) and the larvae start eating them. Sadly this disease ends up by the death of toad. They slowly eat nostrills, then mouth, eyes, and all the head.
Here's a photo of a male bufo bufo, without a head. Someone found it walking around at this situation. https://i.stack.imgur.com/I6twl.jpg
The following is multiple choice question (with options) to answer.
What does a frog eat? | [
"plantlife",
"bug microphones",
"mayflies",
"minerals"
] | C | a frog eats insects |
OpenBookQA | OpenBookQA-1899 | I was reading First Course on Probability by Sheldon Ross and I came across a problem which went like this:
"A customer visiting the suit department of a certain store will purchase a suit with probability $.22$, a shirt with probability $.30$, and a tie with probability $.28$. The customer will purchase both a suit and a shirt with probability $.11$, both a suit and a tie with probability $.14$, and both a shirt and a tie with probability $.10$. A customer will purchase all $3$ items with probability $.06$. What is the probability that a customer purchases (a) none of these items? (b) exactly $1$ of these items?"
Problem a) is easy to solve, what confuses me is part b). Ross solves it in the following way:
The probability that two or more items are purchased is $P(AB ∪ AC ∪ BC) = .11 + .14 + .10 − .06 − .06 − .06 + .06 = .23$ Hence, the probability that exactly $1$ item is purchased is $.51 − .23 = .28.$
Intuitively, I understand why he subtracts the probability of buying two or more things from the probability of buying anything at all. What I do not understand is the rigor behind it. Why am I justified in subtracting one probability from the other?
What I tried to do in order to justify this was saying $P( \mathrm {buying \ 2 \ or \ more \ things)} + P(\mathrm {buying \ 1 \ thing}) + P(\mathrm {buying \ nothing})=1$ since a customer must buy a shirt, or a tie, or a suit, or nothing, therefore the three terms above must add up to the probability of the sample space which equals one.
The following is multiple choice question (with options) to answer.
A person is going to go to the beach and plans on getting some items for swimming, so they buy | [
"wetsuit",
"canes",
"bricks",
"hats"
] | A | swimming is when humans can move in water |
OpenBookQA | OpenBookQA-1900 | meteorology, climate-change, gas, pollution
If you are interested in Greenhouse Gases (e.g. methane, carbon dioxide, CFCs, nitrous oxide), the EPA has a separate site for those emissions since they are not part of the same regulatory framework http://www.epa.gov/climatechange/ghgemissions/ . Greenhouse gases typically do not cause adverse health effects for plants or animals on land. However, they have long-term radiative effects (e.g. the greenhouse effect) because they stay in the atmosphere for many years and trap infrared light. These long-term radiative effects are what can change climate and consequently land cover. Furthermore, most of the excess carbon is absorbed by the ocean, which creates carbonic acid. Increased acidity of the ocean causes severe problems for marine ecosystems.
The EPA states that in 2012 the CO2 equivalent GHG emissions for the USA by sector was:
The following is multiple choice question (with options) to answer.
something that can negatively impact an organisms health is | [
"graduation",
"a placebo",
"chickenpox",
"chemistry"
] | C | illness has a negative impact on an organism 's health |
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