source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-601 | If the maximum number of fish caught is $$m$$, then the total number of fish caught is no more than $$m+(m-1)+...+(m-6)$$. So there is one fisherman that caught at least 18 fish. Repeat this process for the second and third highest number of fish caught and you should be good.
I should add that this is a common proof technique in combinatorics and graph theory. To show that something with a certain property exists, choose the "extremal" such something, and prove that property holds for the extremal object. For instance, to show in a graph where each vertex has degree at least $$d$$ there is a path of length at least $$d$$, and one proof starts by simply showing a maximal path has length at least $$d$$.
• If the most fish caught is $18$ that gives a tight result - there is a little work to check what happens if the largest number of fish caught is greater than $18$ Sep 30 '18 at 15:12
• @MarkBennet right, my thought was to iterate, i.e. After you choose the max $m$, replace $100$ with $100-m$ and $7$ fishers with $6$, this gives a bound on the second highest, etc. Thanks for pointing this out Sep 30 '18 at 15:15
• Not a problem - it actually gets a bit easier. This works and was my first way of doing it. Sep 30 '18 at 15:26
• Thank you for your solution. I accept Mark's solution because it is more accessible for kinds about 14 years.
– Aqua
Sep 30 '18 at 15:45
• @greedoid no prob! I would accept marks as well :) Sep 30 '18 at 15:45
I think I have a solution. First note that if $$r_4 \geq 15$$ then we have:
$$r_5 \geq 16$$
$$r_6 \geq 17$$
$$r_8 \geq 18$$
so $$r_5 + r_6 + r_7 \geq 16 + 17 +18 = 51$$ which is impossible.
Therefore $$r_4 < 15$$
The following is multiple choice question (with options) to answer.
Fish are quickly caught in water because of the webbed feet possessed by a | [
"cheetah",
"penguin",
"hippopotamus",
"snake"
] | B | webbed feet are used for moving faster through water by aquatic animals |
OpenBookQA | OpenBookQA-602 | python, python-3.x, programming-challenge
On the first day of Christmas, my true love gave to me: a Partridge in a Pear Tree.
On the second day of Christmas, my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
On the third day of Christmas, my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the fourth day of Christmas, my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the fifth day of Christmas, my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the sixth day of Christmas, my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the seventh day of Christmas, my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the eighth day of Christmas, my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the ninth day of Christmas, my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
On the tenth day of Christmas, my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
The following is multiple choice question (with options) to answer.
It was hot during Christmas in | [
"new york",
"ayers rock",
"seattle",
"denver"
] | B | December is during the summer in the southern hemisphere |
OpenBookQA | OpenBookQA-603 | thermodynamics, energy, temperature, work, volume
In particular, since a phase change happens we have a huge absorption of heat energy that doesn't result in a temperature increase because that energy instead is used for the phase transition (typically called latent heat).
Also, as the solution shows, we have to take into account the work energy that is spent for this phase change to be able to happen. Meaning, for the gas to form it must expand and "push away" the surrounding air. It must do work on the surroundings. Some energy is thus spent on doing that, and this energy delivered to the surroundings and thus removed from the internal energy.
All in all, these two energy contributions (one positive, one negative) play a role in the final internal energy that is stored in the substance. And none of them change the amount of thermal energy so we see no temperature change.
* With this I am referring to the thermal energy change within the substance that absorbs the energy. If you instead use the formula to calculate the thermal energy change within another substance which is supplying the energy, then you have calculated the amount of heat energy that is transferred from the supplier to the absorber - but we can't know from that whether the absorber converts this absorbed into an equivalent thermal energy change or to other types of non-thermal energies.
The following is multiple choice question (with options) to answer.
A phase change happens | [
"when onions are chopped",
"when food is digested by the stomach",
"when water is added to a glass",
"when flowers bloom in full"
] | B | a phase change is when matter changes from one state into another state |
OpenBookQA | OpenBookQA-604 | species-identification, ornithology
Title: Help me find out what this bird is (description, no picture) A while ago I read about this bird(s) whose species status was not confirmed. This was because they had a very large distribution and birds in adjacent population could breed with each other but birds at each end of the distribution (western Europe and South Asia I think) couldn't. I am pretty sure that they were some kind of gull and from Europe to Asia their wings got lighter, from black to grey. I think I might have read about them in a Richard Dawkins book.
Does anyone know the species I'm talking about? You're describing a Ring Species: "a connected series of neighbouring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population".
The classic ring species is the Herring Gull complex, and that's probably what you read about:
The classical example of the ring species model was originally based upon the herring gull complex (Mayr 1942). This group comprises more than 20 taxa of large gulls (Haffer 1982) which together occupy a circumpolar breeding range in the northern hemisphere. ... Mayr envisioned all taxa of the circumpolar chain to be connected by gene flow, while herring and lesser black-backed gulls in Europe, the hypothetical endpoints of the ring, have reached full reproductive isolation and now coexist as distinct species.
--The Herring Gull Complex (Larus argentatus - fuscus - cachinnans) as a Model Group for Recent Holarctic Vertebrate Radiations
However, recent genetic work shows that the situation is even more complicated than this, and it's questionable whether they really are "ring species":
Contrary to the ring-species model, we find no genetic evidence for a closure of the circumpolar ring through colonization of Europe by North American herring gulls. However, closure of the ring in the opposite direction may be imminent, with lesser black-backed gulls about to colonize North America.
--The herring gull complex is not a ring species.
The following is multiple choice question (with options) to answer.
Jim found birds living among | [
"gravel",
"space",
"cactus",
"ocean floor"
] | C | some birds live in forests |
OpenBookQA | OpenBookQA-605 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
There are creatures which, depending on species, have varying numbers of body parts. Arachnids have a certain number, while humans have a different number, and these numerous parts can be attributed to | [
"survival",
"environmental growth",
"inherited characteristics",
"developmental abilities"
] | C | the number of body parts of an organism is an inherited characteristic |
OpenBookQA | OpenBookQA-606 | thermodynamics, physical-chemistry
So the question is :
Does the chemical reaction $\rm (2KOH + CaCO_3 → Ca(OH)_2 + K_2CO_3)$ occur spontaneously? Yes or no? Why? In modern chemical theory the term 'spontaneous reaction' doesn't make much sense and isn't often used anymore.
Instead the chemical reaction (e.g.)
$$\text{A}+\text{B} \rightleftharpoons\text{C}+\text{D}\tag{1}$$
is considered an equilibrium reaction, so that:
$$K_E=\frac{\alpha_C \alpha_D}{\alpha_A \alpha_B}\tag{2}$$
where $K_E$ is the equilibrium constant of $(1)$ and the $\alpha$ are so-called chemical activities (in simple, very dilute cases these equate to the more traditional concentrations).
If $K\gg 1$ the equilibrium is 'right-leaning', if $K\ll 1$ it is called 'left-leaning'.
It is possible that in your reaction the equilibrium is sufficiently right-leaning for some $\text{Ca(OH)}_2$ and $\text{K}_2\text{CO}_{3}$ to form in your conditions. But you need to be very certain of your experimental/analytical conditions.
Yes or no? Why?
So, as so often it's not really a 'yes or no' question.
The following is multiple choice question (with options) to answer.
if a chemical reaction occurs, it might have been triggered by which of these? | [
"a person yelling at it",
"a person walking by it",
"a person looking at it intently",
"a person cranking up the room heater"
] | D | adding heat to an object sometimes causes chemical reactions |
OpenBookQA | OpenBookQA-607 | 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.
as the year progress from June to November the hours of light per day | [
"increases by a few hours",
"decreases by a few hours",
"decreases by 10 minutes",
"increases by 10 minutes"
] | B | when the seasons change from the summer to the fall , the amount of daylight will decrease |
OpenBookQA | OpenBookQA-608 | entomology
Title: The death of Earthworm In rainy season when children sprinkle salt on earthworm ,it dies.But salt is not dangerous.We use it daily.Then why earthworm dies? It's because on the earth worm skin's special mucous. Acording to this article: Why do earthworms die when salt is sprinkled on them? the mucous makes moist to the worm's skin, which is vital for their survival. Moreover, the worms don't have a respiratory organs, like lungs, gills, etc. This means that Carbon Dioxide and other characterized as "dump" gases can not be exchanged with the Oxygen. But worms breath through their skin, with the help of these special mucous that are developed on its skin. If their skin dries out the result will be death, because the gas exchange will not last without the mucous help. Similarly, the circulatory system won't function, because its main role is to trade gasses with the cells via red blood cells.
What about salinity?
Salinity is a very important factor for the earthworms health, because high salinity destroy their valunable and sensitive skin and kills the mucous that in fact help the worm to "breathe". Low salt concentrations are very beneficial for the worm, because not only their mortarity level is increaced, there are size changes to the worm's body (noticeable bigger size).
Here are and some photos of a worm that its enviroment has low salinity and high salinity:
High salinity:
Low-to-medium salinity
Source: Why do earthworms die when salt is sprinkled on them?.
The following is multiple choice question (with options) to answer.
Annelids do what to soil? | [
"loosen it",
"tighten it",
"condense it",
"clump it"
] | A | tunnels in soil loosen that soil |
OpenBookQA | OpenBookQA-609 | materials, structural-analysis, applied-mechanics, solid-mechanics, elastic-modulus
Figure 2: A Plot of Potential Energy versus Internuclear Distance for the Interaction between Two Gaseous Hydrogen Atoms. (source: libretexts
The atoms want to settle at the lowest energy point. If you compress/pull them apart then you quickly get a response back, which is the force. The more you pull/push, the higher up you go to the potential well and the higher the force.
Additionally, if you remove the external stimulus (the force you are applying), all that potential energy quickly returns the material to the "resting state".
(That doesn't explain plastic deformation, but its beyond the scope of this question).
Where does the extra energy go
Only a small part of your energy you are expending when you are pushing on the wall is stored as elastic energy.
The rest of the energy that is being burned away, is converted to heat from you body which is trying to maintain the force.
I guess an example that can help you understand that, is if you try to hold a bottle of water on the palm of your hand. You can try it in two ways
like the following image (arm extended)
Figure 3: bottle in hand not supported (source: saltysoulsexperience.com
everything is the same apart from the fact that you can support the back of your hand on a table.
You will be able to sustain position 2. a LOT longer, and the only reason is that the muscles will not need to contract as much in the second case.
excellent resource
An excellent book about this is Prof. Gordon's "The New Science of Strong Materials: Or Why You Don't Fall through the Floor", although it has only a handful of equations if you are interested, and its almost bed time reading (or sometimes a bit more than that).
The following is multiple choice question (with options) to answer.
What shows that crumpling is to change something from being smooth into a compacted shape by physical force? | [
"folding a piece of paper into a shape",
"crushing a can in your hand",
"squishing a smooth bug",
"ripping up a piece of paper"
] | B | crumple means change shape from smooth into compacted by physical force |
OpenBookQA | OpenBookQA-610 | climate-change, climate
In this case, as it is an area that it is almost constantly cloudy with high humidity, temperature is varying just a little bit, and except the first day of the period, it seems that there is no relationship. In fact, on the second day there was a storm (I am living now at Singapore) and it is reflected in a quick change in temperature (both) and solar radiation.
Conclusion: It is not as simple as it seems.
Hope it helps!
The following is multiple choice question (with options) to answer.
The past week has been warm, humid and foggy. As the weather is supposed to cool a little bit tomorrow, a reasonable person could assume that tomorrow will be | [
"rainy",
"clear",
"hot",
"steamy"
] | A | water vapor condensing in clouds causes rain |
OpenBookQA | OpenBookQA-611 | natural-satellites, crater, hyperion
Title: What caused these strange craters on Hyperion? I was looking at pictures of the moons of Saturn and noticed that the craters on Hyperion have a strange shape, somewhat resembling sinkholes. They look a lot deeper than the impact craters on other moons (including ours). Is it an optical illusion (perhaps caused by the presence of dark material at the bottom of the craters?) that somehow makes them look deeper? If not, what process caused these holes to appear? According to Thomas et al. (2007), these craters are not unusually deep:
It is unlikely that unusual crater depths significantly enhance the sponge-like appearance. Crater depth-to-diameter ratios for the 13 examples that can be measured reliably using shadow lengths average 0.21 ± 0.05 (s.d.). These ratios are similar to values for fresh lunar craters, and are slightly greater than for some small rocky objects. They are slightly larger than that for craters on large icy satellites, 0.14.
What is unusual and gives a "sponge-like" appearance to Hyperion is the high density of craters and lack of intercrater plains:
For craters with diameters between 2 km and 11 km, Hyperion has a cumulative number of craters per unit area twice that on Phoebe; at similar resolution these objects are strikingly different.
To explain this, they proposed that ballistic ejecta from impact events, which usually cover older craters, are lost to space instead.
A more recent study (Howard et al., 2012) suggested that mass wasting processes (landslides) and CO$_2$ sublimation also account for this special morphology, especially for the dark-floored craters. This has been confirmed by Dalton et al. (2012), who called these craters "suncups":
The irregular shapes of the sublimation pits (suncups) support the
hypothesis of extensive mass wasting and sublimation degradation
(Moore et al., 1996, Howard et al., 2011, Howard et al., 2012) largely
associated with the loss of volatiles (including water ice). When the
ices evaporate, entrained low-albedo grains accumulate in lag
deposits, which are subject to solar heating. Warm grains accelerate
both the local evaporation of ices and their own spatial
concentration.
The following is multiple choice question (with options) to answer.
What forms craters on planets? | [
"sunlight",
"thunder",
"space stones",
"digging"
] | C | usually craters on planets are formed by asteroids impacting that planet or moon 's surface |
OpenBookQA | OpenBookQA-612 | dna, mammals, eggs
Title: In what circumstances does a mammalian egg copy its DNA? In the 2nd episode of the new Cosmos series, the host Neil deGrasse Tyson shows how the white-furred bear could have evolved (reasonable scientific speculation, of course).
If you haven't seen that episode, here's the link. Great show, by the way.
So, it shows the bears eggs, and then goes on to show how there can happen an error in the DNA copying, that leads to the brown pigment production malfunction. Here's an excerpt from the subtitles text:
- great bears roamed the frozen wastes of Ireland.
- This might look like an ordinary bear,
- but something extraordinary is happening inside her.
- Something that will give rise to a new species.
- In order to see it, we'll need to descend down to a much smaller scale, to the cellular level, so that we can explore the bear's reproductive system.
..
- Those are some of her eggs.
- To see what's going on in one of them,
- we'll have to get even smaller.
- We'll have to shrink down to the molecular level.
..
- When a living cell divides in two,
- each one takes away with it a complete copy of the DNA.
- A specialized protein proofreads to make sure
- that only the right letters are accepted
- so that the DNA is accurately copied.
- But nobody's perfect.
- Occasionally, a proofreading error slips through,
- making a small, random change in the genetic instructions.
- A mutation has occurred in the bear's egg cell.
- A random event as tiny as this one can have consequences on a far grander scale.
- That mutation altered the gene that controls fur color.
- It will affect the production of dark pigment in the fur
- of the bear's offspring.
The following is multiple choice question (with options) to answer.
When a bear eats berries he will be contributing to what process? | [
"food for young",
"hunters",
"seed propagation",
"hunger"
] | C | An example of seed dispersal is animals eating seeds |
OpenBookQA | OpenBookQA-613 | 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.
Bats hunt through echolocation because | [
"bats can only hear echoes",
"echoes are a form of sound",
"their chirps are sent back after bouncing",
"they enjoy listening to echoes"
] | C | echo is when sound reflects off of a surface |
OpenBookQA | OpenBookQA-614 | Thanks again!
Josh
1. Hi Josh,
My friend and I used a large piece of plywood for the base, and basically three more pieces of wood stuck together in a U-shape for the rest of the frame. However, I think even a design as simple as the one here would work well if you have little woodworking experience.
As for your other questions: I am an undergraduate, and I do plan on going to graduate school.
Feel free to ask more questions if you've got any!
Cheers,
Paul
55. may i ask one question. when making a pendulum wave, what do you use for the balls??
1. Hi there,
Sorry for the late response!
I simply used a pack of bouncy balls I got from the dollar store. The material of the ball doesn't really matter as long as its reasonably solid (so air drag is not a concern).
Cheers,
Paul
56. This is great! I just have a few questions, would I get the same effect if I only used 12 pendulums? Secondly, how come the difference between the lengths are non linear? And lastly is the lengths given from the top to the centre of the ball or for each string? Thanks for your time!
1. Hi there,
Thanks for the comment! As for your questions:
1. The same effect would be present with only 12 pendulums (though it would be slightly reduced).
2. The lengths are expected to be non-linear due to the fact that the period of a pendulum depends on the square root of the length, and not any other power.
3. The lengths are given from the top to the centre of the ball. They are only a rough approximation of the lengths needed. Make sure you leave a couple extra centimetres for manually calibrating the machine.
Cheers,
Paul
57. Hi Paul,
Love your site! Hopefully I'm sending more than a few visitors your way :)
I thought it was pretty cool to see from the comments that someone did this at The Burning Man. I bet that was quite a sight!
We need more science blogs out there like yours. I just want to thank you for sharing your interests with the world.
1. Thanks Chris,
I appreciate it!
58. Sorry Paul but can you tell me the distance between each ball???
1. The distance between each ball does not matter. Just make them spaced out enough so that the balls do not collide with each other.
The following is multiple choice question (with options) to answer.
What could be used to fill a beach ball? | [
"Aluminium",
"Iron",
"Oxygen",
"Water"
] | C | a beach ball contains gas |
OpenBookQA | OpenBookQA-615 | redox, combustion, carbohydrates
Title: Why do gummy bears explode when added to hot potassium chlorate? This link shows that a gummy bear explodes when in contact with heated potassium chlorate, $\ce{KClO3}$. But what in a gummy bear creates this reaction?
Also, do other foods (fruit, icing sugar...) react as violently with potassium chlorate? Potassium chlorate is a source of oxygen. After heating, it decomposes to $\ce{O2}$ and $\ce{KCl}$:
$$\ce{4 KClO3 → KCl + 3 KClO4}$$
$$\ce{KClO4 → KCl + 2O2}$$
The gummy bear is mainly composed of sugar and other carbohydrates. Those carbohydrates will react with oxygen, combustion occurs. For example, glucose will react in this manner:
$$\ce{6O2 + C6H12O6 -> 6CO2 + 6H2O}$$
If there is any material present which does not burn, such as $\ce{H2O}$, the temperature will not rise as high. For gummy bears the reaction works spectacularly because they are mainly carbohydrates (>70%).
An apple, for example, has only ~13% carbohydrates – unless you dry it, of course. On the other hand, this video on YouTube is an example of how sugar itself reacts violently with potassium chlorate.
The following is multiple choice question (with options) to answer.
an animal needs to burn complex carbohydrates to | [
"stay up",
"move",
"sit",
"sleep"
] | B | an animal requires energy to move |
OpenBookQA | OpenBookQA-616 | zoology, ecology, population-biology, ecosystem, predation
Title: Predator prey interaction I went through a line in my textbook which read:
"But for predators, prey species could achieve very high population densities and cause ecosystem instability."
I was not able to understand the meaning 'but for predators'. Can anyone please help me to interpret it's meaning?link to page where this line is mentioned
Edit: In terms of biology, I was unable to understand the meaning of the sentence, and I wanted to make sure that I don't misunderstand things... And this is why I posted the question.. I feel that the answer given is correct and in case, you find better explanation, please do post. I disagree with GForce's explanation; the meaning is not that growth of prey populations causes instability in predator species.
The sentence is merely saying that without predation, prey population growth is more likely to be at a level which leads to ecosystem instability. The term "but for predation" means "if it wasn't for the effects of predation". In other words:
"Ecosystem instability can occur when population growth of some species goes unchecked by predation."
See here for more explanation, where this example comes from in which it says that running a red light caused a crash:
"but for running the red light, the collision would not have occurred"
Biologically this makes sense in the sentence you show; without predators a species is limited by its supply of resources, and it can use these resources at an unsustainable level, whereas if you add predators to the mix there is additional extrinsic effects on population size, not determined by ecosystem properties such as space or nutrients.
The following is multiple choice question (with options) to answer.
What do predators live near in the same environment? | [
"Their future Prey",
"Their water source",
"Their offspring",
"Their dens"
] | A | most predators live near the same environment as their prey |
OpenBookQA | OpenBookQA-617 | planet, orbit
Title: Do the orbits of planets change sometimes? Do planets sometimes wobble and get off their paths? What if an asteroid were to hit it? Yes, the orbits change massively over time. For example, Earth's eccentricity (how close to a circle the orbit is), its axial tilt (what causes seasons), and precession (which direction the Earth's spin axis points) change on these huge cycles, tens of thousands to hundreds of thousands of years long. They are caused by the pull of the other planets, mainly Jupiter and Saturn (since they are so huge), as well as the physics of inertial reference frames. These are known as the Milankovitch cycles. Here is a neat video explaining what each of the cycles are in detail. That video is about Earth, but the same concepts apply to all the other planets too, just on different amounts and timescales.
An asteroid hitting a planet would technically change its orbit, however how much is questionable. An asteroid a couple km across would barely nudge the Earth since the Earth is bigger by many orders of magnitude. It would also destroy everything on the planet, but thats another story. Way back in the solar system's formation, when Thea hit Earth (theoretically) it was much closer in size than the Earth, so no doubt that it caused a much more significant shift in orbit.
The following is multiple choice question (with options) to answer.
What causes orbits? | [
"pulling down",
"sunlight",
"planetary pull",
"solar flares"
] | C | gravity causes orbits |
OpenBookQA | OpenBookQA-618 | visible-light, electromagnetic-radiation, frequency, sun
(Note, there are other possible emission spectra, but those are associated with different materials doing the emissions and, for the purposes of this discussion, they aren't too important. We can just claim the emissions are all blackbody)
If you notice, as you get hotter, a larger portion of the energy is emitted in the blue, violet, and ultraviolet. That's how you get a sunburn from the sun. It's harder to get a sunburn from an artificial light, not because it's artificial, but because those lights are almost always cooler than the sun. They don't have as much UV content. Instead, they have more red and yellow, which incidentally is why pictures taken indoors look very yellow. If you use a strobe, however, all those yellow hues go away because a strobe light is very warm, with lots of blues.
You can get a sunburn from artificial light, of course. Tanning beds are the obvious example, but there are other interesting ones. When you're a jeweler working in platinum, for instance, you need to wear UV protective gear (like glasses or even sunscreen). Platinum's melting point is so hot that it actually emits quite a lot of UV light and can give you a sunburn!
Other than these spectra, there is nothing different between light from an artificial source and light from the sun. Photons are photons.
The following is multiple choice question (with options) to answer.
sunlight is a heat source emitted from | [
"a white dwarf star",
"our only yellow star",
"a nearby quasar star",
"a red giant star"
] | B | the sun is a source of heat called sunlight |
OpenBookQA | OpenBookQA-619 | palaeontology, herpetology
Title: How big can cold-blooded animals get? It seems impossible to have reptiles the size of dinosaurs, just because they are really big! Did they have different systems of maintaining body temperature or maybe they weren't the exact type of animals that we today call reptiles? Answer is quite simple as from @Alan Boyd link. They are cold blooded and thus, can go out for hunt in cold, they need to stay put till they get some prey.
So, it mainly depend on the temperature of the outside, I found this interesting paper on relation of body sizes and latitude.
Body sizes of poikilotherm vertebrates at different latitudes
Maximum sizes of 12,503 species of poikilotherm vertebrates were
analyzed for latitudinal trends, using published data from 75 faunal
studies. A general trend appears which may be summarized by the rule
"among fish and amphibian faunas the proportion of species with large
adult size tends to increase from the equator towards the poles". The
rule holds for freshwater fish, deepsea fish, anurans, urodeles, and
marine neritic fish arranged roughly in order of decreasing clarity of
the trend). In general the rule applies not only within these groups
of families but also within single families. In reptile groups, the
rule holds weakly among snakes and not at all among lizards or
non-marine turtles. Possible explanations include an association
between small size and greater specialization in the tropics; the
possibility in poikilo-therms of heat conservation or of some other
physiological process related to surface/volume ratio; selection for
larger size in regions subject to winter food shortages; and an
association between large adult size and high reproductive potential
in cold regions. Other suggestions can be advanced, but all are
conjectural and few are subject to test. Global size - latitude trends
should be looked for in other living groups.
Cite: Lindsey, C. C., 1966: Body sizes of poikilotherm vertebrates at
different latitudes. Evolution: 456-465
Now lets compare some of the largest cold blooded Animals:
Reptiles
Amphibians
Fishes (Pisces)
The following is multiple choice question (with options) to answer.
A reptile's body temperature | [
"will sync with their climate",
"will keep stable under any circumstances",
"reacts as other warm blooded animals temperature would",
"plunges rapidly in warm climates"
] | A | as temperature in the environment increases , the body temperature of a reptile in that environment will increase |
OpenBookQA | OpenBookQA-620 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
plants gather their nutrients from the | [
"tinder",
"concrete ground",
"area under grass",
"store"
] | C | soil contains nutrients for plants |
OpenBookQA | OpenBookQA-621 | general-relativity, mass, density
Title: What happens when I increase the density of a stellar object so that its mass surpasses the Schwarzschild limit? We know that every object that has mass, also has a Schwarzschild radius $r_s$: $$r_s = \frac{2Gm}{c^2}$$
With $G$ being Newton's gravitational constant, $m$ the mass of the object and $c$ the speed of light in vacuum. When we say that the object has spherical shape, its volume $V$ is given by $$V=\frac43\pi r^3$$ This volume also equals the ratio of mass to mass density, so substituting the Schwarzschild radius for $r$ gives as a 'Schwarzschld density' $\varrho_s$: $$V=\frac43\pi r_s^3\overset{!}{=}\frac m\varrho_s\Longleftrightarrow\varrho_s = \frac{3}{4\pi}\frac{1}{m^2}\left(\frac{c^2}{2G}\right)^3 $$
Numerical evaluation of the constants gives therefore $$\varrho_s = \frac{1}{m^2}\cdot 7.29\times10^{79}\:\mathrm{\frac{kg^3}{m^3}}$$
Now let's assume in a gedankenexperiment that I built a machine capable of increasing my planet's density. I increase it to the very brink of collapse, but stop the machine so that the Schwarzschild radius is just barely smaller than the radius of my planet neutron star. Then, I call a friend of mine over for a beer and a snack.
What happens when my friend visits me with his rocket, but right before he can initiate the breaking maneuver I turn my machine back on and turn my 'home' to a black hole?
The following is multiple choice question (with options) to answer.
If the mass of an object increases, what must the volume do for the density to stay the same? | [
"increase",
"decrease",
"stay the same",
"become zero"
] | A | density is a measure of mass over volume |
OpenBookQA | OpenBookQA-622 | java, tree
path.setChild(node.right);
}
else
{
boolean direction = Math.random() >= 0.5;
path.push(direction);
while(path.grandChild(!direction) != null)
{
path.push(!direction);
}
node.key = path.child().key;
node.value = path.child().value;
path.setChild(path.grandChild(direction));
}
path.pop();
balancePath(path);
return null;
}
public V search(K key)
{
// Standard binary search.
Node search = root;
while(search != null)
{
int compare = key.compareTo(search.key);
if(compare == 0)
{
return search.value;
}
search = search.child(compare > 0);
}
return null;
}
private Path getPath(K key)
{
/* Returns a path from the root to the key specified or the
* position it would be added in if it does not exist. Includes
* the root edge.
*/
Path path = new Path(new Edge(null, false));
while(true)
{
if(path.child() == null)
{
return path;
}
int compare = key.compareTo(path.child().key);
if(compare == 0)
{
return path;
}
path.push(compare > 0);
}
}
private void rotate(Edge edge, boolean direction)
{
/* Rotates the child of the edge with its child
* in the direction specified. It is assumed both the child
* and grandchild are not null.
*/
Edge rotate = new Edge(edge.child(), direction);
edge.setChild(rotate.child());
rotate.setChild(rotate.grandChild(!direction));
edge.child().setChild(rotate.parent, !direction);
}
private int height(Node node)
{
if(node == null)
{
return -1;
}
else
{
return node.height;
}
}
private void balancePath(Path path)
{
/* Follows a path up the tree performing AVL rebalancing
* and height updates as needed.
*/
while(path.peek() != null)
{
int previous = path.child().height;
The following is multiple choice question (with options) to answer.
If a tree in your backyard rots away for is knocked over by the wind, you can just | [
"plant another",
"Draw one",
"climb one",
"do nothing"
] | A | a tree can be replaced by planting a new tree |
OpenBookQA | OpenBookQA-623 | fluid-dynamics, pressure, flow, bernoulli-equation
The constriction in this case is between the wedge of the autobailer and the water further away from the hull of the boat: when the boat passes over a given 'parcel' of water, the wedge applies a force forward and downward (perpendicular to the plane of the wedge). The fact that the water is incompressible means that to pass the wedge, the flow relative to the boat must speed up.
It doesn't matter whether it's the boat or the water that's moving; only the relative velocity between the boat and the water is important in this case.
The pressure of the static sea water at some distance from the boat can't be lower than the air pressure, but that in the thin layer which is accelerated by Bernoulli's principle can be the same as the air pressure, meaning that the suction will continue until there's no water left in the cockpit.
Let's look at the situation with the aid of a diagram:
You can see how, from the boat's point of view, the water far from the hull has a velocity $-V_\mathrm{boat}$. The dashed lines represent streamlines; lines along which a given 'parcel' of water moves. As the flow of water past the boat is constricted by the wedge, notice how these lines get 'squished' together. Water cannot be compressed (i.e. $\rho$ in the above equation cannot change), so to get the same amount of water past the wedge in the same time, the water must speed up ($V$ must increase) and hence the pressure must drop ($P$ must decrease).
The following is multiple choice question (with options) to answer.
A river can push tin cans down the path of the water because | [
"it has motion",
"it is wet",
"it is loud",
"it is strong"
] | A | flowing liquid can push objects |
OpenBookQA | OpenBookQA-624 | 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.
What kind of animal returns to the same beaches each year to give birth? | [
"saltwater crocodile",
"carnivorous bird",
"semiaquatic mammal",
"tiger shark"
] | C | seals every year return to the same beaches to give birth |
OpenBookQA | OpenBookQA-625 | java, beginner, battle-simulation
}else if (action.equals("a") && enemyChoice == 3){
checkHealth();
System.out.println("OH! "+pName+" JUST GOT SMASHED!");
playerHealth -=10;
checkHealth();
}else if (action.equals("b") && enemyChoice == 3){
checkHealth();
System.out.println("Rocky just got smashed!!!!");
enemyHealth-=10;
checkHealth();
}else if (action.equals("b") && enemyChoice == 1){
checkHealth();
System.out.println(pName+" better step up his game!");
playerHealth-=10;
checkHealth();
}else if (action.equals("c") && enemyChoice == 1){
checkHealth();
System.out.println("Rockey just got pucnhed so hard that he might not even know he exists!");
enemyHealth-=10;
checkHealth();
}else if (action.equals("c") && enemyChoice == 2){
checkHealth();
System.out.println(pName+" Just got smashed!");
playerHealth -=10;
checkHealth();
}else if(action.equals("a") && enemyChoice == 1){
System.out.println("Their fists collided! this is intense!");
}else if(action.equals("b") && enemyChoice == 2){
System.out.println("Their fists collided! this is intense!");
}else if (action.equals("c") && enemyChoice == 3){
System.out.println("Their fists collided! this is intense!");
}
}
}
The following is multiple choice question (with options) to answer.
Something can be classed as hitting if | [
"a thing is touched",
"someone becomes injured afterwards",
"a hand is raised",
"a pain is caused"
] | A | An example of hitting something is dropping an object onto that something |
OpenBookQA | OpenBookQA-626 | electromagnetic-radiation, water, ice, microwaves
Title: Could a microwave oven be tuned to defrost well? Typical microwave ovens do a lousy job of defrosting because liquid water absorbs their radiation far better than ice. So once a spot melts, it will quickly rise to cooking temperature while the rest of the food remains frozen. Would it be possible to build an oven that uses microwaves absorbed preferentially by ice instead, so it would defrost well? Such an oven would presumably be inefficient for cooking, but still valuable. It would be very difficult to do so. Microwaves heat by adding energy at resonant frequencies of the molecules. Ice and water have very different ranges:
The ease of the movement depends on the viscosity and the mobility of the electron clouds. In water, these rely on the strength and extent of the hydrogen-bonded network. In free liquid water, this movement occurs at GHz frequencies (microwaves) whereas in more restricted 'bound' water it occurs at MHz frequencies (short radiowaves) and in ice at kHz frequencies (long radiowaves).
A radio wave in the GHz region is less than 1m long, which makes it easy to work with in the spaces a microwave has to work with, and easy to generate with reasonable sized antennas. As it turns out, microwaves must operate in the 2.450 GHz band because that's the band allocated to microwaves by the FCC. That's a wavelength of roughly 12cm, so the antennas are very reasonable indeed.
Closer to 1kHz, a region known as VLF, we find wavelengths of almost 3000km. This means our antennas have to be much shorter than their associated wavelength, which makes them much less efficient. Most of the energy of such an antenna doesn't actually get emitted from the antenna. It is typically sent to ground as "waste." I'd have to consult an antenna expert to get a real answer, but 10% efficiency is not unheard of for VLF antennas.
The following is multiple choice question (with options) to answer.
Heating ice | [
"changes it's chemical make-up",
"will leave a puddle",
"requires a deep freezer",
"makes it even colder"
] | B | heat can change the state of matter |
OpenBookQA | OpenBookQA-627 | orbit
Title: Traveling constantly towards West. That is clockwise If I travel against against the Earth's rotation. Say once around the world. I will always see sunrise and never a sunset
Is that accurate? If you travel west so quickly that you go around the world in one day (24 hours) then the sun will remain almost fixed in the sky. You will see neither a sunrise nor a sunset. At a latitude of 45 degrees north, you will need to travel at 1180 km/h (faster than a commercial jet, nearly Mach 1)
If you travel less quickly, then the sun will move from East to West, but rather more slowly. You may see multiple sunrises and sunsets, depending on your speed.
If you travel faster, the sun will move from West to East in the sky. Again, you may see multiple sunrises and sunsets, but the sun would rise in the West.
The following is multiple choice question (with options) to answer.
Where is the sun at noon | [
"straight above your head",
"off 20 degrees to the southwest",
"near the western horizon",
"on the other side of the earth"
] | A | the sun is located directly overhead at noon |
OpenBookQA | OpenBookQA-628 | hygiene
What would sanitizer fail to do that detergent and warm water would do in cleaning glasses frame that isn't 'visibly soiled'?
While alcohol based sanitizers are effective at killing most pathogens, it's typically on par with a soap and water scrub. However, for the purposes of sanitation (which seems to be the only reason you'd need to clean frames that are "not visibly soiled") there are several indications for which alcohol based sanitizers are considered ineffective and inferior to soap and water. This is generally because of the specific physiology or life cycle stage of certain organisms which allow them to be resistant to the biocidal effects of alcohol. Common examples include Cryptosporidium, a water-borne protozoan parasite, norovirus, a non-enveloped intestinal virus that spreads notoriously fast in hospital environments and on cruise ships, and almost all endospore-forming bacteria, like Clostridium perfringens and Clostridioides difficile. In the lab, we actually use alcohol to isolate live bacterial spores from the vegetative components of a culture. It has also been reported that alcohol based sanitizers are more likely to cause allergic reactions (e.g. contact dermatitis) from skin exposure.
Most of these statements can be referenced in this open-access article on PubMed, with links to primary sources if you're interested in following up more.
Gold NA, Mirza TM, Avva U. Alcohol Sanitizer. 2020 Jun 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513254/#
The following is multiple choice question (with options) to answer.
Scrubbing a toilet is | [
"predestined",
"innate",
"genetic",
"learned"
] | D | doing chores is a learned characteristic |
OpenBookQA | OpenBookQA-629 | climate-change, glaciology, ice-sheets
Title: Can ice caps reform if they disappear? Excuse my ignorance. I'm under the impression that there are various types of ice at the poles, but I don't know the difference or the significance of each type, so, in terms of whatever is actually melting in these areas as a result of climate change, is it possible that it could come back if greenhouse gas emissions were eliminated or something like that? Basically, I'm assuming that the ice caps are necessary in order to maintain the habitability of the planet for humans, so is there some sort of threshold of melting that would essentially count as a point of no return or is there always the possibility of seeing the ice caps return to safe levels? Yes, polar ice can melt -- significantly, if not completely, with substantial effects on human civilization. And it can stabilize and recover, but the question is at what pace relative to human civilization.
There are generally three types of polar ice:
Ice sheets: "An ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles). The two ice sheets on Earth today cover most of Greenland and Antarctica."
Ice shelves: "Permanent floating sheets of ice that connect to a landmass."
Sea ice: "Sea ice is frozen ocean water. It forms, grows, and melts in the ocean. In contrast, icebergs, glaciers, and ice shelves float in the ocean but originate on land."
Sea ice is usually 1-2 meters thick; shelf ice is 100-200 meters thick; sheet ice is one to several kilometers thick.
The poles differ significantly. It's often pointed out that the Arctic is an ocean surrounded by land and the Antarctic is land surrounded by ocean. The North Pole is occupied by sea ice, about half of which melts every summer and reforms every winter.
At the other extreme are the ice "caps," more or less the ice sheets in Greenland and Antarctica that extrude ice in the form of glaciers and ice shelves that continuously flow into the ocean, breaking apart and melting.
To take just Greenland: Greenland has had some degree of glaciation for ~38 million years, but lost much or almost all of its ice during a warming period about 400,000 years ago, suggesting that the current ice sheet was created in that time.
The following is multiple choice question (with options) to answer.
Melting of polar icecaps will | [
"lead to more some US states gaining surface area",
"lead to more animal species roaming the Earth",
"cause the loss of animal habitats",
"cause a boom in the polar bear population"
] | C | as the level of water rises , the amount of available land will decrease |
OpenBookQA | OpenBookQA-630 | motors, rail
Title: Why would a specfication for a motor require that overtemperature protection be realized by modeling heat generation and not with an embedded sensor? I'm reading the procurement documents for the R211 railcar contract, which is for electric multiple unit subway cars designed for rapid transit applications in New York City. The railcar's propulsion is specified to use AC induction motors powered from PWM inverters with IGBTs.
The specification related to propulsion motor overcurrent is given as follows:
10.3.20.2 Over-temperature protection shall be provided as follows:
a) If the winding temperature rises 27°F above (15°C above) the operating class temperature limit, the control unit shall decrease the motor duty cycle by removing the dynamic braking and converting to frictional braking, until the temperature falls below the operating class temperature.
b) If the winding temperature rises above its design class operating temperature limit, the control unit shall remove power to the affected truck, until the temperature falls below the operating class temperature. The condition shall be reported and recorded by the MDS.
c) Motor temperature shall be calculated using a thermal model of the motor and the power that the motor is handling.
d) The measurement of winding temperatures using embedded sensors is not permitted.
Points c) and d) stand out to me as a little bit strange, since the motor is expected to be modeled with its loads, instead of directly measuring the temperature. The only reasoning I can determine for this is that it protects against the failure of the thermal sensor.
However, it's not clear to me why this failure more is harder to guard against, than (for example) the failure of current sensors needed to track the motor's power, or an obstruction of the normal cooling process by dust or debris. Is there a common technical reason why motor thermal protection is specified to use only modeled heating rather than measured heating or a combination of safeguards? Yes. Along with your reasoning of failure mode, reliability and cost, there is a disadvantage of slower response time of the sensors. The thermal model will give temperature values as fast as the speed of the digital processor you use. A Research by GE states:
An additional reason to reject such
temperature sensors as the main basis for thermal protection,
is the fact that the traditional Resistance Temperature Detector
(RTD) has a relatively slow reaction time and can’t respond
adequately to the high speed of the heating process during
motor acceleration.
The following is multiple choice question (with options) to answer.
if the temperature gauge on a dashboard goes up while vehicle is motion, what could be responsible? | [
"the snow falling outside",
"the rubbing of the mechanical parts",
"the car sales man",
"the anger of the driver"
] | B | friction causes the temperature of an object to increase |
OpenBookQA | OpenBookQA-631 | the-sun, solar-system, jupiter
Title: Is the Jupiter-Sun system considered a binary system of some type? Since Jupiter is very massive, it is the only planet (in our solar system) that has a center of mass with the Sun that lies outside the volume of the Sun. (Source)
If Jupiter was a star, they would form a « binary star ».
If the Sun was a planet, they would form a « double planet ».
Since the Sun is a star and Jupiter is a planet, does this have a particular name?
Does Jupiter have a special status or a particular effect in our solar system because of its heavy mass?
Since Jupiter-Sun's center of mass lies outside the volume of the Sun, that means that the Sun moves around that center of mass. Does this have an effect on Mercury, Venus, Earth and Mars orbits? I'm not sure I understand your question entirely, but i'll do my best to offer a decent answer. It's true that the composition of Jupiter is very similar to that of the Sun (very similar approx. $H$ and $He$ abundance and pretty similar in density). The problem is that Jupiter is not nearly massive enough to have the internal pressure and temperature to undergo nuclear fusion. Jupiter doesn't have any particular special status aside from being the King of Planets in our solar system.
As for the last part of your question, all objects orbit around a center of mass. Though because the Sun is much more massive, the center of mass lies very close to the center of the star (except in the case of Jupiter, where the CoM lies outside of the sun and is approx the length of its radius). This is why all planets in our solar system orbit around the sun. This will indeed cause a slight perturbation of orbital alignment, but I don't believe it's significant.
The following is multiple choice question (with options) to answer.
The star that Jupiter revolves around is the source of solar energy called | [
"sunlight",
"moonlight",
"ultraviolet light",
"fluorescent light"
] | A | the sun is the source of solar energy called sunlight |
OpenBookQA | OpenBookQA-632 | entomology
Title: Constantly wiggling moth pupa - will it emerge soon? Today I found a moth pupa in the soil in my garden in western Sweden. It's about 15 mm long.
I have found similar ones before, but this one is wiggling a lot more, even after I put it down and put a bit of dirt over it. It's been moving for more than an hour now, but less now than in the beginning.
I was hoping to see it emerge, but if it will take more than a day or so, I will probably put it back. So, what I'm wondering is if this wiggling is any indication of how soon it will emerge. Or if there are other ways to tell.
Update: an hour later it has stopped moving. Maybe it was just very disturbed by my presence. I'm keeping it in a jar with soil and a stick for climbing up on, and I'll decide what to do with it tomorrow.
Update: 12 hours later and it seems very still. But I'm letting the question remain since I really want to know if there are any signs to look for.
Final update: After 16 days it had turned almost black, and was still very active when handled.
And after 17 days this moth came out: I posted the same question on tumblr and got an answer:
It depends on the species. This one looks like a Noctuid. I’d give it
two weeks to a month or so. You may be able to see its wings showing
through the darkening pupal case when the time draws near! Just make
sure you give it somewhere to climb up and expand its wings when it
ecloses.
After keeping it until the moth emerged, I now know that wiggliness is not an indication of maturity, but turning dark is.
The following is multiple choice question (with options) to answer.
Certain moths are able to experience incomplete metamorphosis by | [
"skipping cocooning",
"eating more fruit",
"flying further",
"breeding quickly"
] | A | incomplete metamorphosis is when an insect reaches the adult stage without being a pupa |
OpenBookQA | OpenBookQA-633 | bacteriology, antibiotic-resistance, research-process
Title: How do scientists kill the bacteria they themselves made resistant? I was reading this article on researching bacteria resistance to silver by removing some of their genes.
Researchers then used "colony-scoring" software to measure the differences in growth and size of each plate's bacterial colony. E. coli strains with genes deleted involved in producing sensitivity, or toxicity, to silver grew larger colonies. Strains with genes deleted involved with resistance grew smaller colonies.
Once you end up with some resistant bacteria and you're done researching it, you can't just flush it down the toilet. How do you safely dispose those colony plates in a way that ensures those bacteria don't get out into the wild and reproduce? You are absolutely right, flushing down the toilet (or the sink) or simply throwing them into the normal waste doesn't work for biosafety reasons. And it is also not allowed, depending on the country you would do this in, this can lead to hefty fines.
Biologically contaminated lab waste can be inactivated (=all potential dangerous organisms are destroyed) by two ways: Either by heat or chemically. Which ways is used, depends on the kind of waste.
The most commonly used way is autoclaving, meaning treating the waste with steam at high temperatures at higher pressure. The temperature used here is usually 121°C, the exposure time depends on the volume of the waste, since the temperature needs to be reached and kept for at least 20 minutes. See the references for more details.
Liquid wastes (like culture media) can also be inactivated chemically by adding chlorine bleach to decompose the cells. Bleach can also be used to decontaminate surfaces, although here more often alcoholic solutions (70% Ethanol or Isopropanol) are used. After chemical inactivation, the remaining solutions should not be autoclaved as the emerging fumes are either unhealthy (bleach) or explosive (alcoholic solutions) and this is unnecessary, too.
Liquid wastes can also be autoclaved to inactivate them.
Autoclaving has the main advantage that it is rather simple (put the waste into the autoclave, close it and run a appropriate program), the waste can afterwards simply be discarded as normal waste, which may not be the case for chemically inactivated waste, which may need special precaution for disposal.
References:
The following is multiple choice question (with options) to answer.
Decomposers are important for | [
"construction",
"fire",
"rocks",
"dolphins"
] | D | decomposer is a kind of role in an ecosystem |
OpenBookQA | OpenBookQA-634 | electromagnetism, visible-light, acoustics
As an aside - sound can also travel "through the wall"; the pressure waves will cause slight motion of the wall which in turn causes waves on the other side (although much reduced in amplitude because of the acoustic mismatch between the air and the wall; this is where the "glass against the wall" so beloved in 50's movies can help). In principle, electromagnetic waves can also travel through walls (which is why your radio works indoors) - but again, the short wavelength of light has two implications. One is, that the distance to cross is "many wavelengths" so that even a tiny extinction coefficient is sufficient to cause complete absorption; and the short wavelength means that "everything" in the wall acts as a scattering point, and the light doesn't stand a chance of making it through in measurable quantities.
The following is multiple choice question (with options) to answer.
Sound can travel through the | [
"planet",
"sun",
"body",
"sky"
] | D | sound can travel through air |
OpenBookQA | OpenBookQA-635 | thermodynamics, air, buoyancy, gas, lift
The "why":
Simply put, I'm just wondering if there could be a way of making floating platforms to lift rockets, so they don't need their first stage. Or, at least, to make Zeppelins (a dirigible with rigid structure) to be smaller than conventional helium/hydrogen Zeppelins (but even so, I doubt it).
Of course, I can imagine that if such thing was even efficient, nations would already be using that. You will not get a huge advantage by heating the gas, after all you would need to carry the considerable weight of the heater. Even at very high altitudes, provided the gas inside the balloon is not at a higher pressure than the surrounding air, due to the tension in the balloon envelope, the ratio of the weight of the displaced air causing the buoyancy, to that of the gas inside the balloon will be the same as at ground level.
The net buoyancy is the weight of the displaced air minus that of the internal gas, envelope and payload combined. So the real limit on the ability to gain altitude is the weight of the envelope and payload. When the gasses both inside and outside the balloon are rarefied, you need an envelope of enormous surface area, so it needs to be incredibly thin and light. Perhaps you need graphene for the next world record.
The following is multiple choice question (with options) to answer.
Rocket engines can lift rockets because | [
"of how much fuel they use",
"of how fast they are",
"of the power the hit the ground with",
"of how tall they are"
] | C | a rocket engine is used to produce thrust by pushing gases out at a high speed |
OpenBookQA | OpenBookQA-636 | atomic-physics, history, brownian-motion
Step 2) Because we know pollen is a particle -> sugar must be a particle also
So then why not just measure the osmotic pressure of pollen and then the proof is done? Well I think the problem is that the osmotic pressure is going to be so tiny its undetectable. So back to step 1, he had to find a roundabout way to calculate osmotic pressure, thus kicking off the whole diffusion, random walk statistical analysis which ultimately culminates in Avogadro's constant. Since the same constant governs pollen and sugar, step 2 follows.
Btw I know this is not mathematical proof. Step 2 is not a hard corollary of step 1. To reiterate my key point, Einstein's analysis was not to say anything about the molecular nature of the liquid. It was merely showing that random motion of large particles and molecules from a solute are governed by the same equations.
The following is multiple choice question (with options) to answer.
When we think of bees, we also think of pollen. This is because bees | [
"sleep in it",
"consume it",
"sell it",
"live in it"
] | B | bees eat pollen |
OpenBookQA | OpenBookQA-637 | evolution, homework
Title: Can someone help me analyze this article? I need to read this article — "Beyond the rainbow" by
Marie-Claire Koschowitz et al., for an exam.
Following are some questions for which I could not figure the answer out after reading.
1) Why does this miniaturization necessitates insulation ? Following is quote from article: "For fast-growing, presumably warm- blooded animals , such miniaturization would only have been possible with sufficient body insulation. "
2) Dinosaurs suppose to have tetrachromacy. The article mentions "dinosaurs were endowed with the highly differentiated color vision of birds". Does this mean Dinosaur's "inherited" their tetrachromacy from birds ? Why does the article mention reptiles before that ? Are birds reptiles ?
3) The article starts talking about how mammals develop fur and lost their highly differentiated color vision because they gave up structural color signaling. What is the direct connection between mammals and the dinosaurs ? I don't see the parallel here....why bring the mammals into the discussion ?
4) What is the connection between pennaceous feather and planar feathers ?
Any or all questions answered is welcome ! Thanks ! I will answer the questions one by one-
Why does this miniaturization necessitates insulation ?
An organism's volume determines the total amount of heat that can be stored. The loss (exchange) of heat between the body and external environment mainly occurs on the skin's surface. Hence, body volume determines how much heat is stored, while body surface determines how fast that heat is dissipated to the environment. Volume increases with a power of three with radius, while surface increases with a power of two. Hence, smaller animals have large surface-to-volume ratios, which decreases rapidly with body size. Hence, small animals will dissipate relatively more heat per unit of time.
Dinosaurs suppose to have tetrachromacy. The article mentions "dinosaurs were endowed with the highly differentiated color vision of birds". Does this mean Dinosaur's "inherited" their tetrachromacy from birds ?
No, birds are the closest living relatives to dinosaurs, and birds can be said to have inherited tetrachromacy from dinosaurs - see the cladogram below.
The following is multiple choice question (with options) to answer.
Over many, many years, the buildup of warmth and pressure can take a dinosaur's remains and change them into something that can | [
"power motorbikes",
"melt the moon",
"build corn",
"butter toast"
] | A | heat and pressure change the remains of prehistoric living things into natural gas |
OpenBookQA | OpenBookQA-638 | meteorology, hypothetical, water, geomythology, flooding
Title: Is a complete global flood physically possible on Earth? Genesis 7:11-20 presents an account of an event which, in 40 days, submerges the entire surface of the earth:
[On] the seventeenth day of the second month — on that day
all the springs of the great deep burst forth, and the
floodgates of the heavens were opened…
For forty days the flood kept coming on the earth… all the high
mountains under the entire heavens were covered. The waters rose
and covered the mountains to a depth of more than fifteen cubits
[6.86 m].
Based on this account, my questions are:
Given the amount of water on Earth (including all the water as liquid, solid, and gas, in all possible places: the atmosphere, the surface, and underground), is there enough water to flood the whole earth until ‘all the high mountains… were covered’?
What is the estimated rainfall intensity based on this description, and how intense is it in comparison with today’s rainfall intensity in tropical areas?
Regardless of the veracity or otherwise of the account, this makes for an interesting thought experiment. there is not enough existing water inside this geosystem IMO for such a thing to occur. Let's see these figures here:
One estimate of global water distribution
Oceans, Seas, & Bays 1,338,000,000 -- 96.54% of all water
this figure means that most of the existing water at the global scale is seawater. Sea floor is quite irregular, with some abyss like pits (ex: Mariana trench), up to low water in shallow sea near continents and islands (See figure). A variable topography overall
The following is multiple choice question (with options) to answer.
Which is an example of the type of body of water that contains the most water on Earth? | [
"Sea of Galilee",
"Sea of Tranquility",
"Caribbean Sea",
"Caspian Sea"
] | C | oceans contains most of earth 's water |
OpenBookQA | OpenBookQA-639 | earth, rotation, temperature
Title: What contributes the most to the seasonal temperature variation? The seasonal temperature is ultimately due to the precession of the Earth around the axis. But what I'm curious about is... is it due more to the side experiencing winter being farther from the sun or is it more due to the fact that the days are shorter and the nights are longer? [ The earth is actually closer to the sun in the Northern hemisphere's winter. The seasonal temperature variation is predominantly due to the angle the earth makes with the sun. In the northern hemisphere in winter the angle is such that the earth is tilted with north pole away from the sun and the sunlight hitting the earth is spread over a much larger area than if it was pointed towards the sun. Due to this tilt the sun is also lower in the sky and has the effect shown in the 2nd figure.
The following is multiple choice question (with options) to answer.
Winter in the Northern Hemisphere means | [
"the Northern Hemisphere is experiencing scorching hot weather",
"the Northern Hemisphere is experiencing daily torrential rain",
"the Southern Hemisphere is experiencing warm sunny days",
"the Southern Hemisphere is experiencing frigid temperatures"
] | C | winter in the Northern Hemisphere is during the summer in the Southern Hemisphere |
OpenBookQA | OpenBookQA-640 | newtonian-mechanics, angular-momentum, conservation-laws, planets
Title: Why are the planets rotating on their own axis? Earth is revolving around sun because of gravity but what causes the earth to rotate itself?
This question has been already asked here, but the answers are like, earth had a collision and it formed moon so it started rotating. But what is it with the case of all other planets?
Every planet is rotating on its own axis that too venus and mercury has no moons, so what caused them rotating? First of all, you must know how the Earth formed. When the Sun first formed by the compression of nebulae matter, the rest of the nebula consisted of quite a few debris, that began to orbit around the sun. These debris eventually clumped together and formed planets. So basically, the particles that make up the Earth were already in motion. As they clumped together, they still retained their velocity, and of course, their angular momentum about the Earth's to be axis. The Earth has been spinning from the day (can I use the word day?) it was created.
Further reading (for the fun of it):
Why does the Earth rotate?
How was the Sun formed?
Angular momentum
The following is multiple choice question (with options) to answer.
Despite what some think, instead around themselves, our planet spins around | [
"pluto",
"the moon",
"the milky way",
"the sun"
] | D | the Earth revolves around the sun |
OpenBookQA | OpenBookQA-641 | human-biology, physiology, respiration, breathing, lungs
Title: Why does hyperventilation make you feel like you need to breathe more? Calm Clinic claims:
"The problem is that hyperventilation makes your body feel like you're not getting enough oxygen. Essentially, it makes you feel like you need to take deeper breaths and take in as much air as possible. This makes all of the symptoms of hyperventilation worse."
As far as I know, the brain controls breathing rate by measuring the amount of carbon dioxide in the blood. So is this true? If so, why? Hyperventilation alone does not cause you to feel that you're not getting enough oxygen. Rather, it's what causes hyperventilation that does that (thus resulting in hyperventilation.)
The Calm Clinic explains this quite well (while only mildly contradicting your quote):
During periods of intense anxiety, the body is sent into a state of fight or flight, when the brain signals to the body that danger is afoot. When this happens, you automatically start breathing quickly, as this oxygenates your blood and prepares your body to respond to a threat by fighting or fleeing. If the threat that has triggered your fight or flight response (whether real or imagined) persists, you’re likely to continue hyperventilating until you start to experience other unpleasant physical symptoms.
The focus of your question is
"...This makes all of the symptoms of hyperventilation worse." [emphasis mine]
You can hyperventilate by breathing too quickly or too deeply; either way, in people without underlying medical disorders, hyperventilation is usually caused by stress/anxiety. Anxiety makes your heart rate increase, and causes a perception of the need for more air (not the actual hyperventilation). It is often accompanied by some degree of chest tightness, which many people reasonable attribute to a problem with their heart. These things tend to cause more stress, so it's a cycle. The symptoms of hyperventilation are dizziness/lightheadedness, tingling in your hands/feet and around your mouth, and more but less common symptoms.
Under normal circumstances, hyperventilation leads to a period of decreased respiratory rate to allow for arterial blood to build up that critical buffer, HCO3.
Dealing with Anxiety Symptoms: Hyperventilation
(written for laypersons)
The following is multiple choice question (with options) to answer.
If I am feeling faint after a lot of activity I can | [
"Use the bathroom",
"Exercise More",
"Eat an Apple",
"Throw a Party"
] | C | having food has a positive impact on an organism 's health |
OpenBookQA | OpenBookQA-642 | • This answer is more intuitive than the @ross's answer, if you fleshed out why it's 8 ways, then 6, etc... this would be a great answer. – user138559 Apr 10 '16 at 22:16
• I think part of the elegance of this answer is that it doesn't require fleshing out. The answer self-fleshes. There is a hidden elegance even in the meaning of the "That's obvious" comment at the beginning. It sound's dismissive. But it's actually descriptive. – Mowzer Apr 11 '16 at 18:43
• Something rubs me the wrong way about "That's obvious". I don't think that language has a place on a Q&A site. If it was obvious, they wouldn't have asked. – JPhi1618 Apr 12 '16 at 14:19
• Telling the question asker "That's obvious" violates the Be nice principle that the Stack Exchange network and community tries to adhere to. You can write an answer without belittling the question asker. If it was obvious, then the question wouldn't be asked. Furthermore, you should flesh out what you mean by your various numbers and how you arrived at them. You just stated "8, then 6, then 4..." which is hard to read and understand. And Mowzer, you should not be encouraging this kind of language or vague answers. – The Anathema Apr 12 '16 at 17:58
• @TheAnathema I agree it took me a minute and to look back at the picture to see why $8,6\ldots$ make sense. I can imagine it'd take longer if you don't 'see it' and the answer doesn't help you arrive at it, except by giving the numbers. I do however agree it is intuitive once you see it. – snulty Apr 13 '16 at 12:15
Looking at the picture, there are 4 phases.
1. Draw the petals
2. Draw the upper stem
3. Draw the leaves
4. Draw the lower stem
Lets label these $A,B,C,D$. Clearly, the total number of ways to draw the flower is simply;
$$Total = A \times B \times C \times D$$
The following is multiple choice question (with options) to answer.
A flower may consider its entire point in living to be | [
"propagating the animal kingdom",
"making new flowers bloom",
"feeding bees and making honey",
"spreading its genetic components around"
] | D | a flower 's purpose is to produce seeds |
OpenBookQA | OpenBookQA-643 | microscopy, fluorescent-microscopy, safety, research-tools
Title: What kind of microscope for ML/biological research? I am a computer science student, focusing on machine learning applications. I have been always interested in biology but I lack any training in it. Now, I had an idea that I could introduce myself to biology more by buying a microscope, and doing some small (still serious, if possible) experiments.
Now, the problem one I am facing is what kind of microscope should I get? Preferred answer would outline what kind of research is possible to do with such and such microscope, and what is the typical price range for the system.
If there are any safety (e.g. does any of the UV leak from fluorescence microscopes?) or ethical concerns I would like to hear about them too. Thanks! This really depends on the application you have in mind. As with other precision instruments there is a huge range of qualities and applications.
If you just want brigth field illumination and look at relatively big things ( approx 100 microns) then you could find something decent for the price you mention if you buy used.
But if you want more complex imaging techniques like confocal microscopy or fluorescence microscopy to image smaler strutures and cell imaging then your budget is probably not enough. There you probably won't get a decent microscope for less than 2500 Euro.
I think you should figure out what you want to do with your instrument not just buy one and then get started.
The following is multiple choice question (with options) to answer.
Microscopes | [
"make tiny atoms look smaller",
"enhance the size of amoebas for easier viewing",
"make magnifying things much more difficult",
"make huge samples look minuscule"
] | B | magnifying makes seeing small things easier through using a microscope |
OpenBookQA | OpenBookQA-644 | meteorology, snow, radar
Also note that winter precipitation adds an extra complication because the particles are lighter in weight and can thus be blown about more by vertical and horizontal winds. Raindrops (and hail) are quite likely to fall unless extreme updrafts exist because they are heavy. But drizzle, snow, and sleet may be blown around quite a bit. Without a time-intensive dual-Doppler analysis, you cannot know the wind motion in the storm thoroughly, and therefore will have varying results at times.
And finally, the big wrench is unfortunate inherent to how radars work. They measure the percentage of their sent energy that is reflected back to them. That's great because that's directly connected to the diameter of the item falling (to the 6th power). But unfortunately the grand problem is that in a storm, there is a huge variety of drop/flake sizes mixed together at once... such that we can't extract which combination of particle sizes created it (and thus can't calculate volume to actually know the rain/snow amount that falls). It could be like 6 medium size flakes causing the 10 dBZ echo... or 2 large flakes and 10 small flakes... and each combination is a different volume/snow total. (to see the nitty-gritty math details on this, read more here.) So we can never know for sure the exact rain/snow falling using just radar. The good news is we've at least done lots of experiments and come up with some fairly useful best-practice formulas for using the Z-R ratio in different scenarios. Good, but not perfect.
The following is multiple choice question (with options) to answer.
If a snow storm is coming you should? | [
"Go out",
"Find pizza",
"Buy supplies",
"Watch Tv"
] | C | preparing for a storm requires predicting the occurrence of that storm |
OpenBookQA | OpenBookQA-645 | electrical, fire, polyethylene
My hypothesis is that the static buildup is being caused by friction of the foam with the surrounding air, at a rate that is faster than its ability to release it through the shaft (its only contact with ground).
Questions:
Shall I discard the idea that the static buildup is being caused by friction between layers of the foam in the roll (as they're the same material, theoretically they're not apart in the triboelectric series)?
Other than spraying the area (or even the foam) with any watery solution to increase the conductivity of the air, what would you suggest to keep the sparks from jolting and causing fires?
2A. If a watery solution spray is the best solution there is, what makes a good mixture?
2B. Would a metallic side plate in contact with the shaft and the side of the roll be a good, safe solution? If so, what material would you use?
How could I measure the static electricity built up into the roll to ascertain a "safe limit"? Since asking the question I went to study the subject a little bit more. I want to share my conclusions, hoping that they could be of help to someone else.
Static buildup can't be caused by friction (or contact) between layers of the same material. They don't make a triboelectric pair. Most likely, the static is being generated by the foam slipping in the surrounding air.
This brings us to the second point: try to humidify the air. That could be accomplished by spraying the area, but more technically by installing humidifiers.
In addition to installing the side plate you mentioned (a good conductor, such as copper is the obvious pick, as it doesn't require any mechanical properties), it's a good idea to ensure that the chassis of the rolling machine is properly grounded (as well as those structures in which the material slips).
The following is multiple choice question (with options) to answer.
what causes deposition | [
"electricity conduction",
"earth displacement",
"atomic explosions",
"condensation"
] | B | erosion causes deposition |
OpenBookQA | OpenBookQA-646 | ## A number of people shared a meal, intending to divide the cost evenly among themselves. However, several of the diners
##### This topic has expert replies
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### A number of people shared a meal, intending to divide the cost evenly among themselves. However, several of the diners
by Vincen » Sat Nov 27, 2021 4:38 am
00:00
A
B
C
D
E
## Global Stats
A number of people shared a meal, intending to divide the cost evenly among themselves. However, several of the diners left without paying. When the cost was divided evenly among the remaining diners, each remaining person paid $$\12$$ more than he or she would have if all diners had contributed equally. Was the total cost of the meal, in dollars, an integer?
(1) Four people left without paying.
(2) Ten people in total shared the meal.
Source: Veritas Prep
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### Re: A number of people shared a meal, intending to divide the cost evenly among themselves. However, several of the dine
by [email protected] » Sat Nov 27, 2021 7:31 am
00:00
A
B
C
D
E
## Global Stats
Vincen wrote:
Sat Nov 27, 2021 4:38 am
A number of people shared a meal, intending to divide the cost evenly among themselves. However, several of the diners left without paying. When the cost was divided evenly among the remaining diners, each remaining person paid $$\12$$ more than he or she would have if all diners had contributed equally. Was the total cost of the meal, in dollars, an integer?
(1) Four people left without paying.
(2) Ten people in total shared the meal.
Source: Veritas Prep
Target question: Was the total cost of the meal, in dollars, an integer?
This is a great candidate for rephrasing the target question
The following is multiple choice question (with options) to answer.
Humans are able to eat | [
"only meat products and byproducts",
"exclusively grains and fruits",
"a full assortment of food groups including meat, grains, and vegetables",
"sea life and only green vegetables"
] | C | omnivores eat plants |
OpenBookQA | OpenBookQA-647 | vision, cognition, cat
general reading.
visual cortex of monkeys and cats.
Activation of the hypothalamic feeding centre upon visual prey detection
other research.
The following is multiple choice question (with options) to answer.
An animal's brain | [
"acts as a conduit for the lungs",
"acts as a command base for the body",
"lacks the ability to use spacial reasoning",
"only assists in movements"
] | B | an animal 's brain controls that animal |
OpenBookQA | OpenBookQA-648 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Pollution is | [
"Fish swimming in the sea",
"The wind carrying seeds",
"trees in a forest",
"throwing a gum wrapper in the ocean"
] | D | pollution is when humans pollute the environment with pollutants |
OpenBookQA | OpenBookQA-649 | # related rates help!!!
• November 15th 2007, 04:53 PM
singh1030
related rates help!!!
At noon, ship A is 125 km east of ship B. Ship A is sailing west at 35 http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif, and ship B is sailing north at 35 http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif. How fast is the distance between the ships changing at 2:00 P.M. in http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif?
• November 15th 2007, 05:35 PM
Soroban
Hello, singh!
Quote:
At noon, ship A is 125 km east of ship B.
Ship A is sailing west at 35 km/hr, and ship B is sailing north at 35 km/hr.
How fast is the distance between the ships changing at 2:00 P.M.?
I hope you made a sketch . . .
Code:
B * | \ | \ | \ 35t | \ x | \ | \ | \ * - - - - - - - * - - - - - - * Q 125-35t A 35t P : - - - - - - 125 - - - - - - :
At noon, ship A is at point P.
In $t$ hours, it has moved 35t km to point A.
Then: $AP \:=\:x$, and $QA \:=\:125-35t$
At noon, ship B is at point Q.
In $t$ hours, it has moved 35t km to point B.
Their distance is: . $x \;=\;\sqrt{(125-35t)^2 + (35t)^2}$
So we have: . $x \;=\;\left(2450t^2 - 8750t + 15,625)^{\frac{1}{2}}$
Can you finish the problem?
• November 15th 2007, 05:39 PM
poofighter
The following is multiple choice question (with options) to answer.
The further a ship sails away from a light house | [
"the less they will be guided by it's beam",
"the more they will be guided by it's beam",
"the more likely the ship is to sail successfully",
"rough ocean waters will decrease"
] | A | as distance from a source of light increases , that source of light will appear dimmer |
OpenBookQA | OpenBookQA-650 | java, performance, json, memory-optimization
private boolean isConsecutive(LocalDate date1, LocalDate date2) {
return DAYS.between(date1,date2) == 1;
}
public static <T> void tupleIterator(Iterable<T> iterable, BiConsumer<T, T> consumer) {
Iterator<T> it = iterable.iterator();
if(!it.hasNext()) return;
T first = it.next();
while(it.hasNext()) {
T next = it.next();
consumer.accept(first, next);
first = next;
}
}
}
The following is multiple choice question (with options) to answer.
Being able to enjoy eating Mideastern dates in a small town in the USA is possible because | [
"transporting food became easier, cheaper, and quicker",
"transporting food pays better",
"transported food tastes great",
"fresh food is better than transported food"
] | A | as ability to transport food increases around the world , the available types of food in distant locations will increase |
OpenBookQA | OpenBookQA-651 | predators (y2) die of natural causes (Reaction 3). At the same time , a trio of coming-of-age Predators have arrived to collect the skulls of the aliens as trophies , and the humans are caught between a deadly battle between the Spectacular and decent Aliens/Predators movie set in Antarctica where a motley group takes on extraterrestrial monsters. In The Lotka Volterra Predator-prey Model, The Changes In The Predator Population Y And The Prey Population X Are Described By The Following Equations: Δxt=xt+1−xt=axt−bxtyt Δyt=yt+1−yt=cxtyt−dyt Write A Function Simulatepredatorprey (x,y, A,b,c,d, T) That Takes In The Initial Population This problem has been solved!. The main objective was to investigate the spatio-temporal pattern of diffusive prey-predator model and the emergence of irregular chaotic pattern as a result of prey-predator interaction. Eigenvalues and eigenvectors. This project results in a Lotka-Volterra model which simulates the dynamics of the predator-prey relationship. In this study, the approximate solutions of the predator–prey system with delay have been obtained by using the modified Chebyshev collocation method. To understand how predators optimize foraging strategies, extensive knowledge of predator behavior and prey distribution is needed. The number of predators is represented by y, the number of prey by x. Yang, Yong S. (This Malthus-type equation gives. a discrete time predator prey model specified by Neubert et al[9] which utilises the Ricker model to simulate prey growth. Open the first file for this module by typing on the Matlab command line: ppmodel1. 1 Introduction. If algae and plankton communities are threatened, the entire food web may change. In this work, we investigate numerically a system of partial differential equations that describes the interactions between populations of predators and preys. This paper investigates a dynamical predator-prey interaction model that incorporates: (a) hunting cooperation among predators; (b) Allee effect in prey. At the other extreme,. b) The rabbits eat grass and breed. function to be a Di erence sequence and study the convergence of the model. (5 stars rating will be given =). In the notes, the author
The following is multiple choice question (with options) to answer.
What is an example of predators eating prey? | [
"a boa constrictor devouring a monkey",
"a horse trampling a mouse",
"a cat eating a piece of grass",
"a whale eating tons of algae"
] | A | predators eat prey |
OpenBookQA | OpenBookQA-652 | organic-chemistry
Title: What are the minimal chemical requirements for a food which we all can eat? I've been puzzled by the following though experiment for the past few days:
I want to make my own food from scratch, but I do not know where to start from.
I want to be 100% sure that what I eat will never contains something that can damage my body. For example: If you buy something from the local market you can not be 100% sure that it's safe to eat. (99.9 % maybe... but that's not 100%)
I want to ask you to tell me, how can I make a food that I can eat, or should I say - live on it, for the rest of my life, that's 100% safe, I can control every aspect of it's creation and has many combinations of taste because I love diversity.
Thank you for your time : )
Edit:
Because I realized my question is very broad and indeed is a little... too much scientific I want to close it. But before I do so, here's what I had in mind:
I wanted to take some chemical elements, put them in a jar, run some electricity, heat, whatever through it, filter it, do some additional processing and eat it.
I wanted to know if the stomach can take it, because I was going to eat food that's not hard to digest. Considering the three basic biomolecules used by the body are carbohydrates, lipids, and proteins, you would need to consume these three molecules only. Now we can choose three substances.
Glucose, one of the most basic carbohydrates, is needed for ATP production, so that would be a food choice there.
Any oil or butter will provide lipids.
Protein comes from a variety of sources. Meat is typically though of as the best, but nuts are a pretty good source too.
Since nuts satisfy proteins and lipids, I'd say honey roasted peanuts are the most basic food you could live off of, if you replace pure glucose for the honey.
The following is multiple choice question (with options) to answer.
which one of these would be most nourished? | [
"a person who eats once daily",
"a person fasting all day",
"a person who only drinks water",
"a person who feeds thrice daily"
] | D | an animal needs to eat food for nutrients |
OpenBookQA | OpenBookQA-653 | acoustics
Title: Car horn in the cold I live in Chicago, where it is EXTREMELY cold right now. A couple of mornings ago it was -20C in the morning, and as I was driving through a parking lot a car pulled out of a space right in front of me. I swerved and hit the horn hard to warn the other driver. Fortunately I managed to avoid a collision, however, my car horn did not make a sound. Nothing, nada.
As I was driving to work, after the engine and car had warmed up, all of a sudden the horn started working again.
The fact that it worked tells me there was not a connection problem or such. The only variable was the temperature, but I can't understand why warm air would vibrate, and cold air wouldn't.
Can anyone offer an explanation? Car horn switches are not hermetically sealed or moisture free (unlike some relays found in cars - experience). Assuming your switch/button horn activator had previously fallen below dew point and moisture had condensed on it's contact surfaces and subsequently frozen - ice is not a good conductor of electricity and thus the horn didn't work. Horn switches are normally of the direct push type pressing contacts together on one axis.
Indicators (turn signal) switches are normally of the sliding sort and thus to some extent self cleaning, this is also true of the Tail and headlight switch in my car, perhaps in yours too, thus they are more likely to work first time.
As an experiment, the next time the morning is frosty, you could try pressing the horn repeatedly and hard, this should transfer enough heat energy to de-frost on the contacts and make it work. If this is not effective then an assumption about the diaphragm of the horn being less flexible at frosty temperatures, or the voltage supplied not being sufficient - because you had just started the car (using more than a few amps, starter motors are very power hungry), turned on the lights, rear window demister circuit etc. and the voltage in the battery/alternator circuit had not recovered to one sufficient to make it work.
These are all speculative to some extent, without making specific measurements regarding resistances and voltages, and moisture levels the previous day and of course temperature; it is difficult to do anything other than speculate.
The following is multiple choice question (with options) to answer.
The doorbell was pushed, but sound failed to emit. What might cause this? | [
"atmospheric pressure",
"Batteries dead",
"storm",
"temperature"
] | B | a doorbell converts electrical energy into sound |
OpenBookQA | OpenBookQA-654 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
Since June is cold and wet in Australia, it makes sense that at the same time | [
"Michigan would experience a heat wave",
"Florida would be raining",
"winter would be raging in Colorado",
"everywhere in the world is cold"
] | A | June is during the winter in the southern hemisphere |
OpenBookQA | OpenBookQA-655 | 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.
which of these would you most likely find in a log with a hole in it? | [
"a fish with large gills",
"a dinosaur from the Jurassic era",
"none of these",
"a small sized raccoon"
] | D | some raccoons live in hollow logs |
OpenBookQA | OpenBookQA-656 | optics, geometric-optics, lenses
I found a hand magnifier whose focal length was approximately $5$ cm and set it up to be about $4$ cm from the lens so that the virtual image would be about 25 cm from the lens.
I then put another grid 25 cm from the lens as shown in the photograph.
What was pleasing was that the iPhone simultaneously brought into focus the grid viewed through the lens and the grid 25 cm below the lens.
Note that the grid 4 cm from the lens was out of focus and "bigger" than the grid 25 cm from the lens.
If I had used that as my direct view grid as the reference the magnification found would have been in error.
10 magnified small squares were equal to 63 unmagnified small squares which gave a magnification of approximately $6$ which is not bad when compared with the theoretical value of $\frac {25}{4} \approx 6$.
So perhaps it is worth having another go at measuring the magnification of your $12$ cm lens noting that it is not only the focal length but the optical configuration which determines the magnification?
Later
The magnification $M$ of a magnifying glass is defined as
$$M = \dfrac{\text{angle subtended by image of object when 25 cm from the lens}}{\text{angle subtended by object when 25 cm from the naked eye}} = \dfrac {\alpha '}{\alpha}$$
The HyperPhysics article Simple Magnifier gives some more theory.
The following is multiple choice question (with options) to answer.
Magnifying makes it easier to see a | [
"whale",
"tree",
"bear",
"shrimp"
] | D | magnifying makes seeing small things easier through using a microscope |
OpenBookQA | OpenBookQA-657 | visible-light
Title: How does a flashlight work? How would that be effected in the vacuum of space or on another planet? I was wondering if it was possible to explore the dark side of the moon. I've been trying to figure out a light source so things there can be seen. What we call the "dark side" of the moon is just the side that is not visible from Earth. That side is illuminated by the sun just as often as the side that we can see. But when it is in the light, we don't see it.
As for your other question: conventional flashlights work by sending a current through a light source (incandescent bulb, or these days increasingly LEDs). Either of these will work fine in vacuum.
The following is multiple choice question (with options) to answer.
Flashlights run on batteries in order to light up. Those use chemical energy, light uses | [
"mechanical energy",
"Light energy",
"Hyper energy",
"solar energy"
] | B | a flashlight converts chemical energy into light energy |
OpenBookQA | OpenBookQA-658 | thermodynamics, energy, home-experiment
Note 3: Peak hours tend to be during the day (this may reverse if we get wide-spread solar energy), so keeping the house cool during the day would cost even more. You pretty much have it right. We have two scenarios:
1 - Leave air conditioning on all day. Say that outside temperature is 90 degrees and inside temperature is 70 degrees. Then, all day long, the air conditioning has to remove any heat that gets into the house continuously. Heat transfer depends on the difference in temperature between outside and inside the house. In this case, heat transfer per unit time is equal to a constant K times 20 degrees. Over a whole day of D units of time, the total energy removed by the air conditioner is $20KD$ This assumes that convection (ie air draft) can be neglected.
2 - Stop the air conditioning during the day. If you stop the air conditioning, the flow of heat in the house initially will be the same. However, as time goes by, the inside temperature will increase. This will gradually reduce heat flow as it is proportional to the difference in temperatures. If the house is small enough and badly insulated, you could even get to a point where the inside temperature is equal to the outside temperature, at which point no more heat enters the house. When you get back from work, or if you have a timer a bit before, air conditioning is restarted. You now have to remove all the accumulated heat. However, since less heat entered the house over the duration of the day than if you had kept the air conditioning on, you have less work to do to cool down the house. Yes, the heat will have accumulated in insulation, furniture, walls, etc, but it doesn't matter. There is less heat total to remove.
The following is multiple choice question (with options) to answer.
A person wants to conduct thermal energy through his house, so when deciding on construction materials, he chooses | [
"bits of nickel",
"a wooden beam",
"a plastic shelf",
"a rubber mat"
] | A | a thermal conductor is made of materials that conduct thermal energy |
OpenBookQA | OpenBookQA-659 | 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.
An example of an instinctive behavior is | [
"a herd of zebras heading in the direction of rain clouds at the end of the dry season",
"a baby bird falling from its nest",
"a horse following the commands of its rider",
"a bird dying from an infection"
] | A | migration is an instinctive behavior |
OpenBookQA | OpenBookQA-660 | light, jupiter, natural-satellites, life, europa
Title: Is there enough light to grow plants in the ocean of Europa? What is the underwater temperature of Europa?
I know Jupiter emits infrared light but does it emit any light able to support plant life of any type on near by Moons? Can under water volcanic activity of Europa produce enough light to support plant life? The surface of Europa gets some sunlight direct from the sun and some long wave radiation from Jupiter so it's not in darkness. It's also in Jupiter's radiation belt so it gets hit with high energy charged particles and the surface of Europa, despite being bombarded by particles is still a vacuum. The surface of Europa is a terrible place to look for life, with the exception being that the liquid ocean of Europa explodes onto it's surface regularly, so evidence of life, if it exists, may well be found on the surface, but it's unlikely that anything can live there for long. It's very inhospitable.
The inside of Europa is more interesting. That's why Neil deGrass Tyson says he wants to go "ice fishing on Europa" to see what "licks the camera" and if we find life there we'll "Call them Europeans" . . . funny comments aside, the inside of Europa is probably dark, outside of some infra-red rays due to temperature. Photosynthesis doesn't work well in darkness and with just long wave light, though maybe it's possible, it wouldn't nearly as much growth due to far lower energy levels.
As noted in the answer to your other question, if there is life in Europa's ocean, it's more likely to be something like chemotrophs.
What makes Europa interesting is the energy it gets from tidal forces being stretched between Jupiter and Ganymede, so it gets a regular influx of heat and perhaps internal volcanism, so it may have undersea vents similar to our oceans. The energy influx and possibility of underwater volcanoes makes it more interesting than most other moons or dwarf planets.
If life is found in Europa's oceans, even if it's very primitive life by most standards, it would still be a very cool discovery because it could tell us something about how life starts and that's a big unknown right now. The discovery of life outside the Earth would be a very big story.
The following is multiple choice question (with options) to answer.
Light produced by deep sea animals is used for? | [
"Navigation",
"Camouflage",
"Sexual Display",
"Catching Pray"
] | D | producing light is used for attracting prey by some deep sea animals |
OpenBookQA | OpenBookQA-661 | thermodynamics
Also, if anyone thinks the scoop is going to explode, please mention that too.
Thanks!
*I don't want to use ice because it will water down the coffee. I don't want to use coffee ice cubes because I'm lazy and also I don't have room in my freezer for an extra tray. I don't want to use metal ice cubes or Coffee Joulies™ or stuff that I have to fish out of my glass because, well just because. I don't want to buy a cold plate like for beer kegs. Let's just go with the premise. TLDR; Get a heavy mug and chill it.
The paraffin in the scoop is functioning as a heat capacitor more than a heat conductor. A solid aluminum scoop of the same dimensions would conduct heat almost as well for large temperature gradients, and better for small temperature gradients (the difference here is whether the temperature gradient can drive significant convective flow). When you first put the scoop in the coffee, the convection will be going like crazy, but my estimation below makes me suspect that the temperature gradient will have become very small before the coffee reaches the desired temperature. It sounds to me like you are looking for a method to reach your desired temperature very quickly, so I will ignore heat exchange with the surroundings, which occurs more slowly.
To simplify the math, lets say you are cooling the coffee from 100 degrees C and the scoop is initially chilled to 0 degrees C. Lets also assume that there is 200 g of coffee, 100 g of aluminum, and 50 g of paraffin (I have the scoop you linked and weighed it). The heat capacity of the paraffin is about 2.5 J/gK, that of the aluminum is about 0.9 J/gK while that of the coffee is about 4.1 J/gK. So without exchanging heat with the surroundings, the system will reach a temperature of about 79 degrees C. That's progress, but it's still pretty hot!
The following is multiple choice question (with options) to answer.
A way to keep a cup of coffee warm is to | [
"cook it in the oven",
"heat it with a torch",
"put it in the sun",
"use a heated plate"
] | D | a hot plate is a source of heat |
OpenBookQA | OpenBookQA-662 | evolution, mathematical-models, evolutionary-game-theory
if you are groomed you win 1, if you are groomed, but you don't have to groom - even better win 3 (say)
If you groom but are not groomed, lose 3
If neither of you are groomed, you both lose 1
one might argue the exact proportions, but the point is that getting some thing for nothing is better than reciprocating, and getting nothing for your efforts and time are a loss, because you could have been getting groomed by someone else. As you can see cheaters end up in the top row all the time. grudgers end up along the diagonal, and once in a while in the lower left, Suckers get stuck in the lower left a lot whenever there is a cheater around.
now run this encounter over and over. A behavior which scores negative the more times you run is not stable - they are going to disappear from the population, at least if this disadvantage is real
It has more than one stable outcomes in populations, a population that is full of Grudgers will all groom each other as before you know everyone, you assume they will reciprocate. Everyone wins!
Any invading Cheaters will quickly be at a disadvantage, in that they will not be groomed more than N times where N is the number of grudgers in the community. Note that there is an equilibrium here - the Cheaters may exist in a small number - when N is large enough for a cheater to get enough grooming to make a 'living'.
Suckers can also exist within a population of grudgers, but a population of Suckers where Cheaters show up are quickly sucked dry by the cheaters over several generations where you tally up 'points' and give more, healthier offspring to high scorers. They are not ESS stable.
Cheaters are also stable - nobody ever wins, but they don't lose big either and any invading grudgers can't get groomed.
The following is multiple choice question (with options) to answer.
Abusive relationships often lead to the abused in | [
"future good relationships",
"in favorable outcomes",
"future bad relationships",
"in ideal situations"
] | C | harming something has a negative impact on that something |
OpenBookQA | OpenBookQA-663 | electricity, electric-circuits, electrons, electric-current, charge
Title: Electrons in an electric circuit , its movement and power delivered Does an electrical appliance convert electrons into its respective work , I mean is electron being consumed by appliance (say bulb ) and then this mass gives us energy.
or the same number of electron , just revolve around the circuit, then from where does power comes from, Electrons have charge and so when there is a potential difference across a circuit, this charge moves through it. In an incandescent light bulb, there is a high resistance, meaning that there are many atoms with which the charges collide, transferring some of their kinetic energy. No electrons are being "consumed" by the light bulb, i.e. the number of electrons in the circuit does not change. The ability of the charges to do work is because of a potential difference, which can be achieved through a number of means, e.g. using voltaic cells or electromagnetic induction.
To gain a better idea of why potential difference moves charges, consider two isolated point charges of opposite charges, one positive and one negative. If you pull the negative charge away from the positive one, you are doing work on it in the form of potential energy, as you are opposing the electric field of the positive charge. If you let go, the negative charge will convert this potential energy into kinetic energy, as it is attracted to the positive test charge. A potential difference across a circuit, albeit simplified, essentially does this – it brings electrons from a higher potential to a lower potential, converting potential energy into the kinetic energy in the process.
The following is multiple choice question (with options) to answer.
Electricity from a power plant lights up a light bulb in a house because | [
"a conductor is unnecessary",
"there is only one conductor",
"a conductor inside the house contacts a conductor outside the house",
"the house is free of conductors"
] | C | if one electrical conductor contacts another electrical conductor then electricity will flow through both conductors |
OpenBookQA | OpenBookQA-664 | solar-eclipse
Title: Can you test solar eclipse glasses with a remote control? By putting solar eclipse glasses directly between a remote control IR emitter and device receiver, could some unsafe glasses be detected? My guess is most fake glasses are just blocking visible light at best, while safe ones should block the IR signal as well. It would not guarantee they are 100% safe, but it might be able to detect bad ones.
I know to check for the ISO logo, cert number, and buy from a reputable vendor recommenced by the American Astronomical Society (which I have). It would still be nice to double check pairs of glasses before giving them out to friends and family. Short answer: No.
Long answer: No. You're testing at a single wavelength. The Sun emits continuously at a variety of wavelengths from deep infrared to far ultraviolet. Testing with a single kind of radiation doesn't tell you much about the filter behavior at the other wavelengths.
Buy from the online vendors that specialize in selling astronomy equipment - the ones that all astronomers buy their gear from. They tend to know the stuff they're selling. The list of vendors on the AAS page is good.
The following is multiple choice question (with options) to answer.
If a person wants to watch the eclipse | [
"it's best to go sans sunglasses",
"it's best to just use a hand as shade",
"it's best to use eye protection",
"it's best to use a telescope"
] | C | looking directly at an eclipse of the Sun causes harm to the eyes |
OpenBookQA | OpenBookQA-665 | paleontology, fossils, desert
Title: Why are many fossils found in deserts? Why are deserts famous for fossils? Is it a coincidence? Some examples:
Giant Catfish Fossil Found in Egyptian Desert
Chile's stunning fossil whale graveyard explained
Giant Dinosaur Fossil Found in Sahara Desert I would contend that the fact that the location is a desert has little to nothing to do in most cases to the existence of fossils at the location. Most of the fossils in the location, at least the ones that make most headlines like major dinosaur deposits, were left there millions of years ago. The fact that a location today is a desert has no indication of what the climate, or even where on the globe that location was 50 or 100 million years ago.
Do not forget about plate tectonics and climate change. One can go to places like the Judith Basin in Montana, a relatively harsh area of North American Bad Lands, desert or near desert like conditions with cold winters and find fields of fossils from animals that are believed to have lived in tropic marshes of in oceans, because at the time those animals lived, what is now Montana was not inland, and was not at a Northern location. Millions of years ago it was an undersea plate, thus it has layers of limestone made from ancient single cell sea creatures and sometimes larger objects that were entrapped and preserved as larger fossils. At other times, those plates rose from the sea floor and homed some of the large creatures, like T-Rex that lived, thrived and sometimes survive as fossils.
Later, that plate move and ended up inland, in what is not North America. Glaciers, wind, and water may have stripped off many layers of deposits and left exposed or close to exposed the layers of interest to fossil hunters. Desert regions tend to be subjected to this type of erosion and exposure making such finds easier. If those same fossils were in and area such as a rich planes area with plentiful plant growth and never subjected to glacial scouring, they could be, and may very well be, right below your feet but under many layers of soil and decaying vegetation, river sediment and other deposits rendering them out of sight and out of reach.
The following is multiple choice question (with options) to answer.
How many lizards live in desert habitats? | [
"all",
"some",
"fifteen",
"none"
] | B | some lizards live in desert habitats |
OpenBookQA | OpenBookQA-666 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
evaporation is the first stage in the what cycle | [
"H2O",
"lunar",
"growth",
"menstrual"
] | A | evaporation is when water is drawn back up into the air in the water cycle |
OpenBookQA | OpenBookQA-667 | visible-light, everyday-life, shadow
This is simple to tackle mathematically. When the sun is directly behind/in front of the turbine, the coordinates of a particular blade are transformed as follows when projected onto the ground:
$$ R(\cos(\theta),\sin(\theta))\mapsto R(\cos(\theta)/\tan(\alpha),\sin(\theta)) $$
as is shown above. The elongation is even greater when the sun is at a horizontal angle with respect to the normal of the blades, but I shall ignore this effect for simplicity.
While the velocity of an actual blade ($R\dot{\theta}$) is constant, its projection has a velocity that depends on the angle $\theta$,
$$ v=R\dot{\theta}\sqrt{\frac{\sin^2(\theta)}{\tan^2(\alpha)}+\cos^2(\theta)} $$
and so it follows that the shadow speed varies.
For example, here is a plot of the relative tangential velocity of the shadow as a function of $\theta$ when the sun is relatively low in the sky ($\alpha=\pi/6$):
The following is multiple choice question (with options) to answer.
As a source of light moves directly overhead of an object , what happens to it's shadow | [
"the object will get brighter",
"the shadow will start to spin",
"the size will decrease",
"the light will lean to one side"
] | C | as a source of light moves directly overhead of an object , the size of the shadow of that object will decrease |
OpenBookQA | OpenBookQA-668 | newtonian-mechanics, reference-frames, friction, home-experiment
Title: Help with the problem of moving two fingers along a yardstick The following problem is taken from an MIT homework assignment:
Hold a yardstick horizontally on your index fingers and slide your
fingers together smoothly. The stick slides first on one finger, then
on the other and it keeps alternating. This was demonstrated in
lectures. Try it for yourself, it’s great fun! Why does this happen?
This question has already been asked elsewhere, but I have a question specifically about the MIT solution:
Let $N_1$ and $F_1$ be the normal and frictional forces for one finger, and let $N_2$ and $F_2$ be the normal and frictional forces for the other finger. The key to understanding this problem is to realize that the fraction of weight supported by each finger can be different. Clearly, the finger closest to the center of the yardstick will bear a larger fraction of the weight and hence will exert a larger normal force on the yardstick.
Imagine starting each finger under a separate end of the yardstick. Initially, each finger shares the weight equally, but as you attempt to move your fingers one of them, say finger 1, starts to slide. (To avoid sliding you would have to start with your fingers exactly the same distance from each end and move with exactly the same speed. Clearly human fingers are not capable of this. And the yardstick itself is too irregular for that precision). Immediately after finger 1 slides, both fingers will share the same weight equally ($N_1 = N_2$) but because the kinetic coefficient of friction is less than the static coefficient the friction on finger 2 is greater than the friction on finger 1. As finger 1 continues to slide in, it will bear more of the weight of the yardstick until $N_1$ is large enough that $F_1 = F_2$. As finger 1 moves in just a bit more, finger 2 will no longer be able to sustain the frictional force from 1, and hence finger 2 will move and finger 1 will stop. The whole procedure will begin again.
The following is multiple choice question (with options) to answer.
If I run my finger across a sheet of plain paper and a sheet of sand paper, which will have greater friction? | [
"the plain paper",
"the sand paper",
"neither has friction",
"the same friction"
] | B | as the roughness of something increases , the friction of that something will increase when its surface moves against another surface |
OpenBookQA | OpenBookQA-669 | 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 calf that dies will eventually | [
"disintegrate",
"fall",
"starve",
"wrinkle"
] | A | dead organisms decay |
OpenBookQA | OpenBookQA-670 | inorganic-chemistry, synthesis, purification
Title: Synthesis of anhydrous sodium tungstate I am interested in preparing an anhydrous sample of sodium tungstate (Na2WO4), which is normally found as the dihydrate. Finding an example of this in literature is proving difficult, I am interested if someone can suggest a preparation method based on prior experience or difficulties I should encounter. Hoermann [1] prepared anhydrous sodium tungstate by melting the 1:1 mix of sodium carbonate and tungsten(VI) oxide (and, subsequently, growing single crystals); alternatively, he proposed prolonged drying of a dihydrate at 100 °C:
$\ce{Na2MoO3}$ und $\ce{Na2WO3}$ sind wasserfrei durch Zusammenschmelzen von 1 Mol $\ce{Na2CO3}$ mit 1 Mol $\ce{MoO3},$ bzw. $\ce{WO3},$ oder durch volliges Entwassern der Hydrate bei 100° zu erhalten. Die Salze zeigen ansgepragte Polymorphie.
Busey and Keller [2] obtained anhydrous sodium tungstate (reported water content 0.12%) by drying a dihydrate at 200 °C in vacuum. Purity has also been confirmed by Raman spectroscopy and powder x-ray diffraction:
The $\ce{Na2WO4}$ was prepared by heating the dihydrate at 200° in a vacuum.
References
The following is multiple choice question (with options) to answer.
The creation of gypsum from anhydrite is an example of what? | [
"chemical change",
"volcanic activity",
"biological change",
"mechanical change"
] | A | if an object undergoes chemical change then that object will have new chemical properties |
OpenBookQA | OpenBookQA-671 | newtonian-gravity, free-fall
Note - Although Aristotle was partially correct, he was far from the real understanding of Gravity. Galilean Gravity was closer to the truth. Aristotle deduced that heavy objects fall faster because his observation was affected by air resistance, which is not the real cause of heavier objects falling faster. Galileo had already refuted his explanation of gravity, explaining the affect of air resistance on falling bodies. Galilean Gravity was correcter.
Please refer to this answer for a detailed explanation.
The following is multiple choice question (with options) to answer.
Who famously explicated the science of dropping something? | [
"Galileo",
"Newton",
"Einstein",
"Rutherford"
] | B | dropping something causes that something to fall |
OpenBookQA | OpenBookQA-672 | water, atmospheric-science, molecules, humidity
Commentary 3: Physics explanation based on molecule movement will be greatly appreciated. While you are at it - I have a hypothesis why humidity of the atmosphere is seldom 100 %. Water molecules are lighter than nitrogen (or average air) molecules and thus water vapour rises upward due to buoyancy. Depending on the temperature and vicinity of open water surfaces, the rate at which water molecules float upward may be faster than the rate of evaporation, resulting in a temporary steady state where relative humidity is below 100 %. The water vapour in the atmosphere is not lost to the space, however. At some point it cools down so much that it condenses. Thus clouds are made, which float until they can't support their own weight (by whatever means, up-drafts, buoyancy...) at which point the liquid water obeys gravity and falls down again. This greatly enhances evaporation rates while cooling the atmosphere down, and thus relative humidity rises to near 100 % while it's raining. Once the rain is done and the excess water is either absorbed or evaporates again, the cycle starts up again. Water molecules are lost to the upper layers of the atmosphere faster than evaporation can supply them, and thus relative humidity falls below 100 % again. How far below depends on the temperature, major air currents, open bodies of water, and so on. With neither evaporation nor condensation is the system then you can regard the water vapor and the dry air as distinct systems each subject to the same boundary conditions and conclude that they will have the same behavior.
Thus the absolute fraction of water will be the same at both ends and the relative humidity will vary.
The following is multiple choice question (with options) to answer.
The reverse of evaporation in terms of weather phenomena is | [
"cloud formation",
"condensation",
"transpiration",
"precipitation"
] | D | precipitation is when rain fall from clouds to the Earth |
OpenBookQA | OpenBookQA-673 | thermodynamics, temperature, everyday-life, water
Title: Calculating formula prep using thermodynamics I suspect there is a very simple mathematical formula for preparing formula (forgive the pun) that simply mixes a combo of freshly boiled water and room-temp water.
To be specific, if I need to prepare an n mL feed, I would like to:
Mix x mL room temp (r) water + y mL boiling water to get 70°C water
Mix in the scoops of powder
Mix in z mL of room temp water to bring it down to 45°C.
x + y + z should equal n. But I'm struggling to figure out what x, y and z are given r.
Background:
Infant formula requires initially mixing with water at 70°C to kill cronobacter, then bringing it to about 45°C so baby can drink it. Prep guidelines say to boil water, wait for 30 mins till it gets to approx 70°C, add the powder, then rinse the bottle under tap water until it reaches about 45°C. Very imprecise and inefficient with a screaming baby.
As this post says, the heat capacity of water stays almost constant between 0°C to 100°C, therefore (for example) you can mix 30% of 0°C water and 70% of 100°C water and you'll end up with a liquid that is at 70°C, up to a small error. So I'm hoping this kind of calculation could be applied to my problem, albeit with room temp (r) water instead of 0°C.
Additional notes:
The amount of water in the first step should be maximized so the powder can be adequately dissolved.
Approximate results are ok, though we should err on the side of slightly higher than 70°C for the first step and slightly under 45°C for the third, if anything.
Room temperature is a variable to account for different climates.
I guess the addition of powder would cool the result down slightly, but as I mentioned, slightly under 45°C for the final result is ok.
The following is multiple choice question (with options) to answer.
Preparing food at the proper temperatures | [
"is too much work and should be avoided",
"eradicates potential illness causing organisms",
"allows bacteria to flourish",
"leaves meat raw and under cooked"
] | B | cooking food to proper temperatures protects against food poisoning by killing bacteria and viruses |
OpenBookQA | OpenBookQA-674 | astronomy, sun, moon, eclipse
Title: Why don't we see solar and lunar eclipses often? Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Moon at the night and as far as I know if this happens during the day, you'll get to see a solar eclipse. Why don't we get to see this often or in the day?
Does it mean that in some part of world there's a solar eclipse when we are seeing a new moon? I'm looking for a diagram or interactive way to understand this if possible as I'm not a native English speaker, but I'll try my best to do so. If the Moon's orbit around the Earth were in exactly the same plane as the Earth's orbit around the Sun, we'd have a total solar eclipse every month (but 100% totality would be seen only from the tropics).
But in fact they're not in the same plane. The Earth's spin axis is tilted by about 23 degrees relative to the Earth's orbit around the Sun, and the Moon's orbit is closely aligned with the Earth's spin. As a result, the Sun and the Moon do not follow the same path in the sky.
We get a solar eclipse only when (a) there's a new Moon, so the Sun and Moon are in the same position east-to-west, and (b) the new Moon happens when the Sun and Moon happen to be closely aligned north-to-south.
Since the Sun and Moon are both about half a degree wide (as we see them in the sky), the 23-degree offset of their paths makes solar eclipses relatively rare events.
Lunar eclipses, which occur during the full Moon when Moon passes into the Earth's shadow, are more common because the Earth is bigger than the Moon, and so has a much wider shadow.
The following is multiple choice question (with options) to answer.
A new moon can be observed every | [
"1 month",
"1 week",
"1 day",
"1 year."
] | A | a revolution of the moon around the Earth takes 1 month |
OpenBookQA | OpenBookQA-675 | 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.
While robins refuse to eat much aside from insects, worms and fruit, most birds can make a nice meal out of | [
"potato boxes",
"small beds",
"wildflower kernels",
"grass stains"
] | C | birds sometimes eat seeds |
OpenBookQA | OpenBookQA-676 | ethology, mammals, language
Title: Can dolphins actually communicate linguistically? Humans use "language." By language, I mean the thing I am using right now to talk to you.
I know dolphins and orcas have very complex communication systems and also seem to process linguistic and gestural commands.
But do they have their own languages? Where is the evidence for or against? If we take two group of dolphins Group A and Group B, would Group A speak one language and Group B speak another? Dolphins and orcas do have dialects. Of course there are species specific dialects and it has been shown that orcas reared with bottlenose dolphins tend to learn the latter's dialect. Dolphins of the same species also seem to have regional dialects, as mentioned in this BBC post (I personally do not trust in non-research articles much, but nonetheless in this case the article indicates a certain possibility of a phenomenon). However, this page also reports the same finding and this source seems to be much more reliable. There are citations too that are at present inaccessible to me. Both the sources say that bottlenose dolphins from Shannon estuary in Ireland, "speak" different dialect compared to those from Cardigan Bay in Wales.
The actual research work is this:
Hickey, R. (2005) Comparison of whistle repertoire and characteristics between Cardigan Bay and the Shannon estuary
populations of Bottlenose dolphins (Tursiops truncatus) with
implications for passive and active survey techniques. School of
Biological Sciences, University of Wales, Bangor
Apart from having regional dialects, the cetacean communication also seems to have other features of a "language". I am pasting excerpts from this article which basically reports a study on the acoustic communication or codas in sperm whales. This may apply to dolphins as well.
Individuals within social units have preferred associates among
members (Gero et al. 2008), indicating differences in the way an
individual interacts with other members of its unit. These preferred
associations among unit members suggest the possibility of an
individual discrimination system.
The following is multiple choice question (with options) to answer.
A pod of dolphins is swimming while searching for food. The youngest dolphin swims away from the pod and is lost. The rest of the pod searches for the young dolphin by clicking into the water. The young dolphin is found because of | [
"echoes from noise",
"vibrations from drums",
"sound of water",
"movement in air"
] | A | echolocation is when some animals detect objects by hearing echoes by emitting sound |
OpenBookQA | OpenBookQA-677 | paleontology, fossils, desert
Title: Why are many fossils found in deserts? Why are deserts famous for fossils? Is it a coincidence? Some examples:
Giant Catfish Fossil Found in Egyptian Desert
Chile's stunning fossil whale graveyard explained
Giant Dinosaur Fossil Found in Sahara Desert I would contend that the fact that the location is a desert has little to nothing to do in most cases to the existence of fossils at the location. Most of the fossils in the location, at least the ones that make most headlines like major dinosaur deposits, were left there millions of years ago. The fact that a location today is a desert has no indication of what the climate, or even where on the globe that location was 50 or 100 million years ago.
Do not forget about plate tectonics and climate change. One can go to places like the Judith Basin in Montana, a relatively harsh area of North American Bad Lands, desert or near desert like conditions with cold winters and find fields of fossils from animals that are believed to have lived in tropic marshes of in oceans, because at the time those animals lived, what is now Montana was not inland, and was not at a Northern location. Millions of years ago it was an undersea plate, thus it has layers of limestone made from ancient single cell sea creatures and sometimes larger objects that were entrapped and preserved as larger fossils. At other times, those plates rose from the sea floor and homed some of the large creatures, like T-Rex that lived, thrived and sometimes survive as fossils.
Later, that plate move and ended up inland, in what is not North America. Glaciers, wind, and water may have stripped off many layers of deposits and left exposed or close to exposed the layers of interest to fossil hunters. Desert regions tend to be subjected to this type of erosion and exposure making such finds easier. If those same fossils were in and area such as a rich planes area with plentiful plant growth and never subjected to glacial scouring, they could be, and may very well be, right below your feet but under many layers of soil and decaying vegetation, river sediment and other deposits rendering them out of sight and out of reach.
The following is multiple choice question (with options) to answer.
In the desert, the cactus is a rare source of | [
"food",
"shelter",
"moisture",
"shade"
] | C | a cactus stores water |
OpenBookQA | OpenBookQA-678 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
Renewable resources are | [
"provided by the largest star and wind",
"provided by solar and petroleum reserves",
"provided by the sun and fossils",
"provided by the sun and coal"
] | A | solar energy is a renewable resource |
OpenBookQA | OpenBookQA-679 | geography, mantle, crust, mining, cavern
6.Record absolute depth under sea level a person has reached "on foot".
If you consider Vescoso to have been "on foot", he wins again. If not, and you consider miners going to their jobs as being "on foot", then it would be the Canadian miners (2.65 km below see level). If you are strict against both, my first thougth is then maybe port workers (note a submariner won't win in this case neither), or maybe a spelunker, but user Semidiurnal Simon clarifies it on comments. I was wrong (I said I made the estimations quickly) as: "For the strictest "on foot", it won't be port workers, it'll be somebody in a below-sea-level basin (e.g. by the Dead Sea), or possibly a low-altitude mine that has a drift (slanted corridor) entry and so doesn't require an elevator."
7.Record absolute depth under surface by drilling.
Sending machines from the surface (by borehole) rather than humans, the Kola Superdeep Borehole is the deepest (12km).
8.Record closest drill to Earth's Center.
The Ocean Drilling Program could have this record, but I cannot determine where. Average seabed deep rounds -4.000 m. and the Arctic Ocean is not a deep ocean in comparison with the Pacific and Atlantic. So the Kola Borehole may well have this record too.
The following is multiple choice question (with options) to answer.
The ceiling of the cave grew closer to the ground due to: | [
"deposition",
"luck",
"magic",
"wood."
] | A | stalactites are formed by deposition |
OpenBookQA | OpenBookQA-680 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
Do all organisms reproduce uniformly? | [
"they are different",
"they are same",
"they reproduce equally",
"reproduction is fixed"
] | A | different organisms reproduce differently |
OpenBookQA | OpenBookQA-681 | home-experiment, mixtures
Title: What household substances could be distilled I'm looking to experiment with distillation to have a basis for understanding the theory slightly better, and get a better feel for it.
I'm hoping for some suggestions as to what I could try distilling, such as purifying drinking alcohol. Any single idea would be appreciated, best answer would be awarded to an idea where:
The resulting purity would be straight forward to approximately test
No part of the distillation presents a significant hazard (e.g. toxic fumes, high volatility)
No particularly specialist or expensive equipment is required (e.g. extreme temperatures)
I think that pretty much covers it. I'm just looking for one or two ideas which I can experiment with besides alcohol.
Thanks This is tricky. Besides water, nearly everything has some hazard associated with it. And even water distillation involves high temperature (100C). Be careful distilling alcohol: the azeotrope of distilled alcohol is 95% ethanol which is VERY flammable! Plus, technically speaking, distilling alcohol may be illegal where you live.
One thing you could do is distill water with dissolved substances, most likely table salt (NaCl). This would help you test the principle that distillation is a technique for separating substances. In this case, distilling salt water should yield pure water. A more visual example would be brewed coffee or tea, which is a suspension and should separate into water and crud!
And after that, I'd be careful! For example, concentrating acetic acid (white vinegar) is dangerous, as concentrated acetic acid is both corrosive and has choking fumes. I would not even consider trying something that is not food grade, given your requirements.
The following is multiple choice question (with options) to answer.
which one of these could eventually facilitate an intoxicating drink? | [
"a serving of pie",
"all of these",
"a cob of corn",
"a stick of ice cream"
] | C | ethanol sometimes is made of corn |
OpenBookQA | OpenBookQA-682 | evolution, botany, development, fruit, seeds
What is the point of fruit if not to be eaten? It’s my understanding that organisms will adapt to survive and thrive. I understand that being eaten can spread seeds, but this just seems like too much of a risky tactic to rely on.
Following on from part one: If being eaten is the best way to spread seed, why do some plants avoid this (such as by being poisonous or thorny)? Seeds are spread by many mechanisms
Wind dispersal: When air currents used to spread seeds. Often these plants have evolved features to facilitate wind catching, for example dandelions. Aka, anemochory.
Propulsion & bursting: When seeds are propelled from the plant in an such as in these videos. This is called Ballochory.
Water: Similarly to wind dispersal plants can spread seeds by water movement/currents, aka Hydrochory. This is used by many algae and water living plants.
Sticky Seeds: There are many ways a seed can attach to the outside of an animal - by using hooks, barbs, sticky excretions, hairs. Seeds then get carried by an animal and fall off later. This is epizoochory.
Fruiting: Plants can use seed-bearing fruit to encourage animals to eat the seeds. They will then be spread when the waste is excreted after digestion. This is a process of endozoochory.
More than one way to spread a seed
The following is multiple choice question (with options) to answer.
Seeds that stick in the fur of an animal | [
"will hitch a ride on that animal",
"will fall back off immediately",
"will sprout roots in the animal's fur",
"will be unable to regerminate"
] | A | if seeds stick to the fur of an animal then that seed will be transported by the animal |
OpenBookQA | OpenBookQA-683 | thermodynamics, everyday-life
Title: Why do fruits left to dry in the sun feel so much warmer to the touch than other objects outside? I have been putting preserved plums, on a rack, to sun and dry on my balcony. When I take them in at dusk, the plums are noticeably hot to the touch. They feel warmer than the bamboo and metal racks they are on, the cardboard box I put the racks on, the netting I put over the lot, and the air outside. (Note that ambient air temperature doesn't start dropping until well after I have the plums indoors.) The balcony itself, made out of a light-colored concrete-like composite, and the metal railing also feel warm, but not as much as the plums do.
I recall some relevant concepts from physics classes, but I can't tell if I'm taking into account everything at play. Here's what I have so far:
Plums are mostly water, which has a high specific heat (~4 kJ/kg/K) relative to air (~1 kJ/kg/K) and probably the other objects. I'm guessing the balcony also has a higher specific heat than air. Higher specific heat means that by the end of the day, the plums have stored more thermal energy than the cardboard box.
Water and metal are good thermal conductors, so they will feel warmer to my hands than the other objects even if they contain the same energy per unit.
Is there something else in here about the plums converting radiant energy to thermal that the other objects don't, or something about air flow? Is it a sign (which I suppose is not for Physics.SE) of fermentation? You were on track...and then missed the mark.
Higher specific heat means that by the end of the day, the plums have stored more thermal energy than the cardboard box."
Correct. You're on track...
Water and metal are good thermal conductors, so they will feel warmer to my hands than the other objects even if they contain the same energy per unit.
The following is multiple choice question (with options) to answer.
To warm yourself up on a chilly day | [
"rub your palms together",
"wear short sleeve shirts",
"go without any socks",
"stand still in one place"
] | A | friction causes the temperature of an object to increase |
OpenBookQA | OpenBookQA-684 | soil, minerals, terminology, soil-science
Title: "Down wash" as a source for mineral particles in the soil In a previous IGCSE examination paper$^1$, the following question was asked and answer provided:
State one source of mineral particles in soil.
Marking Scheme:
Accept any one of:
rock;
down wash;
What's "down wash" and how is it responsible for providing minerals to soil? Googling the term lead me to an aerodynamics definition, which I doubt is the one referred to by the marking scheme.
$^1$ UCLES. Environmental Management, 0680/12, Paper 1. Cambridge International General Certificate of Secondary Education, February/March 2017. Downwash can be part of some erosion environments where minerals are moved down from their host rock environment to another location.
Black Snake Range - Granite Slopes, Victoria, Australia
The crest of the divide rises to almost 400 metres and at this site there are numerous exposed granite slopes and large boulders near the ridge crest. The lower slopes have a cover of granite downwash and the minor valleys have become partly infilled with this granitic sand wash, and hence they are swampy
Southdowns, UK, page 4
Overlying the bedrock geology are drift deposits of alluvium (along the numerous
streams) and ‘head’ (downwash deposits at the base of the Greensand Hills around
Liss and Petersfield).
In the Discussion section of Slope Stability and Slope Formation in the Flysch Zone of the Vienna Forest (Austria)
The downwash of the basal clays and marls, uncovering the solid bedrock, has to be regarded as the main aspect of this phase
The following is multiple choice question (with options) to answer.
The creation of sediment is produced by | [
"the break down of other materials",
"materials joining together into one",
"solar interaction with the earth",
"chemicals compounds combining together"
] | A | sediment is formed by weathering |
OpenBookQA | OpenBookQA-685 | vision, cognition, cat
general reading.
visual cortex of monkeys and cats.
Activation of the hypothalamic feeding centre upon visual prey detection
other research.
The following is multiple choice question (with options) to answer.
A big cat looks for prey | [
"at 3pm",
"at 11pm",
"at 9am",
"at noon"
] | B | nocturnal predators hunt during the night |
OpenBookQA | OpenBookQA-686 | soft-question, electricity, energy-conservation, visible-light, terminology
Title: Is an electric lamp a transducer? Silly thought.
A transducer, by definition, is a device that converts variations in one form of energy to another. An electric lamp converts electricity into visible light - the brightness may vary depending upon the electric potential applied.
Is it correct to state an Electric Lamp is a transducer? Strictly yes, a transducer converts one form of energy to another. It's more commonly used when you are converting some physical effect into electrical energy as in a sensor.
The following is multiple choice question (with options) to answer.
Lamps that convert electricity into light and heat are known as | [
"incadescent",
"flourescent",
"led",
"candle"
] | A | some light bulbs convert electricity into light and heat energy |
OpenBookQA | OpenBookQA-687 | planet, 9th-planet, kuiper-belt
Title: What type of planetary-mass object would Planet Nine be? Given that Planet Nine is hypothesized to be 10-20 times the mass of the Earth orbiting the sun some 200-2500 AU out, what kind of planetary-mass object would it be?
Even given that it has apparently "influenced" several Trans-Neptunian objects, since its orbit is so large and so slow (approximately 25,000 years) it would take an awful long time to clear out its own orbit (especially given that we do not know how long it has been in that orbit), so it seems like it would not qualify as an actual planet under the rules that re-classified Pluto.
Since it orbits our sun, it wouldn't be an exoplanet nor a rogue planet. And it sure seems too big to be called a dwarf planet.
A captured planet seems closest in other attributes, but it probably was not either a capture nor a re-capture, but more likely a partial ejection.
So what classification would it fall into? It is a planet - either a gas giant core, a mini-Neptune, or a super-Earth.
First off, Mike Brown has stated outright
“It is a planet—there’s virtually no doubt,” he said. “What we now call planets are objects that can gravitationally dominate their neighborhood. Pluto is a slave to the gravitational influence of Neptune. By area, Planet Nine dominates more of the solar system than any other known planet—it’s only because of this that we can infer its existence. And because of this we’re pretty sure it’s not a small object: it’s at least ten times more massive than Earth and five thousand times more massive than Pluto. In many ways, you could argue that this is more of a planet than anything else in the solar system.”
The following is multiple choice question (with options) to answer.
What former planet is yet to clear its orbit? | [
"planet Venus",
"the earth",
"Former seventh planet",
"planet Mars"
] | C | pluto has not cleared its orbit |
OpenBookQA | OpenBookQA-688 | acid-base, aqueous-solution, ph
$$\ce{CN-(aq) + H2O(l) <=> HCN(aq) + OH-(aq)}$$
That's because $\ce{HCN}$ is a very weak acid and its conjugated base a weak base (homework: look up the $K_b$ of $\ce{CN-}$).
Now, as you duly noted, there's excess $\ce{KOH}$ in the solution, which dissociates completely. The $\ce{OH-}$ resulting from that dissociation now push the equilibrium:
$$K_b=\frac{[\ce{HCN}]\times[\ce{OH-}]}{[\ce{CN-}]}$$
to the left. As a result, the contribution of the $[\ce{OH-}]$ coming from the hydrolysis of the cyanide is negligible and can be ignored. Only the $[\ce{OH-}]$ from the excess $\ce{KOH}$ is to be counted. So $[\ce{OH-}]\approx 0.06\ \mathrm{mol/L}$.
We can confirm that numerically by assuming $[\ce{OH-}]\approx 0.06\ \mathrm{mol/L}$ and with:
$$\frac{[\ce{HCN}]}{[\ce{CN-}]}=\frac{K_b}{[\ce{OH-}]}\approx 0.0027$$
So neglibibly little cyanide is present as the acid $\ce{HCN}$.
The following is multiple choice question (with options) to answer.
If a cat is given cyanide, it will | [
"expire",
"cough",
"puke",
"eat"
] | A | poison causes harm to living things |
OpenBookQA | OpenBookQA-689 | newtonian-mechanics, energy-conservation, friction, everyday-life, physical-chemistry
Title: Conservation of energy when we drive a car When we drive a car, we use gasoline as the source of energy. When we arrive at the destination, we lose some of the gasoline, used to move the car from one point to another. Then how energy is conserved, if we spend energy to move the car? What does it mean to "spend energy"? In the concrete example, the engine converts the chemical energy in the gasoline through combustion into kinetic energy of the car.
While the car is moving, it feels friction with the surface and air, so some of the kinetic energy of the car goes into friction (heat, air movement, etc).
When you stop the car, the kinetic energy completely goes into friction in the brakes, asphalt and air (again, as heat or kinetic energy of the air molecules, etc).
Conservation of energy means that in a closed system the energy stays constant. If you look just at the car and not also at the surroundings, that is not a closed system, and that principle is not applicable here. However, you can look at the surroundings too; then it all works out.
The following is multiple choice question (with options) to answer.
The more miles that you can get out of a gallon of gasoline, what happens? | [
"gasoline will take you a lower distance than normally",
"more gasoline sales will be made",
"travel expenses will go up due to gasoline costs",
"less gasoline will be needed to go a distance"
] | D | as mileage per galon of gasoline increases , the amount of gasoline used will decrease |
OpenBookQA | OpenBookQA-690 | optics, geometric-optics, lenses
I found a hand magnifier whose focal length was approximately $5$ cm and set it up to be about $4$ cm from the lens so that the virtual image would be about 25 cm from the lens.
I then put another grid 25 cm from the lens as shown in the photograph.
What was pleasing was that the iPhone simultaneously brought into focus the grid viewed through the lens and the grid 25 cm below the lens.
Note that the grid 4 cm from the lens was out of focus and "bigger" than the grid 25 cm from the lens.
If I had used that as my direct view grid as the reference the magnification found would have been in error.
10 magnified small squares were equal to 63 unmagnified small squares which gave a magnification of approximately $6$ which is not bad when compared with the theoretical value of $\frac {25}{4} \approx 6$.
So perhaps it is worth having another go at measuring the magnification of your $12$ cm lens noting that it is not only the focal length but the optical configuration which determines the magnification?
Later
The magnification $M$ of a magnifying glass is defined as
$$M = \dfrac{\text{angle subtended by image of object when 25 cm from the lens}}{\text{angle subtended by object when 25 cm from the naked eye}} = \dfrac {\alpha '}{\alpha}$$
The HyperPhysics article Simple Magnifier gives some more theory.
The following is multiple choice question (with options) to answer.
A magnifying glass would be useless in viewing? | [
"tadpole",
"ant",
"sand grain",
"elephant"
] | D | magnifying glass is used to see small things by making objects appear bigger |
OpenBookQA | OpenBookQA-691 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
Seasonal changes happens | [
"when some flowers cease to bloom in the cold months",
"when ducks swim more in lakes",
"when fish arise from water and sun themselves",
"when all flowers bloom in the cold months"
] | A | An example of a seasonal change is plants becoming dormant in the winter |
OpenBookQA | OpenBookQA-692 | classical-mechanics, fluid-dynamics, pressure, fluid-statics, weight
Title: Pressure inside when a container is closed Let us suppose that there is a container with its lid open sitting at the bottom of an ocean. The pressure at the bottom of the container will depend on the water column above it assuming only static pressure. Now if I close the lid of the container will the pressure at the bottom of the container reduce? I think it will because the height of the water column has been reduced. The lid supports almost all the weight of the water column above it. I know it's a stupid question but I don't know where I am wrong. Am I missing something?!
Sorry for the bad drawing. P is the required pressure near the bottom of the container after closing the lid. Assume that the pressure is only due to the weight of the water column. We often simplify the pressure at the bottom of a (dense) fluid to be $P = \rho g h$. But this is only the additional pressure at the bottom due to the fluid. If there is pressure at the top of the fluid, that is added in as well.
So the pressure at the bottom is $P_{bottom} = \rho gh + P_{top}$
When you close the lid, the column of fluid in the box is shorter, but the pressure applied to the top of the column is increased due to the rigidity of the lid. The pressure at the bottom remains unchanged.
The following is multiple choice question (with options) to answer.
Where does an object feel the least pressure? | [
"a riverbed",
"a puddle",
"a lake bed",
"the ocean floor"
] | B | as an object descends into water , the pressure on that object will increase |
OpenBookQA | OpenBookQA-693 | ecology, population-dynamics, ecosystem, antipredator-adaptation, predation
I would also like to talk about other things that might be of interest in your model (two of them need you to allow evolutionary processes in your model):
1) lineage selection: predators that eat too much end up disappearing because they caused their preys to get extinct. This hypothesis has nothing to do with some kind of auto-regulation for the good of species. Of course you'd need several species of predators and preys in your model. This kind of hypothesis are usually considered as very unlikely to have any explanatory power.
2) Life-dinner principle. While the wolf runs for its dinner, the rabbit runs for its life. Therefore, there is higher selection pressure on the rabbits which yield the rabbits to run in average slightly faster than wolves. This evolutionary process protects the rabbits from extinction.
3) You may consider..
more than one species of preys or predators
environmental heterogeneity
partial overlapping of distribution ranges between predators and preys
When one species is absent, the model behave just like an exponential model. You might want to make a model of logistic growth for each species by including $K_x$ and $K_y$ the carrying capacity for each species.
Adding a predator (or parasite) to the predator species of interest
... and you might get very different results.
The following is multiple choice question (with options) to answer.
The population of rabbits in an area increases. That could have been caused by | [
"More predators have been moving into the area",
"The rabbits are becoming infertile",
"Hunters are trapping the rabbits",
"More precipitation falling lately"
] | D | as the available water in an environment increases , the populations of organisms in that environment will increase |
OpenBookQA | OpenBookQA-694 | human-biology, reproduction
Title: Why are animal births not taken as seriously as human births? When humans give birth, more than often medical assistance is needed. Others gather around and frantically look for any way to help. But when an animal gives birth, it is usually seen as a moment where you give the female its space and let the birth occur naturally and without any assistance. The animal is of course in serious pain just as a female human but this is more than often not taken into account. Why is it that animal births are not taken as seriously? Our heads are bigger.
There's some debate on the issue, but in essence, human brains, and therefore heads, are very large relative to our body size. This is handy for all the intelligent things we like to do, but can be rather painful during birth. Because we walk upright, the size of a newborn's head is actually a non-trivial fact during the birthing process. There are two major implications.
The first is that human birth hurts. You can watch the birth of other animals and they seem to brush it off, but for humans, forcing that huge head through a relatively small birth canal is difficult. Evolution has (supposedly) limited the size of the hips because, while that would allow an easier birthing process, it would negatively impact our ability to walk. As such, it has to hurt.
Secondly, in order to make the process easier, humans rotate during birth. The end result is that, unlike even other closely related primates, humans come out backward in a way that is very difficult for a birthing female to attend to. This almost requires having another person or two on hand to help out. This would, of course, be a huge reinforcement for social connections.
A few books I know of touch on this. Up From Dragons deals with the brain size/hip size issue and The Invisible Sex talks about rotation during the birthing process and the social implications.
The following is multiple choice question (with options) to answer.
Humans are like monkeys in a lot of ways, besides sharing a lot of the same DNA, their babies are birthed | [
"mad",
"old",
"alive",
"dead"
] | C | a monkey births live young |
OpenBookQA | OpenBookQA-695 | photosynthesis
Title: What vegetation would thrive in the Martian atmosphere? Most plants require carbon dioxide for their photosynthesis, which Mars has in overabundance.
Would atmosphere composition (let's ignore temperatures for the purpose of this question) of Mars allow vegetation to grow? This is not my field by a long shot, so take what I say with a grain of salt. However, this question is very hard to answer because whether or not a plant will grow depends on a great variety of factors. Even if we ignore the temperature as you say, there are other considerations. These include, but are not limited to:
Soil composition, I doubt that Martian soil can support earth vegetation even if its atmosphere could. Plants need various nutrients, and specific pH ranges among other things.
Atmospheric pressure, I am not at all sure that the Martian atmosphere (though it is, indeed rich in CO2) would be enough to drive an earth plant's photosynthesis. Bear in mind that the atmospheric pressure on Mars averages 600 pascals (0.087 psi), about 0.6% of Earth's mean sea level pressure (source). This makes it highly unlikely that unmodified earth plants would be able to thrive there.
Water water water...
Pollinating species. Many many plants depend on other species (e.g. bees or hummingbirds) for their propagation. These would be hard to find on Mars.
Sunlight I don't know if Mars receives enough sunlight at its distance from the sun to drive an unmodified plant's photosynthesis.
Now, that said, it should theoretically be possible to start with some extremophile archaea or bacteria that would over the course of many many many years (at least hundreds, thousands more probably) terraform Mars to make it suitable for human habitation. Specially engineered plants could play a role then but I find it very hard to believe that any existing, unmodified, multicellular plant life of earth origin could survive on Mars.
The following is multiple choice question (with options) to answer.
Environments like the rain forest have such an abundance of flowers and plants due to the amount of what, which is needed for vegetation to thrive? | [
"Sunlight",
"water",
"Animals",
"people"
] | B | a plant requires water to grow |
OpenBookQA | OpenBookQA-696 | thermodynamics, thermal-conduction, thermal-insulation
Compress the fleece thinner so there is less air volume. The acrylic will conduct better than the captured air.
Replace the air with a more conductive fluid like water, or oil, or thermal grease containing conductive metal powder.
Instead of using acrylic polymer for the fibers, fill or replace them with a more conductive material.
Design the material to have larger pockets that allows more internal convective currents.
Use black and darker colors as they have higher emissivity.
The following is multiple choice question (with options) to answer.
To aid in keeping your outdoor animals warm in the winter | [
"put their shelters directly in the way of the wind",
"put their shelters on top of cement",
"attach thermal insulators to their shelters",
"attach shingles to their shelters"
] | C | a thermal insulator slows the transfer of heat |
OpenBookQA | OpenBookQA-697 | metabolism, ecology, photosynthesis
Title: Why isn't phosphorus or nitrogen a limiting nutrient for animals? Nitrogen and Phosphorus are usually the limiting nutrient for plants, especially for algae. Phosphorus is used for DNA, ATP and phospholipids, and Nitrogen is used for pretty much every protein a cell might want to produce. That is, their need for biological processes is not tied specifically to photosynthesis: anything that lives is going to need them, pretty much for anything it might want to do. It would make sense for them to be a limiting nutrient for almost anything that's trying to grow, plant or animal.
Yet for animals the limiting "nutrient" seems to always be energy, ie: food. Why aren't animals limited by lack of nutrients in the same way that plants are? Obviously animals need these nutrients, too. Or to reverse the question, why do plants need so much more phosphorus/nitrogen than animals do?
My best guess is that an animal's digestion of plant material is relatively inefficient energy-wise but relatively efficient nutrient-wise. So for an animal to eat enough food to have sufficient energy to survive, it's probably eaten more than enough Nitrogen and Phosphorus for its needs. But I'm just guessing and I can't find any data that would back up that guess. Phosphorus
Your suggestion that if we are meeting our calorific requirement we will be getting enough is true for phosphorus.
Most foods contain lots of phosphorus. The maximum dietary requirement occurs during adolescent growth, estimated at 1250 mg per day. Assuming a calorie intake of 2500 kcal we can calculate a 2500 kcal equivalent phosphorus content for various foods:
skimmed milk contains 7,400 mg phosphorus per 2500 kcal
roasted chicken breast contains 7,500 mg phosphorus per 2500 kcal
cooked white rice contains 3840 mg per 2500 kcal
(Calculations are based upon values obtained via this site.)
Nitrogen
Our requirement for nitrogen is met by our protein intake: inadequate protein intake manifests as kwashiorkor which is essentially due to a dietary deficiency of essential amino acids. In other words, the only way to achieve a nitrogen-deficient diet is to not eat protein, and this would not be alleviated by any inorganic source of nitrogen, even if we could consume enough of such a N source.
The following is multiple choice question (with options) to answer.
A deer eats lots of grass, but the deer is unable to create more food for itself, because in the food chain, the deer is unable to be | [
"a producer",
"a consumer",
"a manager",
"a creator"
] | A | producer is a kind of role in the food chain process |
OpenBookQA | OpenBookQA-698 | mechanical-engineering, car
Stablity/Aerodynamics -- This is less of an engineering perspective than a practical one, but for a "regular" car there will be a certain point that the suspension and other components are not sufficient to keep the car driving straight down the road in a safe fashion. Anecdotal evidence to support this point comes in the form of a story about an old '70s full-size American car that, when taken up to triple-digit speeds, did not have the aerodynamic capabilities to keep the front wheels on the ground. In short, the lift from the air moving under the car lifted the front wheels off the ground into a terrifying high-speed "wheelie". Though this process did not technically cause the car to slow down, it certainly made it difficult to control at that speed.
The following is multiple choice question (with options) to answer.
which of these would most likely cause a car to lose control? | [
"a nice dry asphalt highway",
"a highway after cloud precipitation",
"a dry cobble stone road",
"all of these"
] | B | as moisture of an object decreases , the friction of that object against another object will increase |
OpenBookQA | OpenBookQA-699 | newtonian-mechanics, forces, energy, work
... the potential energy should increase by $mgh$ joules as the kinetic energy is kept constant, meaning that there has to be some total work done on the object.
To specifically address this point, there is nothing that says a change in potential energy means the net work done on an object is not $0$. This example is clearly a counterpoint to this claim.
The following is multiple choice question (with options) to answer.
Potential energy changes to kinetic energy when using a | [
"computer",
"light bulb",
"television",
"bicycle"
] | D | potential energy changes to kinetic energy through motion |
OpenBookQA | OpenBookQA-700 | python, beginner, game, functional-programming, adventure-game
winter = '\n' + '''29 January 2029. It is five weeks into winter and the season shows no mercy. A drought happened for a majority of the last fall and it devastated
the food supply. As your community dives deeper into the winter, you realize that your supply will run out if consumption is not altered. You could do one of two options: reduce
consumption among civilians, or ignore the risk and take a chance([ALTER SUPPLY]X} {B[IGNORE RISK]).''' + '\n> '
alter_supply = '\n' + '''Your government is now seen as selfish. You took the risk to protect the important people and "do your best with the rest". You have suffered heavy
civilian losses but your army and government losses have been few. As a result, there is division and danger in the streets. Riots breaking out, murders, arson, all happening in
your community.''' + civil_great_decrease
ignore_risk = '\n' + '''Your community did better than expected during the period. That is until you ran out of food in early March. Now you rely solely on scavenging,
risking getting devoured by zombies in order to go another day. Half your community is either dead or lost with great amount of casualties from civilians and
non-civilians.''' + army_great_decrease
The following is multiple choice question (with options) to answer.
Many families survive the winter thanks to | [
"tv",
"AC unit",
"furnace",
"fridge"
] | C | natural gas is a source of heat by burning |
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