source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-4601 | evolution, evolutionary-game-theory, altruism
has little explanation. One possible explanation is that the trait itself may correlate well with genetics. One great answer there is that often the cost of altruism is small anyway. It can explain why people vote. Here the expense is small anyway.
Still there seems to be some factors that are even bigger.
Let's take a look at people that die for their ideology. Christian martyrs, Muslim suicide bombers, or Communist guerilla fighters. They seem to get so little and well, die.
And that's pretty common. It seems pretty easy for a leader or pedagogue to rouse men to be soldiers. Of course, becoming a soldier is a pretty shitty job, yet most men don't mind.
These people make a huge sacrifice for the sake of their country, ideology, or people that are not even genetically related to them.
Why? Your question is quite broad and asks for explanations for various behaviours which can lead to self-sacrifice.
Religious reasons: The genetic influence here may be a predisposition to let others influence you. This is what gives rise to culture in the first place, in other words: the predisposition to at some point maybe sacrifice yourself because you are taught to do so can only die out if the basic behaviour which gives rise to culture dies out. Cultures which lead their members to die may decimate their own numbers, but they will not wipe out culture itself because in the bigger scale, those with culture do better than those without. (Plus, those who sacrifice themselves may have children as well, so any genetic influence on their behaviour can be carried on.) This also goes far into the field of memetic evolution, which is disputed but may be interesting to read about.
Political reasons: As in, dying for one's nation or country rather than because of teachings. This probably has a defensive behaviour towards one's own group as the genetic influence. Also, reputation plays a big role: see shigeta's excellent answer.
You also mention willingness to subordinate oneself which is a very common pattern not only in humans. Richard Dawkins touches on this in The Selfish Gene, but there are probably papers more focussed on this particular topic out there as well.
The following is multiple choice question (with options) to answer.
Why would philanthropists donate special straws to help poor countries? | [
"they pollute water",
"they need straws",
"they treat water",
"they poison water"
] | C | treating water is used to remove harmful substances before drinking |
OpenBookQA | OpenBookQA-4602 | POLLUTION - A contaminated lake is treated with a bactericide
POLLUTION - A contaminated lake is treated with a bactericide. The rate of increase in harmful bacteria t days after the treatment is given by Where N (t) is the number of bacteria per milliliter of water. Find the minimum value of dN/dt. If the initial count was 5,000 bacteria per milliliter, find N (t). Find the bacteria count after 10 days. Use your calculator to minimize the given function. The minimum value is – 1000. b. Integrate dN/dt ’ to find N. Let u = 1 + t 2 then du = 2t dt and the integral becomes CONTINUED
Find C. The initial count was 5000 when t = 0.
c. Find N (10). 10 days after treatment the bacteria count will be 385 bacteria per milliliter of water.
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The following is multiple choice question (with options) to answer.
treating water is used to remove harmful substances before what? | [
"emptying",
"guzzling",
"evaporating",
"disposing"
] | B | treating water is used to remove harmful substances before drinking |
OpenBookQA | OpenBookQA-4603 | intelligence
There might of course also be recessive genes on the X-chromosome causing males, who has only one X-chromosome, to be smarter but genes that are not causing disease might not be so interesting to investigate from a medical point of view.
According to wikipedia there are 499 x-linked genes and the total number of "vaguely defined traits" are 983.
I would say that yes, as a man you inherit more genes from your mother than from you father affecting your intelligence due to the fact that some genes on your x-chromosome affect your intelligence. Whatever the 499 x-linked genes do, you could say that traits affected by those genes to a greater extent are determined by your mothers genes than by your fathers, if you are a male.
Technically you would of course also have to take the genes on the y-chromosome, which are much fewer, into account.
The following is multiple choice question (with options) to answer.
An inherited characteristic from my dad is | [
"nasal structure",
"a building",
"the bike",
"the cat"
] | A | the shape of body parts is an inherited characteristic |
OpenBookQA | OpenBookQA-4604 | genetics
Title: What distinguishes Mendelian Inheritance from Non-Mendelian Inheritance? I'm having some trouble determining what exactly is the difference between Mendelian inheritance and non-Mendelian inheritance. For instance, I understand that chromosomal abnormalities such as Down's Syndrome fall under non-Mendelian inheritance because they concern chromosomes, not single genes. And I also understand that Mendelian inheritance concerns single genes, as in Sickle-cell anemia (which is an autosomal recessive disorder).
What confuses me is the fact that our textbook discusses dihybrid and trihybrid (concerning 2 genes and 3 genes, respectively) crosses under the Mendelian inheritance chapter, when to me it seems like these crosses are non-Mendelian because they deal with multiple genes. However, Gregor Mendel did in fact use the dihybrid cross to deduce the law of independent assortment, so I'm completely confused. Could someone please clarify this for me? I'm afraid that I'm maybe misinterpreting something. You can discuss multiple genes within the framework of Mendelian inheritance; what you're probably thinking of, though, is the fact that Mendelian inheritance doesn't recognize the idea of multiple genes that contribute to a single trait.
For example, if there is a gene that controls petal color (blue vs. white, with blue = dominant) and a gene that controls height (short vs. tall, with tall = dominant), then Mendelian inheritance predicts that two short plants with white flowers will only produce short plants with white flowers.
But if there are multiple genes that interact to determine height in a complex way, that's outside the scope of Mendelian inheritance.
The following is multiple choice question (with options) to answer.
Which of these are inherited instead of acquired? | [
"wealth",
"height",
"prison time served",
"wisdom"
] | B | the shape of body parts is an inherited characteristic |
OpenBookQA | OpenBookQA-4605 | immunology, virology, pathology, epidemiology, coronavirus
Evolution of virulence in ways predicted by the theory has been observed in the real world in such diseases as myxomatosis (a viral disease of rabbits). The theory has also been suggested to apply in HIV and syphilis.
The actual forecast can depend on many details of the biology and epidemiology of a particular organism. If COVID-19 happened to have a higher-than-optimal virulence in humans at the time of emergence, we could expect its virulence to decline over time. It could also decline if epidemic control was applied in such as way as to differentially affect more-virulent strains; this has been suggested by Tang et al. on the basis of the pattern of mutations in different strains, although their logic has also been criticized on Twitter by an expert in genetic epidemiology, and now by a more official rebuttal by McLean et al. (with some back-and-forth discussion between the authors and critics).
This explanation doesn't include the possibility of host evolution, which is theoretically important but not really relevant to COVID-19 — it would only happen over many generations, and only if the epidemic was so severe that it was a significant overall cause of death or failure to reproduce ...
The following is multiple choice question (with options) to answer.
Children are more likely to get smallpox if | [
"their parents base their medical decisions on advice from has-been adult entertainers",
"they undergo vaccination at an early age",
"they're vaccinated when they're young",
"their parents understand basic science"
] | A | vaccines can help prevent illness |
OpenBookQA | OpenBookQA-4606 | time, speed
Title: Can people traveling at difforent speeds gain information at a different rate? I heard that the faster you go, the slower time around you goes. For example, if you where in a rocket going very fast and you started a timer for 1 minute at the same time someone walking down the street started a timer for 1 minute, the person on the street's timer would go off just before yours. I also know that people going at very fast speeds can still get information (for this example lets say that it is from the internet).
So lets imagine that the person on earth starts streaming a TV show to the person in the rocket. Can the person in the rocket watch the TV show faster than the person on Earth? This would not make sense to me, given that they both experience time at the same speed.
This would not make sense to me, given that they both experience time at the same speed.
See this answer of mine for background. Although I'm not a psychologist, I think it's reasonable to surmize that the experience of time is defined by how quickly one's own bodily processes run forward relative to the rate of other physical processes in one's nearby, comoving neighborhood. This explains why the rate of one's own time progression is never perceived to be anything other than "one time unit per one time unit".
But this does not stop signals arising from sources elsewhere that one receives from progressing at different rates if the relative motion between source and receiver change.
And, your spacefarer will indeed see the television transmission progressing more swiftly, or more slowly, depending on whether their motion is towards or away from the signal source.
There are two simple ways to see this.
The following is multiple choice question (with options) to answer.
In the 60's people watched on TV while for the first time people walked on | [
"a high rooftop in a major city",
"a satellite without much air in our solar system",
"the edge of a cliff in the mountains",
"a beach in Brazil"
] | B | the solar system contains the moon |
OpenBookQA | OpenBookQA-4607 | electricity, electric-circuits, electric-current
I was wearing flip flops from the time I stripped off my neoprene wet suit at the car until the time I started getting shocked (my wife was wearing Birkenstocks).
I had been snorkeling for about an hour in the Pacific Ocean wearing a full body wet-suit, booties, and gloves (no hood).
I had been camping the night before and consumed quite a bit of Gatorade.
My wife had only been wearing a spring suit and gloves, no booties.
There was another receipt that had been left in the machine (maybe someone else had been shocked as well and decided it wasn't worth the risk of going after it?)
I can't think of anything else relevant. Any insights into what was going on here would be welcome. I tried calling the maintainers of the machine but couldn't get through (this was before I found out that I seemed to be the only one affected).
Thanks!
She tried touching the machine in various places, again nothing. I inadvertently touched her hand while she was touching the machine and then suddenly she felt it too.
From this it is evident you were a good conductor to the ground.
You later say :
We came back out 15 minutes later after drinking our hot chocolate and tried to reproduce the phenomenon with no luck.
So no charge was passing through you any longer?
15 minutes is too little a time to change your conductivity. It could be a combination of an intermittent fault in the circuit and your conductivity at that time. You should alert their maintenance to be on the safe side.
The following is multiple choice question (with options) to answer.
A person in a suit near a sunken ship is sprayed in the face with a dark substance by | [
"a cephalopod",
"a bear",
"a hose",
"a pencil"
] | A | ink is used for hiding from predators by octopuses |
OpenBookQA | OpenBookQA-4608 | entomology
Title: What is the name of this tiny creature? It looks like a tiny piece of moving cotton? By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name? From your image, it looks like it might be a woolly aphid. I just did a bit of cursory research, and it looks like they're often described as floating pieces of fluff, that seem to wander instead of directly heading somewhere. The fluff on their back is actually wax produced as a defense mechanism from predators and the like. I hope this is what you were looking for!
The following is multiple choice question (with options) to answer.
Octopuses excrete an ink as defense when | [
"They're in danger",
"they are flying",
"cooking",
"never"
] | A | ink is used for hiding from predators by octopuses |
OpenBookQA | OpenBookQA-4609 | newtonian-mechanics, newtonian-gravity
Title: On a low gravity planet, as a pedestrian, would having more mass be an advantage? Say this planet (or body since it would be too small to be classified as a planet) has a gravity of 0.1g or less. Perhaps any small force (bumping into another human) could cause you to fly off the ground, making you float far distances. This would be a huge inconvenience.
Would weighing yourself down via a suit, maybe enough to simulate 1g be an advantage? Could there even be a celestial body where gravity is low enough, that gently pushing someone would be an issue? If you are heavier than the other humans, then indeed the additional gravitational force would be an advantage. However, if all the humans do the same thing, bumping into them will generate a proportionally higher force, and it won't help you. Except, perhaps, that the heavier people will tend to move more slowly.
If you could weigh down just the shoes (like the old diving suits) you might improve the situation a little: the force of the "bump" would be with the lighter part of you (less impact), while the force of gravity would still be increased.
The following is multiple choice question (with options) to answer.
Gravity lessens as you go | [
"alongside a friendly black hole",
"away from a planet",
"closer to a planet",
"closer to the sun"
] | B | as distance from an object decreases , the the pull of gravity on that object increases |
OpenBookQA | OpenBookQA-4610 | ecology
Title: Do invasive species cause long-term damage to ecosystems they invade? Growing up in the U.S., I was warned at various times of the dire consequences of a variety of introduced pests (usually insects).
Japanese beetles, gypsy moths, and most recently the brown marmorated stink bug are all introduced pests that, at various times, were described as serious threats to our ecology.
These threats aren't confined to arthropods, either. The giant African land snail is causing a stir in Florida (indeed, Florida seems to suffer from an excessive variety of introduced species.
"Lack of native predators" is frequently cited as the primary reason many invasive species are considered such a risk to the ecology.
I understand that these introduced species can place tremendous pressure on native species that fill similar ecological niches, and may even push these species out of the region due to competition for food and habitat. However, do the overall ecologies that these species are introduced to adjust over long periods of time?
The numbers of Japanese beetles and gypsy moths don't seem anywhere as high as when I was a child. Has the ecosystem adjusted, or has the overpopulation self-corrected as the species ran low on food through over-consumption? Or are the populations still just as problematic now as they were 30 years ago, and I just am not seeing the bigger picture?
What is the long-term impact that we've seen from invasive, introduced species? Is there a significant difference on the long-term impact between introduced flora, arthropods, or mammals? The answer really depends on how you think of invasive. One extreme answer is to say that all things are relative, and that the concepts of local and invasive are all relative. This matters to a certain extent because ecologists draw a fuzzy line between invasive and naturalized. You could start with some basic species that we all think of as either good, local, or neutral. Take the earthworm. Most people think of it as a common native species, but the earthworm is actually an invasive species that has radically changed much of North America that came over with the Europeans. Similarly, brown trout are also invasive, coming to the US in the 1800's.
The following is multiple choice question (with options) to answer.
Humans moving into an environment usually causes native species to lose their what? | [
"beauty",
"housing situation",
"minds",
"young"
] | B | humans moving into an environment usually causes native species to lose their habitats |
OpenBookQA | OpenBookQA-4611 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
A creature lives in a portion of forested area, and only is able to live in that area. A group of bipeds begin to make their own homes in that space. The creature which originally lived there is most likely to | [
"share their space",
"sell that space",
"lose their space",
"fight for space"
] | C | humans moving into an environment usually causes native species to lose their habitats |
OpenBookQA | OpenBookQA-4612 | visible-light, everyday-life, diffraction, light-emitting-diodes
It's not that good visible, but the pixels are rectangular shaped (in vertical position). They are much smaller than the pixels on my big TV-screen, which I almost can see with the naked eye (once you know the shape after taking the close-up picture, which can't be said of the pixels of my laptop's screen). The effect isn't visible on my (power off) laptop screen, maybe because of the smallness of the pixels. The effect is (as I said ) color-dependent (with a red beam of light only a red X-form, periodically bright and dark is seen) and orientation independent (no matter how I point the light beam the same X appears over and over again). Nevertheless, I don't know if the pixels on both screens are the same (though it appears so). It looks like a diffraction pattern from the pixels of the screen. In a different SE question, the pattern was four horizontal and vertical "rays" consisting of finely spaced peaks, rather than the wide spacing here and the angles that differ from 90 degrees.
If you measure the apparent angle between the first diffraction peaks (the ones at the edge of the halo) and the central spot, you can relate that to the wavelength (say, 600 nm) and the dot pitch of the tv screen. The ratio of distances screen-eye versus screen-candle also matters; the analysis is easier if this ratio is much smaller than one.
Regarding the angle between the rays: I suspect that your screen does not have rectangular pixels, but pixels arranged in some kind of staggered arrangement. However, I can't guess the exact pixel arrangement from the diffraction pattern. It could also be that you took the photo from an angle. Maybe you could post a picture of the TV pixels in close-up (when the TV is on) and a sketch of the relative locations of camera, candle, screen, and apparent diffraction spots.
Update
The following is multiple choice question (with options) to answer.
Jim was looking straight at his neighbor's bright Christmas display but it looked very dim to him. That's because | [
"Jim was wide awake",
"Jim was a mile away",
"Jim was a few feet away",
"The lights were of different colors"
] | B | as distance from a source of light increases , that source of light will appear dimmer |
OpenBookQA | OpenBookQA-4613 | 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.
Which is true about flashlights? | [
"they are pure silicon",
"they fade out over time and distance",
"they last literally forever",
"they work better over distance"
] | B | as distance from a source of light increases , that source of light will appear dimmer |
OpenBookQA | OpenBookQA-4614 | ocean, ocean-currents, tides
Direct disruption of seabed habitats by physical interference, e.g. from moorings
Disruption of ecological niches: Some organisms have evolved to survive in areas where others cannot - e.g. high current speed environments. Changes in seabed conditions, e.g. from greater or lesser current speeds, may cause them to be out-competed by other species that can then settle there.
Similarly, changes to sediment distribution represent changes to seabed habitats.
Alteration of flow patterns could have implications for species with a dispersive juvenile stage (e.g. larvae that rely on currents to spread) or those that rely on current flow for nutrient or waste transport.
The following is multiple choice question (with options) to answer.
What changes an ecosystem? | [
"sunbathing",
"rock climbing",
"extracting coal",
"swimming"
] | C | mining changes an ecosystem |
OpenBookQA | OpenBookQA-4615 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Which of these industries is most likely to effect an ecosystem? | [
"food",
"coal",
"solar",
"retail"
] | B | mining changes an ecosystem |
OpenBookQA | OpenBookQA-4616 | Say colour 1 is used twice.
There are (5×4) /2 ways of painting 2 out of the 5 buildings.
Now there are 4 colors, so the above is true for each of the 4 colors.
We have 4 × [(5×4)/2] ways of painting 2 out of the the 5 buildings with the same color.
3 remaining buildings still need to be painted with the remaining 3 different colors.
For each of the ways where 2 equal colors have been used on 2 out of 5 buildings we can paint the remaining 3 buildings in 3×2×1 ways
Altogether: 4 × [(5×4)/2] × (3×2×1) = 240.
The following is multiple choice question (with options) to answer.
What do you have the most time to paint a nature scene outside? | [
"Spring",
"Summer",
"Fall",
"Winter"
] | B | the amount of daylight is greatest in the summer |
OpenBookQA | OpenBookQA-4617 | magnetic-fields, earth
Title: Would a compass on its side point at the ground? From a point just north of the equator, A straight line to the Magnetic North would be through the earth. If a compass was turned on it's side, would the north pointing arrow point toward the ground along that straight line? A compass is usually used to find the direction of the horizontal magnetic field of Earth at that point. The needle of a compass is very light and thus its efficiency decreases when the compass is not in the horizontal plane at that point (due to gravity).Therefore, where the compass would point will become unpredictable. But, yes, in ideal conditions, the compass would point along the straight line joining that point to the north pole.
The following is multiple choice question (with options) to answer.
What force causes a compass in Illinois to point towards Wisconsin? | [
"natural magnetism",
"wind direction",
"weight",
"gravity"
] | A | natural magnetism is used for pointing north by a compass |
OpenBookQA | OpenBookQA-4618 | magnetic-fields, earth
Title: Would a compass on its side point at the ground? From a point just north of the equator, A straight line to the Magnetic North would be through the earth. If a compass was turned on it's side, would the north pointing arrow point toward the ground along that straight line? A compass is usually used to find the direction of the horizontal magnetic field of Earth at that point. The needle of a compass is very light and thus its efficiency decreases when the compass is not in the horizontal plane at that point (due to gravity).Therefore, where the compass would point will become unpredictable. But, yes, in ideal conditions, the compass would point along the straight line joining that point to the north pole.
The following is multiple choice question (with options) to answer.
Who would likely need a compass? | [
"a fish",
"a taxi driver",
"a bobcat",
"a seaman"
] | D | natural magnetism is used for pointing north by a compass |
OpenBookQA | OpenBookQA-4619 | zoology, entomology
Title: Help identifying an insect I live in Milan, Italy in the city center. I live in this house since 5 years and I keep finding the insect pictured below.
I see it throughout the seasons (temperatures here range from -1°C to +35°C in average).
I find it mostly in my bathroom which is not well ventilated and it is the warmest room in the house (about 23°C in winter even with the radiators off and up to 35°C in summer during very hot days if I don't use air conditioning).
The size is about 7mm in length and 1mm in width (including only the main body, i.e., excluding legs and antennae).
I find it mostly during the night but maybe just because I use brighter lights and I can see it more clearly on my white walls.
What is its name so I can research more about it (i.e., does it pose any risk to my health or to my belongings in the house?)? Looks like a species of silverfish.
https://en.wikipedia.org/wiki/Zygentoma
They eat paper, cloth and stored foods like cereal, even organic wall paste, so yes they can damage your stuff, but outside allergies they are harmless to a person.
The following is multiple choice question (with options) to answer.
Warm weather organisms live in what kind of climates? | [
"icey",
"summerlike",
"frosty",
"frigid"
] | B | warm-weather organisms live in warm climates |
OpenBookQA | OpenBookQA-4620 | fluid-dynamics, kinematics, momentum
Title: Could a fish in a sealed ball, move the ball? If you had a glass ball filled with water, completely sealed and containing a fish, could the fish move the ball? Yes, with gravity and a generous definition of "moving".. it would be the same principle as the toys where you can control a sphere using a radio control (or using your iphone). The fish swims along the edge and gravity pulls it back down, which starts a rotation of the water and by friction to the sphere starts the rolling motion of the sphere on the ground or other surface. Obviously the water/sphere friction will probably be miniscule, but at least it is possible in theory :)
A follow-up question would of course be if it's possible to move a hermetically sealed sphere freefloating in vacuum and without gravity or any other appreciable fields intersecting it. If you solve this, I'm pretty sure NASA will want to talk to you (or the fish)!
The following is multiple choice question (with options) to answer.
A squid can swim faster by using the what from its body thrusts? | [
"pullinh",
"power and energy",
"growing",
"science"
] | B | a squid produces thrust by pushing water out of its body |
OpenBookQA | OpenBookQA-4621 | entomology, ecology, biological-control
Habitat modification: regularly removing
plant growth within the lake and trimming vegetation overhanging the edges will limit the ability of mosquito larvae to escape predators and may have some effect. However, the recent management you describe has
probably gone some way towards this (did you
notice whether the mosquito problem got any better after the plants
were removed?)
Biological control: introduce predators or parasites into the environment. Plenty of species eat adult mosquitoes but there aren't really any that primarily feed on them (unless they're the only food source available) and many adult mosquitoes will have laid eggs already - the most effective strategy will be to target the immature population. Larvivorous fish have been shown to be effective in many parts of the world, for example fish in the genus Gambusia ('mosquito fish'). I don't know of any that have been shown to be effective and can thrive as far north as Scandinavia, but if you stock the lake with fish (combined with managing vegetation as above) I'd be surprised if you don't see some improvement.
Biological control, part 2: Use Bti (Bacillus thuringiensis var. israelensis). This is a bacterium that produces toxins which are highly specific to dipterans and don't really affect anything else. You can buy the bacterium in various formulations including sprays, tablets etc. I'm mainly familar with its use for controlling container-breeding mosquitoes, but this paper describes its use in large lakes so should give you some idea of dose required, optimal application method and time to reapplication.
Without knowing more about your budget, available time/manpower etc I can't really help you choose between these but I suspect #3 is your best bet.
The following is multiple choice question (with options) to answer.
If a load of deer are moved to a small park, and they are repeatedly sprayed with pesticides, the | [
"deer thrive in that environment",
"deer are healthy and happy",
"deer are given happy lives",
"park will eventually be deerless"
] | D | harming an animal species causes that animal 's population to decrease |
OpenBookQA | OpenBookQA-4622 | evolution, species
Title: Parents that eat their own children I am told that there are some species, like fish or rabbits, that if let, will eat their own children. If this is true, how does a species like this exist? Shouldn't the fact that they kill their own lineage make them nonviable? Yes, it is true.
Prairie dogs
Prairie dogs for example are known for frequent infanticides.
Many other species kill their babies too
But of course, such behaviour also exists in other lineages such as grey langurs, gerbilles, lions, giant water bugs and Bottlenose dolphins (just to cite a few examples).
How does that evolve
It will be impossible to provide a complete universal explanation to this behaviour because the evolutionary processes causing this behaviour varies from lineage to lineage. For examples, in lions, only males kill young of the females that are still nursing and they do so when taking over a new harem only. In prairie dogs, mothers cause infanticide preferentially on others' babies but also on their own babies.
Going into the details of how such behaviour evolves in every specific lineage would probably require writing an intro on kin selection and other fields of evolutionary biology which is way too much for a single post. You may want to have a look at the wikipedia article infanticide for a start.
Shouldn't the fact that they kill their own lineage make them nonviable?
Of course, they don't kill all the babies. Only a fraction of them!
The following is multiple choice question (with options) to answer.
harming an animal species causes that animal 's population to do what? | [
"explode",
"rise",
"plummet",
"burst"
] | C | harming an animal species causes that animal 's population to decrease |
OpenBookQA | OpenBookQA-4623 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
A creature is able to receive nutriment throughout their limbs due to | [
"arteries",
"jeans",
"oranges",
"arms"
] | A | veins transport nutrients throughout the body |
OpenBookQA | OpenBookQA-4624 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
A rabbit receives his essential elements from his | [
"boat",
"stock brokers",
"subway",
"circulation system"
] | D | veins transport nutrients throughout the body |
OpenBookQA | OpenBookQA-4625 | electric-circuits, electric-current, electrical-resistance, batteries, short-circuits
Title: The importance and the role of a switch in an electrical circuit There is this simple test:
Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed:
a] The brightness of $A$ and $B$ remains the same, while $C$ goes out.
b] The brightness of $A$ and $B$ remains the same, while that of $C$ is halved.
c] The brightness of $A$ and $B$ decreases while $C$ goes off.
d] The brightness of $A$ and $B$ increases while $C$ goes off.
For my opinion the answer to this question is D because the switch (which has a resistance of $0\, \Omega$ has a node connected before the third bulb C) that "interrupts" the circuit. But, going into detail, according to Kirchhoff's first law the current should also go on the third bulb as in the first red node it divides into two currents $I_1$ and $I_2$. The current $I_1$ goes for example in the key $S$ and $I_2$ in the third bulb. The key and the third bulb have the same potential difference. I believe that the current $I_2$ passes through the third bulb but the current passing through it is so small that it does not turn on.
I made a point. When an individual is operated on at the heart and puts a by-pass (a bridge), blood will flow on the tube that detects the by-pass and the occluded artery (the third bulb) where blood will flow slowly, over time it will atrophy.
If the circuit were like the one drawn in the picture I would answer the b).
My question is: I have not very clear the rule of a switch in a eletric-circuit.
In fact, I find it difficult to give an answer to the following image.
The following is multiple choice question (with options) to answer.
This likely relies on a circuit being closed | [
"your iPhone charger",
"your hair brush",
"your hat",
"your shoes"
] | A | when a switch in a simple series circuit is closed , electricity will flow through the circuit |
OpenBookQA | OpenBookQA-4626 | identification, minerals
Title: How can chemists distinguish pure chemical element specimens that look almost "the same" as well as what deposit is what in a multimineral mined rock? As a non chemist I am most often charmed when visiting Wikipedia articles of chemical elements and see images of very pure specimens of element after element, proton by proton, and often also metal cube specimen made from smithing similar pure deposits.
The wiki article Periodic table allows me to do so easily; here are some elements I found looking almost the same and don't think I personally could distinguish between them without some instrument:
molybdenum and manganase
titanium and chromium
rutenium and cadmium
sodium and aluminium
silicone and germanium
The following is multiple choice question (with options) to answer.
to determine how firm a certain mineral may be a person can: | [
"measure the weight of it",
"attempt to leave a mark on it",
"crush it to see the inside",
"see if it can bounce"
] | B | quartz scratches glass easily |
OpenBookQA | OpenBookQA-4627 | optics, electromagnetic-radiation, visible-light, reflection, geometric-optics
Title: We know that a window can actually reflect light. But if the window has some dirt sticking to it, the image we see sometimes get magnified. Why? Well, I was traveling in a bus yesterday and saw this occur. The board that separates the passengers from the driver's had something written on it and I saw that the window that was a few meters away from the board reflected all of the things written.. But the window had some dirt on the part where I saw the image of the writings... And, they appeared to be enlarged just at the point where dirt was present. The open spaces between dirt particles each acts like a "pinhole camera" to magnify the image behind the dirty glass pane. The magnification is slight but noticeable. Try this experiment: make a small triangular hole shape by putting three fingertips together so as to leave a gap at their intersection. by pressing your fingertips together, you can make the size of the hole shrink; by relaxing them, you can make the hole larger.
That hole will act as a pinhole camera. now look through the hole at your computer screen from about 24 inches away and vary the hole size. you will find a certain diameter at which the image you see through the hole will get sharper and the text on the screen will become easier to read.
The following is multiple choice question (with options) to answer.
You can etch the surface of a windshield with | [
"a sponge",
"feathers",
"soft cloth",
"jasper"
] | D | quartz scratches glass easily |
OpenBookQA | OpenBookQA-4628 | newtonian-mechanics, estimation
Would the rock have created a seismic event of its own (if so, how large)?
Would the rock have created a crater? The energy of the rock at the time of hitting the earth is mgh.
No rock we know of is going to be able to survive this collision with out breaking into pieces.
Non the less it will be a big impact and depending on the geology of the location it hits a variety of reactions scenarios can happen.
If the soil is aggregate of silt and sand and gravel, it would part into several shear rupture sections which look like slices of shell pattern surfaces starting from the bottom surface of the rock and turning up exiting the earth surface a few hundred yards outside of the impact zone and probably even eject some material out like a bomb crater. This scenario will have shakes that could be recorded miles away.
The calculation of how much of the momentum of rock will be shared with the shear material and accelerating them will be involved but not impossible.
If the geology of the impact area is of very low bearing like mostly silt and loose clays, the rock my lose most of its kinetic energy by just sinking into the dirt mostly with a giant humph with a cloud of dust rising.
If the geology is hard or rocky with the 'optimal' amount of mass and resilience it could create a substantial earthquake by resonating with the impact.
The following is multiple choice question (with options) to answer.
Rocks are most likely to kill you while | [
"hiking a mountain",
"in a pool",
"at a concert",
"in a cornfield"
] | A | landslides often occur on mountains |
OpenBookQA | OpenBookQA-4629 | visible-light, atmospheric-science, sun
Title: Why is there less UV light on earth in winter? So I have often read that, at least in e.g. northern Europe, in the colder seasons, there is not enough UV (-B) light arriving from the sun, so many people have not enough vitamin-D from that.
At first I thought it was simply due to the sun "shining" for only a much shorter period of time in winter compared to summer and hence less possible exposure (not to mention that most of the skin area is covered then).
But I just had a thought coming to my mind, thinking about that in the mornings and evenings, we mostly see red light here, the higher end of the visible spectrum not getting through.
I am not familiar with the physics behind that phenomenon, but thought that the higher-end of the spectrum like the invisible UV light may not be getting through here for even longer parts of the day towards and away from high noon, and that in winter, the part of the day where UV gets through is maybe very narrow and that's why it's said not to be enough.
Is that correct? And how exactly does this work physically? The reddening of the sun has to do with Rayleigh scattering as the sun passes through more atmosphere. (see picture). This is in a sense, related to less energy but not the primary cause.
The reason we get less solar energy per square meter is that the angle of the sun in the sky affects how spread out the light is. (see updated picture). Ignoring atmospheric effects, it's the sin of the angle times peak energy. 90 degrees or directly overhead, figuring peak solar energy is 1,369 Watts per square meter (that also varies with distance), but the energy from the sun is mostly governed by the sin of the angle.
45 degrees: 1,369 * sin(45) W/m^2 or 71% of overhead or Zenith. 20 degrees above horizon, 1,369 * sin (20), just 34% of peak solar energy. Winter corresponds with the sun being lower in the sky, sunlight is more spread out. There is measurably less energy hitting the same area when the sun is low in the sky.
Passing through more atmosphere amplifies that somewhat, but the angle of the sun is the primary cause.
The following is multiple choice question (with options) to answer.
This would be associated with a lack of sunlight: | [
"a wide sandy desert",
"carbonic acid in groundwater",
"a tropical beach scene",
"a rice plantation in the North"
] | B | a cavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone |
OpenBookQA | OpenBookQA-4630 | # Word problem help
#### Stephen
could you please tell me how I set this up to solve? thanks
a veterinarian has two solutions that contain different concentrations of a certain medicine. One is 15% concentration and the other is 5 % concentration. How many cubic centimeters of each should the veterinarian mix to get 20 cc of a 6 % solution?
#### Grandad
MHF Hall of Honor
Hello Stephen
Welcome to Math Help Forum!
could you please tell me how I set this up to solve? thanks
a veterinarian has two solutions that contain different concentrations of a certain medicine. One is 15% concentration and the other is 5 % concentration. How many cubic centimeters of each should the veterinarian mix to get 20 cc of a 6 % solution?
Suppose he uses $$\displaystyle \displaystyle x$$ cc of the first solution, and $$\displaystyle \displaystyle y$$ cc of the second. Then we can set up two simultaneous equations as follows:
The total volume must be 20 cc. Therefore
$$\displaystyle \displaystyle x+y = ...$$ ?
This is equation (1).
The quantity of the medicine in $$\displaystyle \displaystyle x$$ cc of the first solution is $$\displaystyle \displaystyle \frac{15x}{100}$$.
The quantity of the medicine in $$\displaystyle \displaystyle y$$ cc of the second solution is $$\displaystyle \displaystyle \frac{5y}{100}$$.
The total quantity of medicine in the mixture is therefore ... ?
This must be 6% of the total volume, $$\displaystyle \displaystyle 20$$ cc, which is $$\displaystyle \displaystyle \frac{6\times 20}{100} = ...$$ ?
The second equation is therefore
$$\displaystyle \displaystyle \frac{15x}{100}+\frac{5y}{100}=...$$ ?
This is equation (2).
Can you complete what I have started, and then solve the simultaneous equations to find $$\displaystyle \displaystyle x$$ and $$\displaystyle \displaystyle y$$?
Grandad
#### Soroban
The following is multiple choice question (with options) to answer.
Kool-aid is a mix of what items as a solution? | [
"water fluid within a sugar casing",
"soda pop within a can",
"sucrose crystals and flavors dissolved in liquid base of water",
"sugar candy from store"
] | C | a cavern is formed by carbonic acid in groundwater seeping through rock and dissolving limestone |
OpenBookQA | OpenBookQA-4631 | the-sun, red-giant
However, even if the Earth escapes immediate engulfment, the Sun would be several thousand times more luminous than it is today, so the temperatures at the surface of the Earth could reach $>1000$ Celsius even if it stays an astronomical unit away from the Sun's surface.
A further issue is the effects of tidal dissipation. The Earth will be dragged back by tidal bulges induced in the Sun's extended envelope. The rate at which angular momentum is lost is however exquisitely sensitive to the exact radius of the Sun and the radius of the Earth's orbit, to the extent that their orders of magnitude uncertainty in whether the Earth will be dragged into the Sun's envelope even before it reaches the tip of the RGB (this is what Schroder & Smith 2008 claim) or whether the loss rates will be too low to have much effect. It all depends on how much mass loss there is (Schroder & Smith use a slightly lower estimate than above) and therefore what radius the Earth reaches and what the final radius of the Sun becomes.
At the moment I would say there is sufficient uncertainty that the fate of the Earth is undecided, but it will unarguably be uninhabitable.
The following is multiple choice question (with options) to answer.
If a large boulder is kept in direct sunlight it can | [
"become powerful",
"grow larger",
"gain chill",
"lose portions"
] | D | being exposed to heat can cause erosion of rocks |
OpenBookQA | OpenBookQA-4632 | thermodynamics
In this scheme, at steady state, the only mechanism for loss is where the stone is in contact with air or just below the surface local heating leads to a locally high temparature stone / water, and this can then lose heat to the air. You can make this small (1) by ensuring that most of the stone is steeped deeply in the water - so you want a long thin one and (2) making sure that the conductance (rate of heat transfer per unit area across the stone-air interface) is small compared with the stone-water conductance. If these conditions are met, then at steady state the stone will be almost at a uniform temperature and hotter than the surrounding water.
A second scheme is this: you transfer heat in cycles by heating the stone, then steeping in water to let it cool there, then taking the stone out and repeating the cycle. Here is where the problem is ill posed: what's best? Do you want to transfer heat as quickly as can be? Do you want the water's temperature to rise the fastest? If so, then three factors weigh on your scheme: (1) the stone's heat capacity $S$ (mass times specific heat capacity), (2) conductance across the stone-air interface $C_{s,\,a}$ and (3) conductance across the stone-water interface $C_{s,\,w}$. Now let the time throughout which you heat the stone be $t_H$ and the time throughout which the stone is steeped in water be $t_S$. Let the incident light's intensity (irradiance if you're an illumination specialist) be $I$ and the stone's temperature at the beginning of this cycle be $T_b$.
As the stone is heated, its temperature $T$ follows
$${\rm d}_t T = \frac{I}{S}-\sigma \,T^4 - C_{s,\,a} (T-T_a)$$
The following is multiple choice question (with options) to answer.
If a rock has been exposed to prolonged heat, what might the effect be? | [
"Shrinking",
"Breaking",
"Erosion",
"Melting"
] | C | being exposed to heat can cause erosion of rocks |
OpenBookQA | OpenBookQA-4633 | organic-chemistry, biochemistry, color, electromagnetic-radiation
Title: How does UV affect skin colors in dark-skinned people? Skin color is one of the things one would rather not ask anything about! Only in humans, it can vary from very dark brown to pale pink. In darker-skinned people, the color is mainly due to melanin, which is produced by melanocytes.
There are three types of melanin: eumelanin, pheomelanin, and neuromelanin. Eumelanin is the most common; so it must be the reason of the dark skin of the dark-skinned. And that's true, since the two major groups of eumelanin are black and brown species.
The first ray produced by sun that comes to mind when you think about affecting the attributes of skin is UVA, since it penetrates most into the skin (Even though its energy is lesser than UVB). So, when I attach these two together I reach the fact that if UV rays do not cause free radicals they will eventually change the skin's color. (This is what is mostly believed and its effect on natural selection is impossible to hide)
Now, I give up. How does UV do to the skin that makes it darker? This must be very easy, huh? What am I missing? There is a journal article almost exactly about the title question, Mechanisms of Skin Tanning in Different Racial/Ethnic Groups in Response to Ultraviolet Radiation Journal of Investigative Dermatology (2005) 124, 1326–1332.
However, the body of the question assumes that eumelanin changes color. Instead, the article finds that melanin gets closer to the surface of the skin, and the degree to which this effect occurs varies with race/ethnicity.
The following is multiple choice question (with options) to answer.
Caribbean natives have a dark skin tone do to | [
"unicorns",
"solar radiation",
"lack of nutrients",
"camouflage"
] | B | radiation is when heat is transferred through waves |
OpenBookQA | OpenBookQA-4634 | acoustics, molecules, absorption
Title: How sound absorption results in heat? When sound passes through a medium (say, air) and hits the boundary atoms/molecules of another medium (say, a solid) ......
How would you continue the story ?
What happens at the interface in cases of absorption, transmission, and reflection and what is the difference in behavior (at a molecular level) at the interface in these cases ? Let's take water (and air) as an example.
Sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium (air and water in you example).
At the QM level, the vibrational energies of the water molecules could be interpreted as heat (temperature).
Molecules, such as oxygen (O2), have more degrees of freedom than single spherical atoms: they undergo rotational and vibrational motions as well as translations. Heating results in an increase in temperature due to an increase in the average translational kinetic energy of the molecules. Heating will also cause, through equipartitioning, the energy associated with vibrational and rotational modes to increase.
Now sound waves do carry energy, and that energy is transferred in part to the water.
Ultrasound is often said to be able to boil water. The reason is, soundwaves do carry energy as they pass through air, and then this soundwave passes into the water, and the energy carried by the wave itself will in part transform into the vibrational energies of the water molecules (heat).
In physics, attenuation or, in some contexts, extinction is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates.
Attenuation is what we call when the soundwave loses energy and that energy is transferred into the medium's (in your case water) molecules' vibrational energies (heat).
Please see here:
https://en.wikipedia.org/wiki/Acoustic_attenuation
When the sound wave hits the boundary of the media (air and water in your case), three things can happen:
elastic scattering (reflection or transmission)
inelastic scattering (heat)
absorption (heat)
The following is multiple choice question (with options) to answer.
Which would likely transfer special heat via waves? | [
"a cat",
"a rocket",
"a car",
"an atom bomb"
] | D | radiation is when heat is transferred through waves |
OpenBookQA | OpenBookQA-4635 | genetics, botany, seeds
Title: What DNA does a self-fertile plant's seedling have? Some plants are said to be self-fertile. An example is Prunus tomentosa.
Assuming that no cross-pollination happened with other plants, if a self-fertile plant such as prunus tomentosa produces a seedling, what DNA will the seedling have? Is the seedling's DNA an exact copy of the parent plant's DNA, or do the genes get rearranged? Selfing (aka self-fertilizing) differs from cloning. When selfing occurs, the offspring is not an exact copy of the parent. When cloning occurs, the offspring is an exact copy (except for a few mutations) of the parent.
Selfing implies that an individual will produce two gametes (typically a spermatozoid and an ovule but that might be a bit more complicated) and these two gametes are fusing to give the zygote (egg or offspring if you prefer).
As a consequence, when selfing, meiosis is occurring (and therefore segregation and recombination) so that the offspring is not an exact clone of the parent but rather some kind of a rearrangement of the parent genome (with a few mutations of course).
The following is multiple choice question (with options) to answer.
In the tree reproduction process a squirrel has the role of seed what? | [
"eater",
"scatterer",
"destroyer",
"killer"
] | B | In the tree reproduction process a squirrel has the role of seed disperser |
OpenBookQA | OpenBookQA-4636 | c++, error-handling, logging
const path LogFilePath = ( ( argc >= 4 ) ? path( argv[3] ) : defaultLogFilePath );
Log.open( LogFilePath.string() );
if ( !Log )
{
cerr << "Error creating " << absolute( LogFilePath ) << " : " << strerror( errno ) << endl;
return -1;
}
try
{
Snapshot( canonical( argv[1] ), canonical( argv[2] ) );
}
catch ( const filesystem_error& ex )
{
LogErrorStream << ex.what() << endl;
}
if ( Log )
{
if ( LogErrorStream.str().empty() )
{
cout << "The program ran without any errors.\n";
}
else
{
Log << "\nERRORS -:\n\n" << LogErrorStream.str() << endl;
cout << "There were some errors during the execution of this program !\n\nCheck " << absolute( LogFilePath ) << " for details.\n";
return -1;
}
}
}
The following is multiple choice question (with options) to answer.
Which would likely occur as a result of logging? | [
"an eagle and mouse compete for resources",
"an eagle and hawk compete for resources",
"an eagle and horse compete for resources",
"an eagle and tree compete for resources"
] | B | as the population of prey decreases , competition between predators will increase |
OpenBookQA | OpenBookQA-4637 | radiation
You see similar things happening here. The metal rod at the top of the lamp acts as a capacitive ground - given the very high voltage, a tiny charge will flow from the tip of the filament to the rod. There is a small amount of gas in the tube which is ionized and gives rise to the light you see. The electrons eventually bombard the metal "anode" and produce Bremsstrahlung - note that without the metal, you were getting a glow and no reading on the Geiger counter. There is a similar demonstration online which is more convincing in its use of conventional materials, but which otherwise shows many of the same phenomena.
It is almost certainly very inefficient. Most of the energy in an X-ray tube is converted to heat as the electrons burrow too deeply into the tungsten target for their radiation to escape- apart from the fact that only the most violent deceleration produces X-rays with high enough energy to penetrate the bulb and be detected.
I noticed that when the "alpha window" was removed, the reading in your video went up. Since there was also a biscuit tin and glass bulb in the way I suspect there was a lot more low energy radiation generated than was detected. Good stuff for skin cancer.
The experiment as shown should not be repeated. Not only were the HV precautions extremely poor, but so were the radiation safety precautions. Please don't try this at home...
The following is multiple choice question (with options) to answer.
A flashlight can be used to | [
"create warmness",
"become a firefly",
"travel to space",
"harvest magic"
] | A | a flashlight emits light |
OpenBookQA | OpenBookQA-4638 | spectroscopy, analytical-chemistry
A related technique that is much better suited to small handheld instruments is raman spectroscopy, since the light involved is actually usually in the NIR. I doubt this thing is sensitive enough to do it well, but it might be possible to add filters to the illumination and measurement ports to give it a shot. It's definitely possible to do raman with a handheld instrument though—I saw one of these at a conference recently. Quite expensive, but very nifty.
The following is multiple choice question (with options) to answer.
Where is a portable way of creating light most useful? | [
"pitch-black caverns",
"sunny days",
"a bright rooms",
"the sun"
] | A | a flashlight emits light |
OpenBookQA | OpenBookQA-4639 | # Heat Transfer
#### friendlyguyken
Ideally, when a thermometer is used to measure the temperature of an object, the temperature of the object itself should not change. However, if a significant amount of heat flows from the object to the thermometer, the temperature will change. A thermometer has a mass of 31 g, a specific heat capacity of 815 J/kg·°C, and a temperature of 12°C. It is immersed in 119 g of water, and the final temperature of the water and thermometer is 41.5°C. What was the temperature of the water before the insertion of the thermometer?
The answer posted by the instructor is 43 degrees C.
I am confused because I'm getting conflicting instructions from different sources, or maybe I'm just not understanding the full concept.
The instructor's way uses:
m1c1(Tf-Ti) = m2c2(Tf-Ti)
with this I got 40 degrees C.
Another source instructed to use:
m1c1(Tf-Ti) = m2c2(Ti-Tf)
with this I got 43 degrees C.
I do understand that Q=m1c1(Tf-Ti).
So, is the posted answer incorrect, or is the instructor's method incorrect, or is it just my calculation? Thanks and much appreciated! The attached image shows my work.
#### Attachments
• 264 KB Views: 7
#### oz93666
Pheeew ...Look at all those equations and numbers in your work , makes my eyes glaze over .... No need for it , just walk through the question step by step.....
The thermometer has mass 31 gm ,heat capacity 815/kg = 25.265J/C ...
Initial temp of thermometer is 12 final temp is 41.5 ..temp change is 29.5
That means the thermometer extracts 29.5 x 25.265 J = 745.3175J from the water.
thermal capacity of water 4.185 x119 = 498J/C
so how much will temp of water change if 745J is taken ???
745/ 498 = 1.5C ....gives the answer 43C
1 person
#### benit13
The following is multiple choice question (with options) to answer.
A thermometer would be used to | [
"determine if it is airier",
"determine if it is windy",
"determine the high tide",
"determine if it is hotter in the desert"
] | D | a thermometer is used to measure temperature |
OpenBookQA | OpenBookQA-4640 | soil-science
Title: How does humanure make soil "fluffier"? This BBC article says biosolids make soil "fluffier", among other benefits. How?
Adding humanure also changes soil structure, making it more resilient, preventing erosion and balancing out moisture, says Moss. It makes dirt fluffier, so water passes through easier. Conversely, in drought conditions, this also helps it retain water. The less compact soils are also softer, enabling seedlings to take faster and grow stronger roots, producing better yields. What are Biosolids and how do they work?
a biosolid is a product of the sewage treatment processes and is a semi-solid sludge of organic matter, nutrient-rich organic compounds. Here I list several reasons as to why biosolids would make the soil 'fluffier' and and better
As I said earlier biosolids are typically made out of organic matter, organic matter is carbon-based and biosolids are usually biological material (decomposed feces, urine and et cetera).
If you are not familiar with the normal decomposition processs it is a biological material (banana, apple, feces and et cetera) that is decomposed by microbes, molds, fungi and etc
biosolids are biological and/or organic material so what I just stated above applies to biosolids as well
Think of what you flush down a toilet or what goes down a sewer drain, are those things carbon based and biological? (human feces is an organic-compound and it goes in the sewers)
So now we know that biosolids are like other organic-compounds, how does this maker the soil fluffier. When something undergoes decomposition it turns into fresh brand-new soil, and quite obviously this new soil would be much more higher-quality and better than over-used old soil.
Here it states that organic material in a landfill produce gases due to decomposition so it makes sense that the same process would happen underground where microbial decomposition can release gases in the soil thus making the soil fluffier
So I can conclude that biosolids do, in fact help soil and make it fluffier and better.
The following is multiple choice question (with options) to answer.
What helps creates new material in the soil? | [
"network television",
"magnetism",
"wildfires",
"free radicals"
] | C | decomposition increases the amount of nutrients in the soil |
OpenBookQA | OpenBookQA-4641 | graphics, tex
%1: frame colour
\newcommand*{\addglasses}[1]{%
\path[draw=#1,line width=1] (0.93,1.62) -- (1.30,1.50);%
\draw[line width=1,color=#1] (0.73,1.67) arc (65:92:0.20);%
\path[draw=#1,line width=1,rotate=-20] (0.23,1.7675) circle (0.125);%
\path[draw=#1,line width=1,rotate=-20] (-0.06,1.74) circle (0.1143);%
}
\begin{document}
\begin{tikzpicture}
\duck{yellow}%
\addglasses{brown}%
\end{tikzpicture}
\end{document} Not much to say about the last version; on the other hand, you could exploit PGF keys.
\documentclass{article}
\RequirePackage{xcolor}
\RequirePackage{tikz}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% combine ducks
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\makeatletter
%1: skin colour
\newcommand*{\duck}[1][]{\tikzset{/duck/.cd,#1}\duck@draw}
The following is multiple choice question (with options) to answer.
Ducks might their webbed appendages to | [
"season pizza",
"navigate",
"sing",
"do ballet"
] | B | webbed feet are used for moving faster through water by aquatic animals |
OpenBookQA | OpenBookQA-4642 | climate-change, geography, rivers, rainfall, agriculture
Today Climate change and its consequences are some of the biggest challenges facing Humanity, with water scarcity being the big factor in Sub-Sahara Africa.
By Ultimately raising the Rainfall in the entire Southern Africa, through the managed and controlled filling and utilization of the Natural 30 000 - 60 000 square km of evaporation pans more regularly, will this not lower the extreme temperatures (day and night temperatures due to water absorbing much of the daytime heat and releasing it during the night) and drought patterns Southern Africa has experienced, and by all predictions are bound to worsen and could become more extreme?
In effect, creating a second Okavango Delta, but considerably bigger - large parts of Chobe.
A study of such a magnitude will need large amounts of research in multidisciplinary sciences, from Archaeology to Agriculture to Economics, and a much broader field of expertise - the biggest being Politics!
Could such a mammoth project not be but one small answer to a much bigger Climate Change challenge facing the Earth? (and ultimately send a bit of rain to my little piece of land in the Waterberg in the long dry winter months when we receive those dry West Winds - and fires become a serious hazard - simply by adding a bit of moisture from the vast pans Botswana are so blessed with!)
My mind has been going in circles as to the feasibility of such a mammoth, yet so cheap and easily implementable idea?
Any ideas? We agree that additional evaporation enhances energy transport from the surface to the atmosphere and intensifies the hydrological cycle and cloud formation, and that some of the most serious climate change issues such as:
The following is multiple choice question (with options) to answer.
If an environment experiences a long drought | [
"animals will experience a boom in reproduction",
"ponds may dry up and kill off the fish population",
"tadpoles will mature faster into frogs",
"plants will continue to flourish"
] | B | if the amount of available food and water decreases in an environment then animals may leave that environment to find food and water |
OpenBookQA | OpenBookQA-4643 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
Building which of the following would cause an animal exodus from the region? | [
"a conservatory",
"a park",
"a car dealership",
"a forest"
] | C | if the amount of available food and water decreases in an environment then animals may leave that environment to find food and water |
OpenBookQA | OpenBookQA-4644 | mechanical-engineering, structural-engineering, control-engineering
For example, if I wanted to setup such a facility, who would I have to consult?
You either find a consulting engineering firm with a lot of experience in designing and planning (and building!) such a plant. Or you find anexperienced hydroponics expert (the first bullet point) and a consulting firm with experience in a relevant field like wastewater.
Alternativly, you find a company specialized in building and selling hydroponics farms. This will give you less choice over the final plant - the company will want to work with their preferred components and concepts, and crucially they will want to reuse as much egnineering work from previous projects as they can.
The following is multiple choice question (with options) to answer.
Which would a strawberry most rely on to ensure it gets planted? | [
"a fish",
"a canary",
"a penguin",
"a tiger"
] | B | birds are a vehicle for spreading the seeds of a plant |
OpenBookQA | OpenBookQA-4645 | thermodynamics, water, phase-transition, phase-diagram
Title: Vaporization - phase diagram I understand what boiling and vaporization is. But what puzzles me is the phase diagram.
When I spill a glass of water in my room, it will soon vaporize, though there was normal atmospheric pressure and 20 °C. If you look in phase diagram of water, it should be still liquid at this point.
I understand that molecules of water escape the surface and turn into vapor, but... is the phase diagram of water wrong then? The temperature and pressure didn't change around that spilled water and still it turns into gas, although (looking at the phase diagram), it should be liquid. The phase diagram has equilibrium states for pure water, vapor, and both at saturation. You have water exposed to atmospheric gases, so the pressure is not that of pure vapor. The water will evaporate trying to create a partial pressure of vapor equal to the vapor pressure for saturated water at the water temperature. If the surface is open to flow of fresh air, this vapor pressure is not achieved, and the water slowly evaporates away.
The following is multiple choice question (with options) to answer.
The last stage of the water cycle is collection, after that is evaporation when water is transformed to vapor. What happens next? | [
"the water cycle flies",
"the water cycle repeats.",
"The water cycle stops",
"the water cycle nothing"
] | B | evaporation is when water is drawn back up into the air in the water cycle |
OpenBookQA | OpenBookQA-4646 | everyday-chemistry, water, absorption
Fig. B is complete speculation on my part as I did not return to the home during Winter to observe it. However in Spring when I returned, all of the tubs had experienced a change in their appearance.
All the tubs were now dry again, presumably down to evaporation due to increasing weather temperatures. And therefore releasing all that moisture back into the building again!
Three of the tubs were largely unchanged with some noticable "caking" together of the salt into crumbly, grainy lumps which returned to normal looking salt grains when crushed.
The most profound change from the remaining tubs was as you see in Fig. C of the diagram.
The salt had actually accumulated on the walls of the tub as a fine sediment. This suggests that water had accumulated in large amounts in the tub and had in fact risen higher than the original depth of the dry salt grains! I'd estimate that the tub would have had to accumulate about 0.5kg of water in order for the water/salt solution to reach the depth indicated by the dry sediment.
The salt had solidified into a single, large mass. The volume seemed to have increased noticeably but the density had also decreased accordingly, so the salt had basically expanded in it's container and solidified. It was crumbly and brittle and some of it had been reduced to a very fine sediment.
The home is a single storey, about 12m x 4.5m x 2.5m in volume.
My questions then:
Is this a valid technique for capturing excess moisture over Winter?
Are my observations and presumptions reasonable... Is Fig. B what really happened?
What is the chemistry / physics process that caused the salt to be transformed from Fig. A to Fig. C?
How many times did the tubs cycle between states B and C? Was it a single cycle that lasted all of winter, or a daily cycle following ambient weather temperatures? I could not tell just by looking at C on the last day of the experiment. According to Transportation Information Service: Salt:
The following is multiple choice question (with options) to answer.
In the morning, Rebecca saw some fluid in the gutter. Later, it was gone. What happened to it? | [
"condensation",
"evaporation",
"magic",
"deposition"
] | B | evaporation is when water is drawn back up into the air in the water cycle |
OpenBookQA | OpenBookQA-4647 | electrical-engineering, motors
Title: Avoid snapping an electric cable from too much rotation I recently built the basic construction for a crane out of lightweight material. Basically the head of the crane contains an electric servo motor which spins the head of the crane by pushing itself away from the tower (the rotor is fixed to the axis which is fixed to the tower. The axis isn't fixed to the head in any way).
All electronics required to operate the motor and more are inside the head. The only thing I should extend to the rest is a 240 V cable.
Since the head is allowed to make multiple rotations (preferably limitless), how do I avoid snapping my cable by rotating it too often? I'm aware such solutions exist, but I have no experience in this area so I have no idea what to ask for specifically.
/---------------------\
| |
| motor |
\----------|----------/
|
___________|___________
\ | /
\ | / The device you are looking for is called a slip ring such as the one shown below. These devices use internal components which maintain contact as they spin (old ones used brushes) allowing them to turn by an unlimited amount in either direction.
The following is multiple choice question (with options) to answer.
In order for a crane to operate properly it requires | [
"sand",
"the wind",
"solar power",
"a fulcrum"
] | D | a lever is used for moving heavy objects |
OpenBookQA | OpenBookQA-4648 | condensed-matter
Title: If a liquid is compressed enough, would it become solid? If a liquid were to be compressed so tensely that the particles had no room to move, would it then become a solid?
Also, would the same happen with a gas? It depends on the substance. It is easy to work out though from the relevant phase diagram.
Isothermally increasing the pressure of liquid CO$_2$ will create a solid phase (dry ice). But increasing the pressure of liquid water will not create ice.
A gas-to-solid transition with increasing pressure is a process called deposition. It will happen with most substances if the temperature is sufficiently low.
The following is multiple choice question (with options) to answer.
If a thing is going between liquid and solid, it is likely to | [
"visit a school",
"be a door",
"become less heavy",
"measure consistently"
] | D | phase changes do not change mass |
OpenBookQA | OpenBookQA-4649 | phase-transition, density, weight, matter, density-of-states
Title: What happens to weight when ice melts? A block of ice is weighed in a container. Then, it is left out to melt. Would the weight of the water be greater, less than, or equal to the ice?
I know that it has something to do with density and volume, but i'm not sure how. The internal energy if water is 80 calories per gram higher than that of ice, which represents a finite but incredibly small mass increase, as is clear from Einstein's relation E=mc$^2$. Otherwise the mass is constant. The weight depends also on the gravitational field, which you can assume to be constant over the volume of ice and water. All considered the weight should be the same to a very high accuracy.
The following is multiple choice question (with options) to answer.
If an ice cube that weighs 2 ounces melts, in liquid form, it will | [
"fly away",
"be 11 ounces",
"8 ounces",
"weigh the same"
] | D | phase changes do not change mass |
OpenBookQA | OpenBookQA-4650 | java, role-playing-game
//This is where the critter attack goes
/*
* d100();
*
* if (d100Result >= 0 && d100Result <= 20) {
*
* } else if (d100Result >= 21 && d100Result <= 40) {
*
* } else if (d100Result >= 41 && d100Result <= 100) {
*
* } else {
* System.out.println(there is an error here!");
* }
*
*/
d3();
switch (d3Result) {
case 1:
critterOffensive = true;
critterDefensive = false;
critterEvasive = false;
System.out.println("The " + critterName + " charges!");
System.out.println("Your children and the " + critterName + " are evenly matched!");
break;
case 2:
critterDefensive = true;
critterOffensive = false;
critterEvasive = false;
System.out.println("The " + critterName + " protects itself!");
System.out.println("Your children crush the " + critterName + "'s defenses!");
System.out.println("The " + critterName + " takes damage!");
critterHealth -= 1 * missionWorkerDrones + (missionWarriorDrones * 2);
break;
case 3:
critterEvasive = true;
critterDefensive = false;
critterOffensive = false;
System.out.println("The " + critterName + " moves quickly!");
System.out.println("Your children are outflanked by the " + critterName + "!");
System.out.println("One of your drones falls from it's wounds!");
d2();
switch (d2Result) {
case 1:
if (missionWarriorDrones > 0) {
killWarrior();
} else if (missionWarriorDrones <= 0) {
killWorker();
}
break;
case 2:
The following is multiple choice question (with options) to answer.
A koala's home can be destroyed because of | [
"affection",
"magic",
"my heart",
"exploding hot liquid"
] | D | if a habitat is destroyed then that habitat can not support animals |
OpenBookQA | OpenBookQA-4651 | astronomy
Title: Shining object in the sky resembling a star From last 2 days I am observing a shiny star like shining object in the sky in almost same place at same time. Is there any possibility that it could be a satellite? Will satellite shine like a star in the sky due to any kind of reflection from the sun. I see it in the evening and in white light. I don't know how to verify but I am very curious to know what it is. Bright "star" in the evening = Venus
http://www.universetoday.com/106160/bright-venus-takes-center-stage-in-november/
The following is multiple choice question (with options) to answer.
If a bright thing in the sky that is something other than our Sun does something in just under a month, it is likely | [
"the stars rising",
"the Sun burning",
"the air dying",
"luna cycling"
] | D | the Moon completes a lunar cycle over a period of 29 days |
OpenBookQA | OpenBookQA-4652 | newtonian-mechanics, forces, fluid-dynamics, reference-frames, drag
Title: Is drag force in the direction of particle motion or opposite to motion? Suppose water is flowing in horizontal direction (positive $x$-direction) and a particle immersed in that water is also moving in the same direction.
In this case, is the drag force $F_D$ in the direction of particle motion or opposite to it?
I get from wikipedia that drag force is a frictional force and hence is opposite to particle motion, but then what is the force that is making the particle move. Because in one journal paper, I see that drag force $F_D$ is shown as force in the direction of particle motion.
This is a sketch from the paper, you can see that flow velocity and drag force are both in the same direction. Drag force opposes the motion of a body relative to the surrounding fluid. In this case the surrounding fluid moves to the right and relative to that the solids move to the left.
The drag force is opposing the motion to the left, hence it is towards the right. The solids are being swept away by the fluid.
The following is multiple choice question (with options) to answer.
When fish travel in the opposite direction of flow they are going to | [
"spawn",
"party",
"site see",
"start over"
] | A | An example of a reproductive behavior is salmon returning to their birthplace to lay their eggs |
OpenBookQA | OpenBookQA-4653 | ecology, population-dynamics, predation
What seems to really remain to understand the evolution of cicada life cycles is to unravel the genetic mechanisms involved with timing.
Literature Cited
Goles, E. et al. 2001. Prime number selection of cycles in a predator-prey model. Complexity 6: 33-38.
Tanaka, Y. et al. 2009. Allee effect in the selection for prime-number cycles in periodical cicadas. Proceedings of the National Academy of Sciences USA 106: 8975-8979.
Williams, K.S. and C. Simon. 1995. The ecology, behavior, and evolution of periodical cicadas. Annual Reviews of Entomology 40: 269-295.
The following is multiple choice question (with options) to answer.
as the number of pollinators attracted to a flower increases , the ability to reproduce will increase for what? | [
"whales",
"oceans",
"flora",
"animals"
] | C | as the number of pollinators attracted to a flower increases , the ability of that flower to reproduce will increase |
OpenBookQA | OpenBookQA-4654 | entomology, ethology, habitat
Title: Preferred criteria for new bee colony location As a human I want a house with a roof, indoor plumbing, bug free, and make my wife happy. I don't want to drive too far to work, and it has to be well-suited for offspring.
What are the criteria that define a "good spot" for a new location for honey bees. I'm sure it involves water, shade, access to nectar, and defensibility, but I don't know any of the details.
Has anyone ever made measures of this? Beekeepers? Apiologists? What are the things bees think are important, and what values of those do they think are "best"? According to Thomas Seeley, in his book, Honeybee Democracy, he gives the following as important criteria for honeybees when selecting a nest site when a bee colony moves to swarm:
Larger volume (the minimum nesting capacity was found to be around 14 liters with more preference to nests with a capacity of approximately 30 to less than 100 liters)
Relatively small entrance (10 to 30 centimeters squared)
Nest with the entrance located near the floor of a tree cavity
Direction of the nest entrance (south facing for thermoregulation during the winter)
Nest height (preference given to higher nests for colony defense)
Remnants of previous honeycombs (saves work and energy in building the nest structure)
Interestingly enough, bees did not necessarily display a preference for the shape of the entrance, the shape of the nest, the draftiness or dryness of the nest cavity (they are able to plug and waterproof nests).
Flower/nectar/food availability is not necessarily a direct factor as this changes quite frequently throughout the seasons and honeybees are not able to leave their honey stores (which are necessary to sustain the colony throughout the winter) or take them with them every time the colony has trouble finding food. Honeybees have a complex and efficient system for optimized location and sharing of food sources, therefore distance is not as large a factor.
The following is multiple choice question (with options) to answer.
The more bees a dandelion entices the more it | [
"gets written about",
"succeeds in reproducing",
"becomes a rose",
"becomes wine"
] | B | as the number of pollinators attracted to a flower increases , the ability of that flower to reproduce will increase |
OpenBookQA | OpenBookQA-4655 | zoology, pathology
Title: Why don't people seem to die from salmonella in bites? As far as I know, reptiles have salmonella in their mouths as part of their digestive process. Every time I hear about someone being bitten by an python or alligator or monitor either at a zoo or in the news or from a private owner, it seems like whoever is bit recovers with ease.
How come something as virulent as salmonella that can evade an immune response doesn't cause whoever gets bitten to nearly immediately become septic? Is it because salmonella only attacks epithelial tissue and there isn't much of that deep in an arm or leg? Salmonella infect via the fecal-oral route. They have proteins on their surface that match our gut cell surfaces, allowing them to attach and invade the gut. Those cell markers aren't present when you are bitten. it's the same reason that plant virus dont make us sick.
https://www.ncbi.nlm.nih.gov/pubmed/17593246
this is a bit heavy if you dont usually read primary papers, but looking for "Salmonella route of infection" or similar will yield the same kind of information
The following is multiple choice question (with options) to answer.
Listeria can make you | [
"into raw meat",
"tread water",
"aroused",
"feverish"
] | D | bacteria can cause people to become ill |
OpenBookQA | OpenBookQA-4656 | immunology, bacteriology
Title: How do infectious bacteria determine when their numbers are high enough to attack a host? When you get sick, you generally don't contract enough bacteria at once for them to succeed in battling your immune system, right? Their numbers must gradually increase in the host's body before they know that they can attack. How does that work? I think the current answer to this for bacterial infections is quorum sensing. Quorum sensing is a signalling pathway in bacteria which senses a molecule that the bacteria themselves secrete. When the concentration of the quorum signal reaches a certain level, the bacteria interpret this as their population density reaching some threshhold.
Bacteria are always around - even infectious Staph, as described in the other answer, the bacteria are always being cleared out by the immune system, but when they find the right place where they can get critical mass, they dig in, form a biofilm and secrete toxins, which can help them divide more successfully.
This is a description of the process from a paper on Staph infection, a common bacterial infection in humans.
The following is multiple choice question (with options) to answer.
Bacteria can cause people to become what? | [
"unwell",
"energetic",
"vibrant",
"healthy"
] | A | bacteria can cause people to become ill |
OpenBookQA | OpenBookQA-4657 | Let $a_n$ be the time at which the $n$th bullet strike occurs. We have $a_1=x_0/v_0$ and $$\begin{equation*} v_0(a_n-(n-1)T) = v_0(a_{n-1}-(n-2)T) + v(n-1)(a_{n}-a_{n-1}) \end{equation*}$$ In words, the distance between the block and the gun at the $n$th strike is the distance between the block and the gun at the $(n-1)$th strike plus the distance the block travels between the strikes. Rearranging we find $$a_n = a_{n-1} + \frac{p+n-1}{p} T$$ as claimed. This recursion can be solved by standard techniques. We find $$a_n = \frac{x_0}{v_0} + \frac{(n-1)(n+2p)}{2p} T.$$ As a consistency check we take the limit where $p$ is large. Then $$a_n \sim \frac{x_0}{v_0} + (n-1)T.$$ This is the result we should expect for bullets fired at an immovable wall.
The following is multiple choice question (with options) to answer.
You can make an untraceable bullet with | [
"metal",
"alloys",
"lead",
"frozen water"
] | D | freezing causes a solid to form |
OpenBookQA | OpenBookQA-4658 | electricity
The tingling persisted when he stood on a plastic stool instead of the sofa.
The tingling did not appear when we plugged the iPod into a power outlet at a hotel we later visited in a different city in China.
Unfortunately, I am no longer in China, so I will not be able to conduct additional tests. Does anyone have a scientific explanation for this phenomenon as well as what might cause it to occur only occasionally? You are feeling an electric current because the "live" wire of the electrical outlet is (capacitively) connected to the "ground" of your phone.
The same effect can sometimes be felt in the US (or wherever "back home" is for you) with an improperly wired desk lamp - or one that has an unpolarized plug (so you can plug it in "backwards" - that is, with the wire that should be neutral getting the AC fluctuations of the live wire and vice versa).
The electric field induces a small current in you because your body has a capacitance relative to "the world". You don't need to close the circuit - it is enough to touch the object (a conductive part like the external antenna). That is why standing in a plastic chair doesn't make it go away.
The amount of charge flowing is small (because your body's capacitance is small and the voltage is not that high) - but the effect is real. And it usually means something is off with the wiring: in a well designed and built system this should not happen.
Most recently I noticed the same thing using an Apple MacBook Air plugged in to an outlet in Europe. The frame of the laptop gave the same buzz. And this was a "genuine Apple component".
I believe it is harmless. But real.
The following is multiple choice question (with options) to answer.
If standing on sparking wires, you feel nothing because | [
"you have sneakers on",
"you are simply immune",
"you have a hard hat on",
"you have pants on"
] | A | an electrical insulator slows the transfer of electricity |
OpenBookQA | OpenBookQA-4659 | experimental-physics, radiation, geometric-optics, spectroscopy, radiometry
If possible, I highly recommend adding a single bi-convex lens to your optical system (possibly achromatic for broadband use, or you could use an elliptical silver mirror). If you put the source and the spectrometer slit at $2f$ distance from the lens on either side, you will be imaging your source onto your slit, and it will remove a lot of the uncertainty in your estimate.
Good luck!
The following is multiple choice question (with options) to answer.
Which setup likely refracts light? | [
"a banjo and a flute",
"two mirrors in unison",
"a cat in a hat",
"gems and glowlights arranged precisely"
] | D | a prism refracts light |
OpenBookQA | OpenBookQA-4660 | evolution, ornithology, palaeontology
One thing those many, many bird and proto-bird fossils also made clear is that the traits of modern birds (feathers, wings, toothless beaks, etc) didn't evolve in a simple line from non-bird to bird. Many of those traits evolved convergently in several lineages, were lost in some, maybe regained in others, and feathers in particular turn out to be a widespread dinosaur feature that cannot be considered a uniquely bird trait anymore (unless we want to call T-rexes "birds"). Still, saying "beaks evolved several times" or "feathers evolved several times" doesn't mean that birds, let alone modern birds, evolved from several different ancestors. It can mean that the common ancestor of birds had lots of variously bird-like more-or-less distant cousins living around the same time.
The following is multiple choice question (with options) to answer.
Depending on the type of bird, it could have different what when compared to another bird | [
"restaurant",
"nothing",
"space",
"sustenance preferences"
] | D | birds with beaks of different shapes eat different foods |
OpenBookQA | OpenBookQA-4661 | metabolism, nutrition, digestive-system
Title: Do I have to chew for digestion to kick in? Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"? If you had to chew to digest, then beverages like sugary sodas would never be digested or provide calories or nutrients, as you (generally) don't chew when you drink them. No, chewing is not required for digestion or nutrient absorption. Chewing is important when eating solid foods, as the chewing action breaks down and begins to solublize the food, and stimulates the production of saliva, which contains enzymes that begin to break down the food prior to digestion in the stomach and intestines.
The following is multiple choice question (with options) to answer.
The digestive system digests what for the body? | [
"water",
"metal",
"sustenance",
"rocks"
] | C | the digestive system digests food for the body |
OpenBookQA | OpenBookQA-4662 | [13]:
nutrients = pd.DataFrame(
index=[
"Vitamin A",
"Vitamin B1",
"Vitamin C",
"Calcium",
"Iron",
"Phosphorus",
"Potassium",
"Total fat",
"Carbohydrates",
"Proteins",
]
)
nutrients["DRI"] = [800, 1.1, 80, 800, 14, 700, 2000, 70, 260, 50]
nutrients["Chicken Breast"] = [0, 0.1, 0, 4, 0.40, 210, 370, 0.8, 0, 23.3]
nutrients["Milk"] = [37, 0.04, 1, 119, 0.1, 93, 150, 3.6, 4.9, 3.3]
nutrients["Pasta"] = [0, 0, 0, 22, 1.4, 189, 192, 1.4, 79.1, 10.9]
nutrients["Beans"] = [3, 0.4, 3, 135, 8, 450, 1445, 2, 47.5, 23.6]
nutrients["Oranges"] = [71, 0.06, 50, 49, 0.2, 22, 200, 0.2, 7.8, 0.7]
nutrients
[13]:
DRI Chicken Breast Milk Pasta Beans Oranges
Vitamin A 800.0 0.0 37.00 0.0 3.0 71.00
Vitamin B1 1.1 0.1 0.04 0.0 0.4 0.06
Vitamin C 80.0 0.0 1.00 0.0 3.0 50.00
Calcium 800.0 4.0 119.00 22.0 135.0 49.00
Iron 14.0 0.4 0.10 1.4 8.0 0.20
Phosphorus 700.0 210.0 93.00 189.0 450.0 22.00
Potassium 2000.0 370.0 150.00 192.0 1445.0 200.00
Total fat 70.0 0.8 3.60 1.4 2.0 0.20
Carbohydrates 260.0 0.0 4.90 79.1 47.5 7.80
Proteins 50.0 23.3 3.30 10.9 23.6 0.70
The following is multiple choice question (with options) to answer.
A load of nutriment, when consumed, will be | [
"tilled in the soil",
"burned in a fire",
"utilized internally by something",
"made into golden wheat"
] | C | the digestive system digests food for the body |
OpenBookQA | OpenBookQA-4663 | everyday-chemistry, water, absorption
Fig. B is complete speculation on my part as I did not return to the home during Winter to observe it. However in Spring when I returned, all of the tubs had experienced a change in their appearance.
All the tubs were now dry again, presumably down to evaporation due to increasing weather temperatures. And therefore releasing all that moisture back into the building again!
Three of the tubs were largely unchanged with some noticable "caking" together of the salt into crumbly, grainy lumps which returned to normal looking salt grains when crushed.
The most profound change from the remaining tubs was as you see in Fig. C of the diagram.
The salt had actually accumulated on the walls of the tub as a fine sediment. This suggests that water had accumulated in large amounts in the tub and had in fact risen higher than the original depth of the dry salt grains! I'd estimate that the tub would have had to accumulate about 0.5kg of water in order for the water/salt solution to reach the depth indicated by the dry sediment.
The salt had solidified into a single, large mass. The volume seemed to have increased noticeably but the density had also decreased accordingly, so the salt had basically expanded in it's container and solidified. It was crumbly and brittle and some of it had been reduced to a very fine sediment.
The home is a single storey, about 12m x 4.5m x 2.5m in volume.
My questions then:
Is this a valid technique for capturing excess moisture over Winter?
Are my observations and presumptions reasonable... Is Fig. B what really happened?
What is the chemistry / physics process that caused the salt to be transformed from Fig. A to Fig. C?
How many times did the tubs cycle between states B and C? Was it a single cycle that lasted all of winter, or a daily cycle following ambient weather temperatures? I could not tell just by looking at C on the last day of the experiment. According to Transportation Information Service: Salt:
The following is multiple choice question (with options) to answer.
Lucy left a pan half full of water in the sun and it dried up in one afternoon. | [
"the pan was in the cool shade",
"a squirrel dumped the water of its head to cool off",
"butterflies drank it all",
"it was the summertime"
] | D | An example of evaporation is a body of water drying up by absorbing heat energy |
OpenBookQA | OpenBookQA-4664 | physical-chemistry, water
$$\ce{CaSO4 + 2 H2O -> CaSO4.2H2O}$$
Thus, your dry $\ce{CaSO4}$ will absorb water from the environment, becoming a drying agent. You may regenerate it by reheating it to $\pu{393 K}$, and so on and so forth.
The following is multiple choice question (with options) to answer.
An example of evaporation is a body of water drying by by absorbing what energy? | [
"hotness",
"electrical",
"cool",
"chilly"
] | A | An example of evaporation is a body of water drying up by absorbing heat energy |
OpenBookQA | OpenBookQA-4665 | thermodynamics, energy, temperature, estimation
Title: What would happen if a 10-kg cube of iron, at a temperature close to 0 kelvin, suddenly appeared in your living room? What would be the effect of placing an object that cold in an environment that warm? Would the room just get a little colder? Would it kill everyone in the room like some kind of cold bomb? What would happen?
Don't think about how the cube got there, or the air which it would displace. Nothing overly dramatic, though it would be cool to look at. The cube would very quickly become covered by a layer of nitrogen/oxygen ice as the air which came into contact with it froze. Further away, you'd see condensation of water vapor into wispy clouds, which would swirl around the block due to the air currents generated by the sudden pressure drop.
Other than that, as long as you aren't in immediate thermal contact with the block, you wouldn't notice much other than that the room cools down. Here's a video I took of a vacuum can that was just removed from a dewar of liquid helium at 4 kelvin. It's maybe 5 kg of copper, not 10 kg of lead, but I'd say that's close enough to get the idea.
You can see one of my coworkers climbing down into a pit below it; he had to be careful not to bump his head on it, which would have really ruined his day, but there was no fatal cold bomb :)
The following is multiple choice question (with options) to answer.
Which would freeze last? | [
"a thimble of water",
"a pond of water",
"a glass of water",
"an ocean of water"
] | D | adding salt to a solid decreases the freezing point of that solid |
OpenBookQA | OpenBookQA-4666 | reaction-mechanism
It is generally said that reactants react so that they can achieve a
lower energy state. Then why does a reversible reaction occur in the
first place?
Good question. Remember that we can always add energy to make an unfavorable reaction proceed. For example, the sodium ion, which is isoelectronic with neon, is stable with a full octet of electrons. However, we can still take away more electrons. It just takes a rather sizable application of energy.
The following is multiple choice question (with options) to answer.
A chemical reaction can be caused by | [
"pouring soda into milk",
"putting vinegar in a bowl",
"bleach vinegar combo solution",
"pouring baking soda out of a box"
] | C | baking soda can react chemically with vinegar |
OpenBookQA | OpenBookQA-4667 | wildfire
There are detailed satellite imagery with PM2.5 monitor overlay at Aerosol Watch, if you would like to see how the event progressed through time.
The following is multiple choice question (with options) to answer.
Controlled burns help prevent wildfires by cleaning up | [
"dead foliage",
"animal droppings",
"wasp nests",
"air pollution"
] | A | fire destroys plants in an environment |
OpenBookQA | OpenBookQA-4668 | 5. So you have the distance in terms of two functions in t and you can plug those functions of t into your distance formula, then you derive it and plug in the value of 2 mins. (keep in mind that your rate is in hours and your t value is in minutes so I converted 90 km/h to 3/2 km/min by dividing by 60 and similarly converting 80km/h to 4/3 km/min.
I guess and easier approach would be to plug in before deriving so you have:
distance = $\sqrt{\left( 5\; -\; \frac{3}{2}t \right)^{2}\; +\; \left( 5\; -\; \frac{4}{3}t \right)^{2}\; }$
then simplifying you get: distance = $\sqrt{\frac{145}{36}t^{2}\; -\; \frac{85}{3}t\; +\; 50\; }$
Derive that with respect to t to get:
D(distance) = $\left( \frac{1}{2} \right)\frac{\left( \frac{145}{18}t\; -\; \frac{85}{3} \right)}{\sqrt{\frac{145}{36}t^{2}\; -\; \frac{85}{3}t\; +\; 50}}$
I derived that using first the power rule $d\left( x^{p} \right)\; =\; px^{p-1}$ and the chain rule: $d\left( f\left( g\left( x \right) \right) \right)\; =\; f'\left( g\left( x \right) \right)g'\left( x \right)\; dx$
Then plug in your value of t = 2 min to get the answer.
The following is multiple choice question (with options) to answer.
To calculate distance divided by time you would need a | [
"multi-meter",
"speedometer",
"Geiger counter",
"seismograph"
] | B | speed is a measure of distance travelled divided by time |
OpenBookQA | OpenBookQA-4669 | javascript, css, validation
Ask the right people the right questions
Last but not least, defining what is a strong password depends on many things. If in doubt, pay the people over at Security a visit, that's what they're there for.
The following is multiple choice question (with options) to answer.
Thicker layers of skin would best suit | [
"a bird",
"a scorpion",
"a lizard",
"a leopard seal"
] | D | as the thickness of an object increases , the resistance to damage of that object will increase |
OpenBookQA | OpenBookQA-4670 | mass, velocity, weight
Title: Feathers and Human Flight In the case of Angels where they're supposed to have wings full of feathers and can fly. If we created a flight suit for humans made out of feathers, how big would the feathers have to be?
If the feathers got scaled up would it make it impossible for flight?
If you wanted to flap in order to gain lift, how much weight would be on each arm due to the feathers and how much would you have to flap to gain thrust?
I don't know whether this is the correct forum for this question - it's sort of half biology half physics. To be honest I'm more interested in the maths and physics behind this question. ##Short:##
Given enough assumptions to make the question answerable.
Feather size:
Probably 300 to 500 mm for a small percentage of the feathers
and closer to 50% of that for the majority
Power and force:
Without a complex analysis of flapping flight (with takeoff mode, soaring versus "hovering" capabilities and more) a definitive answer would be difficult, but given the assumptions below, a rough scaling of power with mass seems appropriate, wing loadings (flight mass per area) can be similar and the use of available stronger-than-original non-biological materials should allow an approximately linear scaling of flight-hardware mass with total lifted mass. Power levels required for takeoff appear to be well in excess of those achievable from available human biological sources - something confirmed by all human experience to date.
However, the example of birds such as the Great Albatross and the Wandering Albatross indicate that both power and energy levels required for very long range soaring mode flight should be achievable by human biological power plants. Learning how to do this at all, let alone while sleeping, is yet to be mastered.
Because - read on ...
The following is multiple choice question (with options) to answer.
Thick feathers can be used to stay what? | [
"frigid",
"frosty",
"freezing",
"toasty"
] | D | thick feathers can be used for keeping warm |
OpenBookQA | OpenBookQA-4671 | evolution, ornithology, palaeontology
One thing those many, many bird and proto-bird fossils also made clear is that the traits of modern birds (feathers, wings, toothless beaks, etc) didn't evolve in a simple line from non-bird to bird. Many of those traits evolved convergently in several lineages, were lost in some, maybe regained in others, and feathers in particular turn out to be a widespread dinosaur feature that cannot be considered a uniquely bird trait anymore (unless we want to call T-rexes "birds"). Still, saying "beaks evolved several times" or "feathers evolved several times" doesn't mean that birds, let alone modern birds, evolved from several different ancestors. It can mean that the common ancestor of birds had lots of variously bird-like more-or-less distant cousins living around the same time.
The following is multiple choice question (with options) to answer.
Some birds have adapted to their cold environment by over time evolving to have thicker feathers in order to | [
"go to space",
"avoid freezing",
"eat dinosaurs",
"nothing"
] | B | thick feathers can be used for keeping warm |
OpenBookQA | OpenBookQA-4672 | rtabmap
I'll look into that.
EDIT: Question with solution to this new problem
The problem has been solved by adding to the launch file:
<node pkg="nodelet" type="nodelet" name="stereo_nodelet" args="manager"/>
as suggested by user matlabbe above.
See comments to question for more details
Originally posted by AlessioParmeggiani with karma: 165 on 2022-02-08
This answer was ACCEPTED on the original site
Post score: 0
The following is multiple choice question (with options) to answer.
Amoebas have zero options and must preform | [
"zero duties",
"most duties",
"all responsibilities",
"some duties"
] | C | if a cell can not specialize then that cell must perform all life functions |
OpenBookQA | OpenBookQA-4673 | acoustics
It has a lot of mass, too.
If you were to persuade your elephant to lean on a resonant wall, it would damp the wall to some extent, depending on how hard it squished itself against it. It would be acting like the world's biggest lump of rockwool or neoprene rubber. It wouldn't really be fabulously efficient used in this manner.
If, however, we were to replace the wall with entirely elephant, you would very probably have a really, really good sound insulator. 8ft of varying densities & substrates, a lot of mass & not a lot of cohesion between each component & its resonant frequency. If we were to get a bit 'icky' then its lungs & rib cage would probably be the most resonant part - so let's wedge him into the wall facing the noise, & we can sit quietly in the room his butt protrudes into.
Sonic bliss, if not olfactory ;)
Note: I've not even touched on reflectivity or diffusion - that would turn this into a full novel ;))
After comments
It is remarkably difficult to achieve total sonic separation in a domestic environment. I once built a 'room within a room' as a home recording studio, in a house basement, of course surrounded by earth - lots of mass. I did manage to achieve sufficient reduction that you could no longer hear anyone shouting or singing as loud as they possibly could, from the room above. My bass (guitar) amp, however, still went through it like a knife through butter. It took the extra attenuation of the building [double skin of old Victorian brickwork] & earth itself to fully damp it to below audibility. You couldn't hear it from outdoors unless it was particularly quiet in the street.
The following is multiple choice question (with options) to answer.
If one is hitting ebony and ivory and making sound | [
"that is a kitchen utensil",
"that is an instrument of pain",
"that is a scientific instrument",
"that is playing Chop sticks"
] | D | An example of playing a musical instrument is hitting the keys of a piano |
OpenBookQA | OpenBookQA-4674 | sea-level, tides, seasons, flooding
Title: How was Venice flooded? If I understand this correctly, Venice was not flooded due to sudden rainfall causing rivers to overflow, but due to the high tides. These high tides were caused by an alignment of sun, which was expanding the waters of the oceans disproportionately on one hemisphere and moon, which shifted the center of gravity of the moon-earth system in such a way that water rose on the same hemisphere.
In the news articles that I see, they also mention strong winds. This would make sense. High baseline + waves = a lot of water in the city. But in these photos everything seems to be calm. No waves, no wind, just an abnormally high level of water:
https://www.theatlantic.com/photo/2018/10/venice-under-water/574396/?fbclid=IwAR1DWLs_W39ndpdLWLZ1f6wlDDw8ZJmcBqyVM555O9DL5a_DhuY0mPQDi38
For me this doesn't make any sense. If the winds subsided and the flooding was caused purely by tidal effects, which are astronomical events, shouldn't it have been predictable months, if not years in advance?
If the winds subsided and the flooding was caused purely by tidal effects, which are astronomical events, shouldn't it have been predictable months, if not years in advance?
The following is multiple choice question (with options) to answer.
a flood is occurring there was most likely | [
"light hail",
"clear skies",
"some leaves",
"great drops repeating"
] | D | when a river floods , that river deposits sediment in flood plains |
OpenBookQA | OpenBookQA-4675 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
More dirt and sand gets deposited in a flat area near a river whenever | [
"the river is hit with an extremely large amount of precipitation in a day",
"a deer is hunted on the river bank",
"birds fly over the area",
"a helicopter flies too low over the land"
] | A | when a river floods , that river deposits sediment in flood plains |
OpenBookQA | OpenBookQA-4676 | adaptation
Title: How do longleaf pine trees adapt to the florida keys rainforest? I know that longleaf pine trees can be found in rainforests, but I can't find anything. This is sort of a too broad question but here are a few ideas. The second most fragile part of plants are the leaves. In the latitudes and elevations that experience freezing, plants have learned to abscise their leaves and go dormant for the winter season. Conifers have thick, waxy, very thin leaves that most conifers do not need to shed.
In a rainforest there is no danger of too cold temperatures. That is why there is an abundance of broadleaf trees and plants in the rainforest. Most of our indoor plants are tropical rainforest species.
There is also an awful lot of rain in a rainforest. There is a problem with leaves covered with water, as it inhibits the absorption of CO2. Beneath the leaf, O2 is released as a by-product of photosynthesis. Broad leafed plants that have adapted to an environment with lots of rain, little wind, and being crowded together have leaves designed to 'wick' the rain water off the leaf to run down the midrib and off the pointy tip or lobed or curled under leaf margins. This clears off the water and allows the plant to take up CO2, or it would not be able to do photosynthesis to make its own food for energy.
The other cool thing I can remember, is that broad leafs of plants are able to 'adjust' to the light. Similar to a 'solar sail' in outer space. If in full sun, those leaves get thick and stay smaller. If in shade, very normal in a rainforest, those leaves can thin and get larger in order to capture as much light as possible.
A better wording for your question would be, 'why is there an abundance of broad leaf species versus conifers in a rainforest'? If I've been able to translate your question correctly?
Hope this helps.
The following is multiple choice question (with options) to answer.
If the part of a tree that contains chloroplasts has flatter surfaces they have more | [
"vibrant colors",
"absorbing mass",
"life",
"friends"
] | B | as flatness of a leaf increases , the amount of sunlight that leaf can absorb will increase |
OpenBookQA | OpenBookQA-4677 | climate, seasons, ice-age, axial-obliquity
Image originally from The Petroleum System Blog
Using that formula, the temperature at the poles (reduced to sea level) would be -16.8 °C (from the figure actual data points it can be seen that in real life the south pole is much colder than the north pole).
Now, the previous assumptions contradicts the requirement of "equilibrium", because the above scenario is far from steady state.
So now I will go on to try to describe what would happen to Earth's climate in your hypothetical scenario:
One thing that we learned by studying how the Milankovitch cycles trigger and reverse Pleistocene ice ages, is that to initiate an ice age cold winters are not necessary, what is needed are cold or mild summers.
Currently, the inclination of Earth axis (a.k.a. obliquity) varies between 22° and 24.5° , with a mean period of 41,040 years. When the inclination is 22°, mild summers occur and, therefore, the perfect condition to initiate an ice age (specially when combined with other ad-hoc orbital conditions). The permanent equinox situation you propose, is equivalent to an obliquity of 0°, that would lead to the coldest possible summer (this is, no summer at all). Therefore, such condition would set the Earth on track for an intense and never-ending ice age.
Let me explain how this could work: Using the formula above, the temperatures would be permanently below zero between the poles and latitudes 58.3°. Therefore, snow would start to accumulate in those areas, building an ice sheet and once the ice sheet gets thick enough it would start flowing outwards.
Figure from Lumen Learning.
The ice sheet then becomes self-sustaining due to two positive feedbacks:
Due to its high albedo, it would reflect most of the solar radiation back to the space, cooling down the Earth.
As the ice sheet advance, its thickness adds to the elevation of the terrain, therefore the surface is higher and colder, allowing snowfall beyond the 58.3° of latitude. The thicker it grows the more it can advance towards the equator.
The following is multiple choice question (with options) to answer.
If an scientist is stationed in the south pole during their winter, what season is it in the arctic region | [
"Fall",
"Winter",
"Summer",
"Spring"
] | C | snow falls during the winter in the arctic environment |
OpenBookQA | OpenBookQA-4678 | botany, plant-physiology, reproduction, plant-anatomy, life-history
In dimorphic cleistogamy CL and CH flower differ in the time or place
of production, with CL flowers produced in conditions (underground,
low light levels, early in the season) that are potentially
unfavorable for outcrossing.
In induced cleistogamy potentially CH flowers that experience conditions such as drought or low temperatures fail to open and self-pollinate, becoming, in effect, CL flowers.
You should check out the Culley and Klooster (available online if you make a jstor login) – they discuss complete cleistogamy which addresses your last question. They report several completely CL species in their Table 1, and give references.
More generally, many different plant groups maintain balances of self-pollination and outcrossing (i.e. "real sex"), through an even more diverse set of mechanisms.
Even more generally, many plants and some animals maintain balances of sexual reproduction and clonal reproduction, through an even more diverse set of mechanisms. For instance, vegetative reproduction (e.g., strawberry runners) is very common in many plant groups; facultative and obligate parthenogenesis in animals also occurs.
Culley, Theresa M. and Matthew R. Klooster (2007). The Cleistogamous Breeding System: A Review of Its Frequency, Evolution, and Ecology in Angiosperms. Botanical Review. Vol. 73, No. 1, pp. 1-30
The following is multiple choice question (with options) to answer.
Bees are key to a flowers | [
"procreation",
"water supply",
"sun intake",
"color"
] | A | A bee is a pollinating animal |
OpenBookQA | OpenBookQA-4679 | species-identification
Title: What bird / animal has this call? USA MA NE
I have a bird / animal coming to the trees in the backyard making this call (see link to audio file), which does not really sound like a bird - it's fairly low frequency. I have not seen it. Sometimes it sits in a young tree, where you can almost see through to the trunk. But I cannot make it out, so it's not very big (like a turkey). It comes at late afternoon and stays around until ~11PM. It switches trees fairly quickly, so I assume it can fly. The call is always the same. Sometimes another one of its kind answers.
Bird_animal_call_mp3
You don't need dropbox. Ignore "suspicious link". Close login popup. Click download arrow. Direct download.
I added a Soundcloud link:
Bird_animal_call_mp3 It is a grey tree frog's mating call. See youtube link:
Grey tree frog mating call
Source for finding the answer: Audubon Society
The following is multiple choice question (with options) to answer.
Which animal interacts most with a peony? | [
"human",
"bee",
"elephant",
"worm"
] | B | A bee is a pollinating animal |
OpenBookQA | OpenBookQA-4680 | newtonian-mechanics, energy-conservation, momentum, conservation-laws
So the answer is that regardless of the current motion of $M$ it is always possible to shoot $m$ at $M$ such that it transfers all its kinetic energy to $M$ and thus the maximum amount is 100%.
The following is multiple choice question (with options) to answer.
A thing which has great physical capacity is most likely | [
"hardly healthy",
"in poor health",
"in fantastic health",
"rarely healthy"
] | C | being stronger usually has a positive impact on an living thing 's health |
OpenBookQA | OpenBookQA-4681 | human-biology, mammals, lifespan, dogs, rodents
Gigantism:
Whilst the life expectancy for a species may be higher in general people with gigantism may live shorter lives than possible because of non-metabolic related reasons. For example many forms of gigantism are linked to hormones which promote cell division and growth which are also linked to forms of cancer.
The following is multiple choice question (with options) to answer.
Bears will always have longer life cycles than a | [
"tortoises",
"whales",
"elephants",
"fox"
] | D | being stronger usually has a positive impact on an living thing 's health |
OpenBookQA | OpenBookQA-4682 | air-pollution
Title: Less pollution: moving hurricane debris to other regions for use, or burning? When a big hurricane hits, it can create debris on the scale of $\mathrm{10^8 yd^3}$. Cities in Florida, Texas, and other affected areas are struggling to hire enough trucks and drivers to pick it up quickly. But aside from that, I noticed many of the areas have started to burn the debris once it starts building up.
Got to wondering... typically mulch comes in modestly pricey, and when free mulch is offered, it often goes quickly.
So assuming a fair portion of debris is mulchable and is of interest to other areas, and that we can acquire typical transportation resources, then we'll set up transfer from collection sites to those other regions rather than burning it. What would be the net pollution result?
If removed for mulch and such: trucking pollution + decomposition (- trees saved locally??)
If burned: the burning pollution.
Obviously it's about approximation rather than exacts, it's probably hard to appraise the different byproducts from burning versus decomposition, and a lot probably depends upon the way it is burned. But as a whole, can we get a rough estimate of comparable quantities/damage done... is it less pollution/damage even to truck it an average of 3000 miles? 1000 miles? 100 miles? 10 miles? Should it be burned on the spot (if done safely)? Would think there's got to be some way to get a very rough idea.
Certainly the best option if viable might be leaving it in place to decompose. But considering how upset people are getting at having debris around these parts a month later, exclude that option from the possibilities.
Trucking or burning, how do they compare? As the question was changed, my answer attempts to evaluate only the difference between burning and transporting. Please correct my values if my quickly found sources are inaccurate or you find more representing. I know there is quite a few unwritten assumptions that simplify this problem.
The following is multiple choice question (with options) to answer.
Which is the best thing to do for an environment? | [
"growing roses and weeding",
"introducing a new species",
"planting trees to replace fallen ones",
"spreading trash and garbage"
] | C | a tree can be replaced by planting a new tree |
OpenBookQA | OpenBookQA-4683 | botany, terminology, trees
Title: Branch taking over a tree trunk I stumbled upon a birch growing in sandy soil in a coniferous forest in central Russia.
It looks like over time the tree trunk got bent towards the trail and one of the branches became the new trunk as it now grows straight up, whereas the old trunk is pointing sideways.1
The tree isn't dead, I visited that place during summer time and it was covered with green foliage.
I'm wondering what's the name of such phenomena, how common it is and what usually causes the tree "to change it's mind"?
The following is multiple choice question (with options) to answer.
A tree can be replaced by planting a new what? | [
"tall bush",
"farm",
"grass",
"ford"
] | A | a tree can be replaced by planting a new tree |
OpenBookQA | OpenBookQA-4684 | audio
Title: What are the differences in overtones for hard vs soft materials? I've been researching Physical Modeling lately, and so far pretty much everything makes sense from a physical/logical perspective.
The one thing that I haven't yet found a proper explanation on is the difference in overtones between soft and hard materials. I've seen it mentioned in a few places that this stiffness is the parameter which defines the difference between metallic and nylon string on a guitar, for instance. I've also caught that one of the two directions (hard vs soft) "spreads the harmonics." But that's all I've got.
So, what are these differences in overtones for rigid materials? They seem to be more spread out, I've come to recognize metallic sounds as being rather comb like. But I'm trying to eventually write code to synthesize these sounds, and need to know some details as to the way they are spread.
Also, here's a great video in which most other aspects of physical modeling are pretty well explained, as well as the mention of more spread out overtones for harder materials (though I don't remember at what time): https://www.youtube.com/watch?v=dUcNzPhZdwk I am not sure if this is exactly answering your question but it may help you in your modeling efforts. The metallic strings are going to be fairly simple to model in that the differential equations you use will be only dependent on the shape of string at any given time and the tensile strength of the string.
The nylon strings exhibit non-linear viscoelastic behavior which has a time dependent component to it. That means that is has a memory and the local velocity of the string will be important. By memory I mean there is residual strain built in once plucked and the time for recovery will be much greater than the frequency of motion. I believe this is what gives it a “softer” sound. Classically viscoelastic materials are modeled with a spring and damper in parallel.
Descretizing the string over a number of elements and using a divided differences approach to approximate the differential equations you should be able to get a theoretical sense of how these differences affect the observed signal.
Hope that is helpful for you in thinking about your problem.
The following is multiple choice question (with options) to answer.
Which is likely considered soft? | [
"taffy",
"steel",
"diamond",
"hard pretzels"
] | A | if a mineral can be scratched by a fingernail then that mineral is soft |
OpenBookQA | OpenBookQA-4685 | respiration
Here is what happens at the molecular level.
The $\rm CN^-$ ions diffuse into the mitochondria. They have high affinity to the ferrous ion of the mitochondrial enzyme cytochrome c oxidase involved in the electron transport chain (ETC), one of the phases of cellular respiration where $\rm ATP$ is generated from $\rm NADH$ and $\rm FADH_2$. And it is this process that actually requires oxygen. The inhibited cytochrome c oxidase is of no good in transporting electrons, thus no $\rm ATP$ molecules are generated. The oxygen molecules waiting for those electrons remain empty handed resulting in the increase in the concentration of molecular oxygen. Remember, ETC occurs in almost all living cells except a few like RBC which get their major share of ATP from the highly inefficient anaerobic glycolysis. Also, $\rm ATP$ is the energy currency of our body and is required in a wide variety of bodily processes like osmotic balance, nerve impulse transmission, muscle contraction etc. With no $\rm ATP$ your heart and respiratory muscles can't contract, your medulla can't regulate breathing, your kidneys can't concentrate urine and the list goes on. Death is imminent if a high concentration of cyanide gets into your blood.
The symptoms of panic like tachypnea and tachycardia (that result due to low oxygen in blood) are not usually seen unless the victim himself knows he is poisoned. The end effects like cardiac and respiratory arrest, seizures and coma, however, are similar to those of suffocation.
For further read:
The Mechanism of Cyanide Intoxication and its Antagonism
The following is multiple choice question (with options) to answer.
When a cell takes in in oxygen an use cellular respiration it will then expire | [
"water",
"smoke",
"CO2",
"sunlight"
] | C | In the cellular respiration process carbon dioxide is a waste product |
OpenBookQA | OpenBookQA-4686 | astronomy, telescopes
Title: Fall/Winter Viewing I live in Seattle and am thinking of purchasing a telescope. Is fall/winter a decent time of year for viewing (aside from summer)? Are there any major viewings/events during that this of year?
I know I live in a city of rain, but there are some nice nights. The sky is a constantly changing tapestry of interesting sights and events: there is no time better than any other. If you''re interested, now is the best time!
Because of our location in the Milky Way Galaxy, summer and winter are the best times for viewing objects within the galaxy: open clusters and nebulae. Spring and fall are the best times to view objects outside our galaxy: globular clusters and other galaxies. Because of the Earth's rotation, if you stay up late, you can also get a sampling of the next season. Look at the autumn galaxies this evening, then stay up past midnight to view the winter clusters and nebulae.
Superimposed on the "deep sky" are the solar system objects, which operate on their own clock. Right now, Saturn is disappearing in the west at sunset but Venus will soon replace it; Jupiter rises around 10 p.m. and dominates the rest of the night. Mars is still far away in the morning sky, but is gradually getting closer.
The following is multiple choice question (with options) to answer.
If you were to miss winter how many seasons would you have to wait till you saw it again | [
"4",
"36",
"12",
"1"
] | A | a new season occurs four times per year |
OpenBookQA | OpenBookQA-4687 | 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.
There are 4 seasons a year, meaning a new one | [
"starts every day",
"starts every quarter",
"is fake",
"is seven"
] | B | a new season occurs four times per year |
OpenBookQA | OpenBookQA-4688 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
Which of these live on land as adults? | [
"tiger sharks",
"electric eels",
"fire-bellied toads",
"catfish"
] | C | adult amphibians live on land |
OpenBookQA | OpenBookQA-4689 | infection, amphibians
Title: What is this toad suffering from? Myiasis or chytridiomycosis? I found this toad on Aug. 29th at this location: position on osm
I think it is a bufo bufo, approx. 10 cm long. The nostrils seemed to be completely filled with a grey matter and from the activity of the floor of the mouth it apparently tried to breathe againgst this obstruction. It probably had enough oxygen via its skin though.
I tried to remove the obstruction using a blade of grass but this seemed to produce some pain as the toad closed its eyes on contact, so I stopped. The skin looked fairly normal and the toad was able to walk away after a while.
I can think of two causes for this condition.
Batrachochytrium dendrobatidis infestation
Lucilia bufonivora larvae
I could not see properly, if there were any larvae or unhatched eggs inside the nostrils, but as the rest of the skin seemed unharmed I assume the latter.
Is my assumption valid or is there even a third possibility? It is a female Bufo Bufo and you are right, there are toad fly (Lucilia bufonivora) larvae/eggs inside her nostrills. These flies lay their eggs inside toads' nostrills (specifically on Bufo Bufos) and the larvae start eating them. Sadly this disease ends up by the death of toad. They slowly eat nostrills, then mouth, eyes, and all the head.
Here's a photo of a male bufo bufo, without a head. Someone found it walking around at this situation. https://i.stack.imgur.com/I6twl.jpg
The following is multiple choice question (with options) to answer.
A person with a pet amphibian will likely feed it | [
"deer",
"wax",
"steak",
"meal worms"
] | D | adult amphibians live on land |
OpenBookQA | OpenBookQA-4690 | 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 | [
"are the same as the Southern Hemisphere",
"led to wet fall days",
"correlate to cold months int he Southern Hemisphere",
"correlate to long, sunny days in the Southern Hemisphere"
] | D | December is during the summer in the southern hemisphere |
OpenBookQA | OpenBookQA-4691 | 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.
It is hotter in December than other months. Where are you likely located? | [
"above and beyond",
"above the equator",
"below the belt",
"below the equator"
] | D | December is during the summer in the southern hemisphere |
OpenBookQA | OpenBookQA-4692 | everyday-chemistry, analytical-chemistry, safety, elemental-analysis
Title: How does a mercury detector work? I am new to chemistry and saw a "portable mercury vapor monitor." How do these machines work? There are many ways to detect mercury, and you can find a more detailed analysis of these methods, along with examples of these detectors and their limitations, here.
Gold film sensors
Gold Film Sensors were the first reliable forms of mercury detectors due to gold’s affinity for elemental mercury [...] When a mercury rich air sample passes over a thin gold film, the mercury deposits on the gold and changes the electrical resistance of the foil. This change in resistance is directly proportional to the mass of mercury vapor taken from a known volume of air, which can be calculated in $\mathrm{mg/m^{3}}$.
Cold Vapor Atomic Absorption Spectroscopy (CVAAS)
In mercury CVAAS, a light source of known wavelength and intensity (~254 $\mathrm{nm}$, middle ultraviolet spectrum) is radiated through a sample of air where the light eventually encounters a detector. If mercury is present, electrons from within the mercury atoms will absorb some of this energy from the light source. The difference between the initial energy of the light source and the energy measured by the detector gives you an indirect measurement of how many mercury atoms were initially present.
Atomic Fluorescence Spectroscopy (CVAFS)
Cold Vapor Atomic Fluorescence Spectroscopy (CVAFS) is an improvement upon the traditional CVAAS. When a mercury atom absorbs the energy from the UV wavelength, an electron transitions from a stable ground state to an unstable ‘excited’ state. This excitation event describes atomic absorption as discussed in the [CVAAS] section. However, when the energy source is removed the excited electron returns to its ground state. In doing so, a photon of light is emitted during the loss of potential energy. This fluorescence of light is often unique for various chemical species. Mercury in particular absorbs light at 254 $\mathrm{nm}$ and fluoresces light at the same wavelength. Because the light absorbed and emitted are at the same wavelength, this form of fluorescence is referred to as resonance fluorescence. Other chemicals such as chlorides, sulfides and hydrocarbons absorb light at 254 $\mathrm{nm}$ but either do not fluoresce or fluoresce at a different wavelength.
The following is multiple choice question (with options) to answer.
An active oven will make the mercury in a thermometer go | [
"lower",
"slower",
"upwards",
"brighter"
] | C | temperature is a measure of heat energy |
OpenBookQA | OpenBookQA-4693 | everyday-chemistry, spectroscopy, heat, color
Title: Is it possible to make broad spectrum light absorbing paint? Is there such a paint / pigment that absorbs most wavelengths of light (beyond the visible light range) that can be used for solar heat generating applications? If not, would it be possible to make it? Ideally, this paint would absorb light from the sun in an efficient manner and become heated quickly by solar light. It should probably at least absorb infrared, and any other wavelengths of light that produce significant heat when absorbed. This should be far more effective than normal black paint as black paint only "for sure" absorbs light in the visible spectrum, and this desired paint would absorb other types of light from the sun. Carbon nanotube black is highly absorbent in and outside the visible spectrum, see http://www.extremetech.com/extreme/186229-its-like-staring-into-a-black-hole-worlds-darkest-material-will-be-used-to-make-very-stealthy-aircraft-better-telescopes.
Of course, that does not make it ideal for energy conversion, as it would also need at least the following qualities to be practical.
A good conductor of heat to the heat-exchanger surface below
An enduring finish, resistant to abrasion, heat and environmental degradation
Economical, both in material cost and application
Safety in use and in manufacture
The following is multiple choice question (with options) to answer.
What object would absorb the most solar energy? | [
"white paper",
"mirrors",
"coal",
"water"
] | C | if a substance absorbs solar energy then that substance will increase in temperature |
OpenBookQA | OpenBookQA-4694 | general-relativity, gravity, metric-tensor, curvature, stress-energy-momentum-tensor
You may also solve the Einstein equations numerically. This is e.g. is used to study the black hole collisions where different perturbation theories fail. This is also a situation where the Newtonian theory is useless.
The following is multiple choice question (with options) to answer.
Gravity is an example of which? | [
"Magnetic Force",
"Speed",
"Contact Force",
"Non-Contact Force"
] | D | non-contact forces can affect objects that are not touching |
OpenBookQA | OpenBookQA-4695 | electricity, electrostatics, electric-current
Title: Why does holding an electrical switch in between on and off states cause sparks?
If air is a bad conductor, then why do sparks develop when an
electrical switch is held in between on and off states?
Why are sparks generated when cables carrying heavy electric current
are brought too close? Is it because the electrons are jumping from
the live cable to the other due to the presence of high voltage? The switch really has 2 positions: on and off.
However, when you move the switch very slowly, it may leave the closed position slowly. When the switch is just barely open, the field may cause the air to break down and start conducting, to form a spark (as @anna v explained). To rephrase, the reason why sparks happen is because the switch may only be open a tiny amount, not enough to stop current from flowing through the air. If the gap then increases further, the spark may persist because the air is now acting like a conductor rather than an insulator.
Switches are usually designed to prevent this from happening. They have built-in springs that act to open the contacts quickly and completely, thus preventing sparks. However, with many switches, moving the toggle very slowly may cause the contacts to separate a tiny bit, before they fly completely apart. Older designs are likely to suffer more from this.
Switch design is easier for low-voltage switches, because high voltages are more likely to cause the air to break down and cause a spark. It is the voltage that causes electrons to jump across the gap and create the spark. For that reason, high voltage switches are also larger: they have to be large enough to keep the contacts far enough apart when the switch is open. Remember that high enough voltages can cause electrons to jump between clouds and the ground - that's called lightning.
The following is multiple choice question (with options) to answer.
Which is likely to cause a spark? | [
"ocean sand",
"wet dirt",
"swamp mud",
"loose brush"
] | D | dry wood easily burns |
OpenBookQA | OpenBookQA-4696 | power, estimation, combustion
eg assume 6 kWh/kg for a sample of dry wood.
10% moisture would displace $\rm10\% \times 6000\,Wh = 600\,Wh$ from a 1kg mass.
$\rm600\,Wh = 600 \times 3600 = 2.16\,MJ$.
Energy to heat 100 g water 10$^\circ$C say to
$\rm100\,^\circ C \simeq 4.3\,J/^\circ C/g \times (100\,^\circ C-10\,^\circ C) \times 100\,g \simeq 40\,kJ$.
Energy to vaporise 100g of water from
$100\,^\circ\,\rm C$ to steam = $\rm2260\,J/g\times100\,g = 226\,kJ$
Total energy loss due to vapourising 10% water = $266\,\rm kJ$ = 11%
Loss of energy from water replacing wood = $2160\,\rm kJ$ = 89%.
Total loss to water = $2.426\,\rm MJ$.
Energy loss % in 1 kg wood due to 10% moisture = $\rm2.426\.MJ/21.6\,MJ$ = 11.2%
Not taken into account is the "watergas" process whereby passing water vapour over hot carbon results in breakdown of the water into Hydrogen and Oxygen and re-re action to form CO and CO$_2$. The net energy effects of this process vary immensely with circumstance and are ignored here.
Based on Warm Homes technical report.
The following is multiple choice question (with options) to answer.
dry wood easily what? | [
"scorches",
"freezes",
"evaporates",
"melts"
] | A | dry wood easily burns |
OpenBookQA | OpenBookQA-4697 | neuroscience, action-potential
Title: Fastest and slowest action potential When our instructor asked us about the speed of action potentials in cells, I told him that action potentials and two-wheelers travels at similar speeds. He thought that this is an 'interesting' way of looking at it.
Needless to say after the class I tried to figure out the minimum, average and maximum speed of action potentials in neurons. Wiki helped but its not authoritative. Some place it says that the fastest is 110 m/s and other place it is 120 m/s. While slowest one varies between 7 m/s (in Rana frog) to 0.5 m/s (Nociceptors) on Wiki. The average speed would be hard to calculate.
I am looking for any references where slowest and fasted action potentials are described. They would be interesting cases to write a note for classromm. You can search on Bionumbers.
Here is what I got after searching action potential:
Speed of action potential along non-myelinated invertebrate axons of ~10μm diameter = less than 1 m/s
Action potential speed in myelinated axon = 50 ... 100 m/s
Velocity of action potential in pyramidal tract at 37°C (in Cat Felis) = 164 m/s
It offers you references for every number.
The following is multiple choice question (with options) to answer.
what is the speediest healer? | [
"skin",
"tongue",
"toes",
"heart"
] | B | speed is a measure of how fast an object is moving |
OpenBookQA | OpenBookQA-4698 | thermodynamics, thermal-radiation, physical-chemistry, biophysics, solar-cells
Title: Extreme life - energy source for living tens of kilometers underground? Living cells were found up to at least 12 miles underground (article), and in other extreme places (BBC survey article), for which beside the problem of just surviving in such extreme conditions, a basic physics thermodynamical question is: what energy source it is based on?
And in such extreme temperatures there is needed a lot of energy just to fight 2nd law of thermodynamics - actively protect cell's structures against thermalization.
Such energy source needs to be relatively stable for past billions of years - what seems to exclude chemical energy sources (?)
One stable energy source in such high temperatures are thermal IR photons, and thermophotovoltaics is generally able to harvest energy from them. However, cell living in such extreme conditions would rather have the same temperature, hence 2nd law seem to forbid harvesting energy from such IR photons? Chemical.
As the Wikipedia entry on Lithoautotroph puts it (restricting ourselves to the deep underground forms):
derives energy from reduced compounds of mineral origin
which they do through inorganic oxidation (see, e.g., Lessons from the Genome of a Lithoautotroph: Making Biomass from Almost Nothing) or other reactions, such as the reaction of formate (HCOO-) and water, to form bicarbonate and hydrogen (Extremophile microbes survive only on energy from formate oxidation).
The following is multiple choice question (with options) to answer.
What is the source of energy for life on earth? | [
"rivers",
"planets",
"astral star",
"mountains"
] | C | the sun is the source of energy for life on Earth |
OpenBookQA | OpenBookQA-4699 | thermodynamics, visible-light, perpetual-motion
Needless to say, perpetual motion of an untouched body is useless in terms of extraction of mechanical energy.
The following is multiple choice question (with options) to answer.
Organisms exist only because of the energy from | [
"the moon",
"coffee",
"our yellow dwarf",
"the kardashians"
] | C | the sun is the source of energy for life on Earth |
OpenBookQA | OpenBookQA-4700 | biochemistry, endocrinology, environment
Title: How quickly do estrogens break down in the environment? Of all the synthetic hormones we use, estrogens are probably the most common. They are used for birth control as well as hormone replacement therapy. This researcher also shows that there is plenty of it in milk because dairy cows are often pregnant while they are being milked.
Estrogen is a sturdy compound, very much like cholesterol. I was wondering if anyone had any idea how long it would survive in the environment, given that some people are concerned about it interrupting animals life cycles. How fast does it break down in the wild? Months to years - although the actual duration in a specific environment depends on the nature of that environment and is tied to oxygen level. Higher oxygen, faster degradation. Less oxygen, the estrogen molecules interconvert among various closely related molecules which hampers both their detection and their degradation.
For more info, please see: Environmental science: The hidden costs of flexible fertility (Nature 485, 441 (24 May 2012)) and this Science Daily article.
The following is multiple choice question (with options) to answer.
What environment is often green? | [
"tree zones",
"arctics",
"deserts",
"oceans"
] | A | a forest environment is often green in color |
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