source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-1401 | The first trial that gives the most information is to do four vs. four (ABCD vs. EFGH). No matter what the result we have reduced the possible solutions from 24 to 8.
Possibilities Test Result Possibilities
A lighter
A heavier
B lighter
B heavier
C lighter
C heavier
D lighter
D heavier
E lighter
E heavier
F lighter
F heavier
G lighter
G heavier
H lighter
H heavier
I lighter
I heavier
J lighter
J heavier
K lighter
K heavier
L lighter
L heavier
ABCD vs. EFGH = I lighter
I heavier
J lighter
J heavier
K lighter
K heavier
L lighter
L heavier
< A lighter
B lighter
C lighter
D lighter
E heavier
F heavier
G heavier
H heavier
> A heavier
B heavier
C heavier
D heavier
E lighter
F lighter
G lighter
H lighter
• If the seesaw is equal then we know those eight islanders (ABCDEFGH) can be eliminated from being either lighter or heavier. The remaining four islanders (IJKL) could then be either lighter or heavier.
• If the seesaw is unbalanced then we know the four untested islanders (IJKL) can be eliminated. We also know that all the islanders on the heavier side cannot be lighter. And all the islanders on the lighter side cannot be heavier.
What we do for the second trial depends on the type of result for the first trial because the pattern of remaining possibilities is different.
• If the first trial was balanced then we have four remaining islanders (IJKL) that could be either lighter or heavier. We can work out the remaining possibilities by comparing three remaining islanders (IJK) with three normal islanders (ABC).
The following is multiple choice question (with options) to answer.
In a contest to see which would win based on size and weight, the winner with more of both would be | [
"moon",
"Earth",
"pebble",
"cat"
] | B | the earth has more mass than the moon |
OpenBookQA | OpenBookQA-1402 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
A renewable resource you can find on Earth is | [
"stars",
"Oil",
"sand clay",
"fossil fuels"
] | C | a renewable resource can be replaced |
OpenBookQA | OpenBookQA-1403 | spherical-astronomy
This next chart shows the results of the calculations for the same time period:blue trace and left axis for the longitude of the ascending node and red trace, right axis for orbital obliquity.
The chart doesn't show anything that's actually happening on any pair of days, just the results of calculations made from observations at the time. The longitude result trace shows the ongoing estimate of the ecliptic longitude at the last passing of the ascending node. The latitude trace shows the ongoing estimate its peak value from the preceding to the following upward crossings of the ecliptic.
The actual two upward crossings:
May 17, day 15, 34.05 degrees;
June 14, day 43, 33.06 degrees. The actual negative peak of the ecliptic latitude -5.2344 gegrees, positive peak 5.2038.
The following is multiple choice question (with options) to answer.
Shortly after the moon is in ecliptical longitude with the Sun, one will see | [
"a waning crescent",
"a waxing crescent",
"a waning gibbous",
"a waxing gibbous"
] | B | the first quarter phase of the moon occurs after the new moon |
OpenBookQA | OpenBookQA-1404 | newtonian-gravity, free-fall, weight
Title: No water from hole of the cup because of weightlessness? Let's say I have cup with water, but with a little hole in the bottom of cup somewhere
Galileo worked out that if you just let something fall, it will accelerate towards the ground at the same rate whatever it is.
Above seems to be the reason why the water doesn't come out from the water during the free fall because both the water and cup will accelerate towards the earth at the same speed.
Can some explain me the above phenomena in the sense of weightlessness? When in free fall, the water and the cup both experience the same acceleration. Therefore, they both move together. Therefore, there is no "force" that wants to separate the water from the cup.
how weightlessness comes into the picture?
OK, forget the cup and forget the water. Let's consider a bathroom scale instead.
When you stand on a bathroom scale it measures your "weight". That is, it measures the force between the soles of your feet and the ground. Your body wants to "freely fall" toward the center of the Earth, but the ground gets in the way: The ground pushes up on your feet exactly as hard as is necessary to stop you from falling, and the scale measures that force.
Here's what happens if we move both you and the scale to the International Space Station. Your body doesn't just want to freely fall toward the center of the Earth, it actually does freely fall. And, the scale also freely falls, and the space station surrounding you also freely falls. There's nothing up there to push up on your feet to stop you from falling because everything is falling together. Even if your feet are touching the scale, and the scale is touching the wall, there's no force acting because there's nothing that gets in the way of anything else falling.
Weight is force. No force is no weight... Weightlessness.
The following is multiple choice question (with options) to answer.
A person in space will find a lack of something to drink if they land on | [
"Mars",
"the earth",
"the moon",
"third planet"
] | C | the moon does not contain water |
OpenBookQA | OpenBookQA-1405 | evolution, botany, photosynthesis, speculative, chloroplasts
Title: Why do plants have green leaves and not red? I know plants are green due to chlorophyll.
Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light has more energy than red light.
Is there no alternative to chlorophyll? Or is it something else? Surely it would be even more beneficial for plants to be black instead of red or green, from an energy absorption point of view. And Solar cells are indeed pretty dark.
But, as Rory indicated, higher energy photons will only produce heat. This is because the chemical reactions powered by photosynthesis require only a certain amount of energy, and any excessive amount delivered by higher-energy photons cannot be simply used for another reaction1 but will yield heat. I don't know how much trouble that actually causes, but there is another point:
As explained, what determines the efficiency of solar energy conversion is not the energy per photon, but the amount of photons available. So you should take a look at the sunlight spectrum:
The following is multiple choice question (with options) to answer.
Chlorophyll is good for allowing plants to absorb energy and | [
"is dry",
"is dead",
"is clear",
"is healthy"
] | D | chlorophyll is used for absorbing light energy by plants |
OpenBookQA | OpenBookQA-1406 | human-biology, neuroscience, brain, endocrinology, sleep
Title: Is it possible for a human to wake up in a wrong way? There's an old folk saying that goes like "He got out of bed on a wrong foot" - to indicate that the person's day is going poorly because of the way that person woke up.
Is it is possible for a human to disrupt the awakening process, causing negative cognitive side effects for the rest of the day? If so, how long does it take to restore normal cognition?
There's this related question that I asked - if different parts of a human brain can be asleep independently of each other? This question is a variation on that one, and specifically deals with the process of awakening or activating brain regions in the morning.
I'm aware of the concept of "Sleep inertia". However, it does not seem to be the phenomenon in question, as sleep inertia is frequently mentioned in the context of napping. (where napping over a certain time leads to sleep inertia). Additionally, sleep inertia has been described in terms of decline of motor activity, and not as cognitive side effects lasting for a whole day.
From personal experience, it seems that I'm doing best if I get out of bed immediately following a natural awakening, even if it is rather early, as opposed to snoozing for another 30-40 minutes. I did a quick search and found some research in this area. Sleep inertia is the technical term for feeling groggy for a while after waking up.
In a review article by Patricia Tassi, Alain Muzet (Sleep inertia. Sleep Medicine Reviews. Volume 4, Issue 4, August 2000, Pages 341–353), they define sleep inertia as
Sleep inertia is a transitional state of lowered arousal occurring immediately after awakening from sleep and producing a temporary decrement in subsequent performance.
and also says,
Depending on the studies, it [sleep inertia] can last from 1 min to 4 h. However, in the absence of major sleep deprivation, the duration of sleep inertia rarely exceeds 30 min.
Same article reviews several studies (first report in 1964) on sleep inertia relating to sleep stages:
Abrupt awakening during a slow wave sleep (SWS) episode produces more sleep inertia than awakening in stage 1 or 2, REM sleep being intermediate.
The following is multiple choice question (with options) to answer.
A man is at the beach and is napping in the sun. He falls into a deep sleep and forgets to wake up. After hours of this, he | [
"may flood beaches",
"may make whiskey",
"may cease existence",
"may file lawsuit"
] | C | if an organism becomes too hot then that organism may die |
OpenBookQA | OpenBookQA-1407 | ros
i7-7700k
16GB RAM
GTX 1050 Ti graphics card
H170 chipset motherboard
120 GB SSD
For Gazebo, you want a CPU with a high single core frequency, rather than many cores (ie, choose i7 over a server type CPU with 16 cores at 2.2GHz). Using htop to see resource usage, it seems that Gazebo server has two main threads that consume decent CPU resources, and Gazebo client has one main thread. There are then a few other threads that consume small amounts of CPU. The i7 runs great and Gazebo is always above 0.98 realtime, even in large environments (see below).
For RAM, the only real benefit to adding more is if you are going to simulate huge areas and create large maps using many different sensor streams. When running a 100mx100m Gazebo world, with 30+ tree models, a 3D camera (depth image and point clouds) and 2D laser scanner, 100mx100m Octomap and multi-layer Grid Maps at 0.1m resolution, my RAM usage is about 5GB.
A graphics card makes very little difference for Gazebo since it isn't exactly graphics-intensive. The model above uses about 200MB of graphics memory and the card is only running at about 35% capacity. You could likely even skip the graphics card altogether and use the onboard graphics just fine.
My 120GB SSD size is ok for simulation, but if you want to save large bagfiles of sensor (point cloud or image) data, I'd go for something larger, or pair it with a cheap+large spinning disk HDD. We generate bagfiles from our actual machine that produce about 30GB of sensor data per minute! But I'm sure you won't have this requirement.
We have another office PC that has an i5 CPU and GTX 1060 and it struggles to run Gazebo server and client simultaneously. I'd suggest getting the best CPU you can afford and splitting the rest of the money across the other, less-critical components.
Originally posted by ufr3c_tjc with karma: 885 on 2017-12-10
This answer was ACCEPTED on the original site
Post score: 3
The following is multiple choice question (with options) to answer.
A computer needs what to be functional | [
"money",
"positive ions",
"a mommy",
"youtube"
] | B | electric devices require electrical energy to function |
OpenBookQA | OpenBookQA-1408 | civil-engineering, architecture, cooling
Title: How are passive houses made in very hot regions (like Saudi Arabia)? I think, here is the main problem the difference between the internal and the external temperature.
For example, in Saudi Arabia, in 50 C, a passive house needed probably much sophisticated planning as in Paris.
Compared to the traditional cooling systems, in the second case is enough only to get a cooling system with bigger power. I think, they are much more scalable.
Is it anyways possible? A yahkchal is an example of a type of passively cooled building in Iran
They utilise a combination of passive evaporative cooling and thick thermally insulating walls in order to keep the interior temperatures low enough.
First, wind is directed into underground aquifers known as qanat. They are then cooled due to the low humidity desert air causing water to evaporate. The cooled air then flows through the interior of the yakhchal, cooling the interior.
The thick insulating walls (filled with earth and various insulating materials such as straw and feathers) help to insulate the cool interior from the hot exterior, therefore maintaining a low temperature inside the yakhchal.
The following is multiple choice question (with options) to answer.
Places lacking warmth have few what | [
"biological entities",
"biological weapons",
"cold entities",
"astronomical entities"
] | A | cold environments contain few organisms |
OpenBookQA | OpenBookQA-1409 | astronomy, everyday-life, popular-science, climate-science
It is for much the same reason that Winter is colder than Autumn, even though they have the same amount of daylight hours.
The following is multiple choice question (with options) to answer.
Several animals flourish in cold temperatures like | [
"Lizards",
"Terns",
"Antelope",
"Kangaroos"
] | B | cold environments contain few organisms |
OpenBookQA | OpenBookQA-1410 | rotation, habitable-zone, weather, astrobiology
One of the interesting historical facts of life on Earth, at least to me, is how long it took what we might consider advanced life to develop. One celled life in various forms was around for over 3 billion years but the first fossils are about 650 million years old. It took life a very long time on earth to get from too small to see to large enough to leave a footprint . . . but, I digress.
I agree 100%, one celled life or Tardegrades could live on a planet with no tilt or 90 degree tilt. Easy. Ocean life in general should be fine cause oceans are more adaptive. Evaporation keeps ocean surfaces colder than land gets during peak heat and while a completely frozen over ocean isn't great for life, cold oceans hold more oxygen and CO2 which can be good for life. Oceans also circulate as an effective means of temperature moderation and fish don't really care how windy it is or how much or little it rains. The tilt question, I think, is really just about life on land.
Land life could be more vulnerable to high wind, extreme temperature shifts, droughts or floods, which could be driven by greater axial tilt, but I find it hard to believe that Axial Tilt is the be-all and end all. Day length and year length are key factors too.
One point I agree with the article on, is that a close to 90 degree tilt might not be ideal with one part of the planet always facing the sun and the other part never facing it but outside of extreme tilts, I don't see why it would be a big deal.
A thick cloud cover, for example, reduces seasonal changes. There's a number of factors.
The following is multiple choice question (with options) to answer.
If an environment experiences harsh climates | [
"plants will continue to flourish",
"ponds may dry up",
"tadpoles will mature faster into frogs",
"animals will experience a boom in reproduction"
] | B | a greenhouse is used to protect plants by keeping them warm |
OpenBookQA | OpenBookQA-1411 | rivers, geomorphology
Title: Is initial stream formation in a drainage basin random? It's known that stream orders are highly regular:
Horton showed that stream order is related to number of streams, channel length, and drainage area by simple geometric relationships; that is, stream order plots against these variables as straight lines on semilogarithmic paper.
[...] Among many samples of basins in the United States the bifurcation ratio tends closely to equal 3.5. There are variations, of course. In the examples of basins cited by Horton (1945, p. 290) values of the bifurcation ratio range from 2 to 4.
Fluvial Geomorphology, p.137
The stream bifurcation ratio is so regular in any given drainage basin that it's actually remarkable to look at a graph - as in these Indian continent sub-basins.
The process Fluvial Geomorphology describes for the evolution of these basins involves the random weathering of locally-level surfaces by rain, melt, or less commonly other liquid weathering. Small rivulets form via random depressions in the surface of the earth, which then merge into larger streams of higher order. But this got me thinking...
If the emergence of initial rivulets is a random process, shouldn't that random process be biased towards wherever the drainage basin happens to be the most erodible? I'd only expect this kind of macro-level structure to necessarily emerge if the earth were homogeneous in the drainage basin, but in practice this doesn't seem to need to be required in order for a drainage basin following a regular bifurcation ratio to emerge.
My questions are related:
The following is multiple choice question (with options) to answer.
A small creek becomes a rushing river after years of heavy rains in a particular location. In addition to the larger water source, there are also greater | [
"rock fights",
"sheep herds",
"bunny rolls",
"speaking deer"
] | B | as the available water in an environment increases , the populations of organisms in that environment will increase |
OpenBookQA | OpenBookQA-1412 | An example of an "unjustified step" occurred famously in Andrew Wiles's first announcement that he had proved Fermat's Last Theorem. Someone (actually, I think multiple people) found a mistake in the proof he presented. After he made a considerable additional effort, he was finally able to present a proof without that mistake, and this proof was accepted.
Some comments under the original question raised the issue of how we check the intermediate steps of a proof by contradiction, claiming that it is easier to check the steps in a direct proof since their conclusions are all true.
Things that we want to prove typically have the form $S\implies T,$ for which a direct proof typically involves assuming $S$ and then showing that $T$ follows. In the intermediate steps of the proof, we have some facts that depend on $S,$ which we cannot "check" by simply observing that they are true; we can check them by verifying the logic in every step leading up to that part of the proof, or we can check them by coming up with an alternative proof showing that they follow from $S.$
We may also introduce some known facts (which do not depend on $S$) in the course of the proof, which we can check simply by verifying that they are true facts.
A third possibility is that we derive something from $S$ that we could have known to be true without assuming $S.$ This is wasteful; we could improve the proof by simply introducing these facts as known without showing a logical derivation from $S.$
The same things happen in proof by contradiction. We will have some steps that we can check only by checking every step in the logic leading up to them or by devising an alternative proof, we may have known facts that we can check more easily, and we may even have wasted effort by deriving something from our (false) assumption that we could have simply brought in as a known fact.
The following is multiple choice question (with options) to answer.
Knowing what to do without ever being taught is known as | [
"learned",
"found",
"instinctive",
"given"
] | C | an animal knows how to do instinctive behaviors when it is born |
OpenBookQA | OpenBookQA-1413 | time, navigation
Help me get my character back to 1962...in time to get involved in the Cuban Missile Crisis!
Edit To Add: It's been autosuggested that I edit my question. What I'm looking for are patterns in the night sky which might predictably change over long periods and which a physicist knowledgeable of astronomy could recognize and interpret. Aside from the Mark V sextant (which does have an internal, radium-illuminated bubble level/horizon), what other tools, instruments, and reference works would be helpful? Again, I'm not suggesting that he focus down to a specific day or even year; if he can chronologically locate himself within a twenty- or even fifty-year window it will work for the purposes of my story.
Second edit: It has been suggested that an observation of Uranus and Neptune would be helpful. I'm pretty sure that Neptune is out, but the Mark V sextant has a 2x telescopic optical path. Is it possible to take an accurate sighting of Uranus with a 2 power telescopic sextant after you have located the position of the planet with a larger, portable tripod-mounted telescope? If so, or if an sufficiently accurate sighting could be taken with the larger telescope, how would one work out the calculations from there? Your semi-intuitive thought that there must be a pattern of the planet locations that would show the date is correct, I think. You won't need any special equipment but a sextant which will measure angles between stars and planets - can't be a bubble sextant. You will also need data:
(1) The sidereal hour angles (SHAs) of
Jupiter and Saturn on your departure day or any day within a few weeks
of it.
(2) Eccentricity, aphelion, perihelion, semi-major axis, and date of the
perihelion closest to the departure day for both planets and Earth.
Siderial orbit period for Jupiter and Saturn.
(3) Trig tables.
(4) Navigational star chart.
At the time the plane lands Jupiter and Saturn will have traveled some
number of complete orbits around the sun and a partial orbit. The number of
complete orbits will be different for the two planets, as will the sizes of
their two partial orbits.
The first task is to find Jupiter and Saturn. They're bright and their
The following is multiple choice question (with options) to answer.
An observer on Jupiter would encounter localized periods of | [
"darkness and light",
"constant nuclear fission",
"supernovas",
"black holes"
] | A | a planet rotating causes cycles of day and night on that planet |
OpenBookQA | OpenBookQA-1414 | 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.
when the needle of a compass lines up with Earth 's magnetic poles , the needle is | [
"pointing east",
"pointing west",
"pointing at arctic",
"pointing to space"
] | C | when the needle of a compass lines up with Earth 's magnetic poles , the needle points north |
OpenBookQA | OpenBookQA-1415 | zoology
Title: Are penguins plantigrade or digigrade? I'm trying to rig a 3D model of a penguin, but I don't know where to put the bones near the ankle because I can't tell if they're digigrade or plantigrade. Nearly all birds are digigrade, but penguins spend a lot of time walking and don't generally grasp or run with their talons. Plantigrade.
The penguins are highly specialized for their flightless aquatic
existence. The feet are located much farther back than those of other
birds, with the result that the bird carries itself mostly upright;
its walk can thus be described as plantigrade (i.e., on the soles).
The sole comprises the whole foot instead of just the toes, as in
other birds. The most notable characteristic of the group is the
transformation of the forelimb into a paddle. This is accompanied by a
body morphology particularly adapted to movement in a liquid medium.
The thoracic (rib) cage is well developed, and the sternum bears a
pronounced keel for the attachment of the pectoral muscles, which move
the flippers. The flipper has the same skeletal base as the wing of
flying birds but with its elements shortened and flattened, producing
a relatively rigid limb covered with very short feathers—an ideal
organ for rapid propulsion. The body plumage likewise consists of very
short feathers, which minimize friction and turbulence. The density of
the plumage and the layer of air that it retains provide almost
complete insulation of the body.
https://www.britannica.com/animal/penguin#ref3467
The following is multiple choice question (with options) to answer.
A penguin, while a bird, would avoid living in | [
"a cold pole",
"a zoo",
"a frozen habitat",
"a native forest"
] | D | some birds live in forests |
OpenBookQA | OpenBookQA-1416 | reflection
Title: Why the transmitted pulse in pulse-echo technique cannot be too long? Question. An ultrasound pulse-echo technique is used to produce an image by reflection from many boundaries. If the transmitted pulse is too long, the image produced is of poor quality. Why?
My attempt. If the transmitted pulse is too long, then the pulse contains many wavelengths. After that, I would receive pulses containing the same number of wavelengths but with lower intensity. Then I am stuck. I even wonder why the transmitted pulse cannot be replace by continuous ultrasound so that we could have continuous reflected image. Any kind of help would be appreciated! This has more to do with signal processing than physics per se. A pulse is usually a chirp, i.e. an increasing or decreasing frequency signal. You could dilate it but if you keep all subbands active all the time then you have no way to determine a start or a end to the band signal so no way to calculate delays either. Delays are what is used to compute distances using this type of imaging. The longer the sound takes to feed back the sampler, the farther the target is assumed to be located. So you need a way to precisely determine the timing of what comes in and back. Also some frequencies can be absorbed by the material so the pulse is designed to send a wide range of frequencies at once. But it has to be short so you know what pulse number you are going to listen to next. Optimizations can be made so as to send multiple pulses before the first comes back, it just gets more complicated to make sure which is which.
The following is multiple choice question (with options) to answer.
Echo is when sound reflects off of what? | [
"atmosphere",
"tables",
"surface winds",
"sunlight"
] | B | echo is when sound reflects off of a surface |
OpenBookQA | OpenBookQA-1417 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
In order to see water evaporate you could | [
"make pasta",
"clean the windows",
"drink water",
"dry your hair"
] | A | evaporation is a stage in the water cycle process |
OpenBookQA | OpenBookQA-1418 | ros, ros-kinetic, cram
Originally posted by mgao on ROS Answers with karma: 1 on 2019-04-20
Post score: 0
Hi,
The object centered view is generated for the cases when the object is completely not in camera view or only a part of it is visible. That is, the object is not occluded by other object but the robot is not looking at the object at all, it's not in the view. In that case the number of visible pixels of the object will be 0. Please refer to chapter "3.1.2 Visibility Computation" on page 126 (142) of @Lorenz's thesis for in detail explanations:
https://mediatum.ub.tum.de/doc/1239461/1239461.pdf
Originally posted by gaya with karma: 311 on 2019-04-23
This answer was ACCEPTED on the original site
Post score: 0
The following is multiple choice question (with options) to answer.
If an object is close then how will that object appear? | [
"gigantic",
"minute",
"small",
"tiny"
] | A | if an object is close then that object will appear large |
OpenBookQA | OpenBookQA-1419 | design, hydraulics
Title: possibility for hydraulic accumulator with no moving parts? Some background for context only
I am in the process of designing a pressure system where my pressurized fluid needs to be kept incredibly clean, with typical contaminants at the ppt or below level. The fluid in question is more compressible than a typical hydraulic fluid, so I need to build in an expansion volume for when I cycle to lower pressure. This expansion volume is going to look very much like a hydraulic accumulator.
The most common hydraulic accumulators are pneumatic, and the gas charge is separated from the fluid by a bladder, diaphragm, piston, or metal bellows. All of these are problems for my cleanliness requirements, as the moving parts will tend to shed metal shavings, etc.
The question
My question is, why is the separation of the two volumes necessary? In my case, this is for a fixed piece of equipment, so I can guarantee that the accumulator will always be vertical. Can I just have a nitrogen-filled cylinder with the fluid connected at the bottom and rely on the fluid to act as my piston? If this does work, why isn't it more common?
Edit to address some of the comments:
I'm not asking for advice on how to design a clean accumulator; I only want to know the fairly general question of whether it is possible to not separate the charge gas from the fluid. gases are soluble in oils. this means that as your oil enters the gas-filled accumulator and the pressure in it builds up, gas will probably dissolve into the oil. Then, when you release the pressure on the system, the gas will boil out of solution and cause the oil to foam up vigorously. the foamy oil then enters your plumbing and creates big problems, especially if it is ingested by a pump.
The following is multiple choice question (with options) to answer.
Leaving remain oil supplies alone is a form of | [
"conservation",
"deliberation",
"transportation",
"pollution"
] | A | An example of conservation is not using fossil fuel |
OpenBookQA | OpenBookQA-1420 | mechanical-engineering, gears
Title: Looking for a gear similar to bicycle freewheel I have an engineering application where I would like to use a single 24v DC Stepping Motor to power two different axles of opposing direction. Basically when the motor turns clockwise, Axel A will spin and Axel B will be stationary. When the motor turns counter-clockwise, Axel A will be stationary and Axel B will spin.
I need it to be as cheap and simple as possible. So far, the best solution that I could come up with to accomplish this is by using two gears similar to the bicycle Freewheel / Freehub. The problem is, I cannot for the life of me find a gear that is similar to that application, but for uses outside of bicycles (possibly because I don't know that specific gear's name). Can anyone recommend a gear or something that is similar to the application that I need?
I have a general idea of the function that I need, but I don't know the name of this type of ratcheting gear. You can get one way bearings which rotate freely on one direction and lock in the other.
So if you use one to attach a gear or pulley to your motor output shaft then the pulley will be coupled to the shaft in one direction and not in the other so with two mounted in opposite orientation each with a pulley driving a separate shaft (A and B) you should be able to achieve what you want.
The following is multiple choice question (with options) to answer.
A bicycle may be used for | [
"rain",
"cats",
"coffee grinding",
"elephants"
] | C | a bicycle contains screws |
OpenBookQA | OpenBookQA-1421 | equinox
Title: Understanding date of astronomical events I have a masters in chemistry but pretty much, a layman in astronomy.
So, can you please explain to a novice like me, about this paragraph taken from the Wikipedia article on Makar Sankranti:
There are two different systems to calculate the Makara Sankranti date: nirayana (without adjusting for precession of equinoxes, tropical) and sayana (with adjustment, sidereal). The January 14 date is based on the nirayana system, while the sayana system typically computes to about December 23, per most Siddhanta texts for Hindu calendars.
Am I correct to understand that when the date was assigned in Hinduism some thousand (?) years back, the winter solistice used to be on 14th/15th January? Precession of equinoxes means that the North pole of the Earth is changing its direction. This also means, that the dates of the seasons (seen from outside the Solar System (= sidereal)) are changing. Nirayana calculates the date of Makar Sankranti with adding years to the first Makar Sankranti, but sayana calculates the date of Makar Sankranti relative to stars (sidereal).
In a nutshell: nirayana is on the same date as the first event (first Makar Sankranti), but sayana is on the same event as the first Makar Sankranti (winter solstice). Yes, winter solstice was once on the 14 January.
The following is multiple choice question (with options) to answer.
A person may celebrate an equinox | [
"biyearly",
"monthly",
"yearly",
"biannually"
] | D | an equinox occurs twice per year |
OpenBookQA | OpenBookQA-1422 | the beginning of the 4 year period". then it would have been difficult to solve. Thanks Say the number of trees at the beginning of the 4 year period was x, then: At the end of the 1st year the number of trees would be $$x+\frac{1}{4}x=\frac{5}{4}*x$$; At the end of the 2nd year the number of trees would be $$(\frac{5}{4})^2*x$$; At the end of the 3rd year the number of trees would be $$(\frac{5}{4})^3*x$$; At the end of the 4th year the number of trees would be $$(\frac{5}{4})^4*x$$; At the end of the $$n_{th}$$ year the number of trees would be $$(\frac{5}{4})^n*x$$; So, we have that $$(\frac{5}{4})^4*x=6,250$$ --> $$\frac{5^4}{4^4}*x=5^4*10$$ --> $$x=4^4*10=2,560$$. Answer: D. If the question were "if all of the trees thrived and there were 6250 trees in the orchard at the end of 15 year period, how many trees were in the orchard at the beginning of the 4 year period", then we would have that: $$(\frac{5}{4})^{15}*x=6,250$$ --> $$x\neq{integer}$$, so it would be a flawed question. Hope it's clear. Isn't the question quite ambiguous, though? I mean the first scentence could be interpreted as "for the first year we have (4/4)x and for the second year (5/4)x and for the third..." etc.. With that reasoning one would have (5/4)^3 * x + x and then your approach doesnt work. Obviously, I understand that this was a flaw in my reasoning but I cannot understand
The following is multiple choice question (with options) to answer.
A person cuts down their neighbor's tree without permission. The neighbor who lost the tree is upset, and sues for the cost of the tree, which depends on the age of the tree at the time of cutting. The tree age is determined by | [
"size of branches",
"number of leaves",
"color of roots",
"number of circles"
] | D | a tree growing a tree-growth ring occurs once per year |
OpenBookQA | OpenBookQA-1423 | meteorology, atmosphere, carbon, co2, rain
Bear in mind that this assumes an enormous rainfall intensity, 100% CO2 saturation of the water and equilibrium chemical dynamics. After the raindrops hit the ground at least half of it will immediately re-evaporate back into the air, leaving, at absolute most, about 3% of the atmospheric CO2 leached out of the atmosphere that will be available to react with the soil, rock or biosphere. Also consider that this is but one of several important processes affecting CO2 transience, such as photosynthesis, respiration, volcanism, industrial pollution, etc. So the CO2 estimates that you read about are average values. Advection and turbulent air mixing should ensure that the CO2 regains approximately normal concentration within an hour or two after rainfall.
The following is multiple choice question (with options) to answer.
What decreases in an environment as the amount of rain increases? | [
"solar light",
"water",
"rivers",
"hydration"
] | A | as the amount of rain increases in an environment , available sunlight will decrease in that environment |
OpenBookQA | OpenBookQA-1424 | waves, atmospheric-science, turbulence
The clouds form if the rising air reaches the lifted condensation level before the updrafts are stopped by an inversion or stable layer. The air is (relatively) clear above the downdrafts. If the convection rolls were perfectly circular, the cloud row spacing would be twice the height of the inversion/stable layer.
Mathematically, there are many wavelength solutions to convection, but the wavelength that dominates is the fastest growing one. In the Boussinesq approximation, which is reasonably valid here, this turns out to have a wavelength of $2\sqrt{2}\sim 3$ times the height of the convecting layer, i.e. slightly flattened. (See, for example, Eq. 21 of Kuettner (1971) "Cloud bands in the earth's atmosphere: Observations and Theory".)
For typical cumulus cloud heights of $\sim 2$ km, we expect typical spacings of about $6$ km.
Wave, lee, or mountain clouds are lines of clouds downwind of an obstacle (such as a mountain range). The lines are parallel to the wind direction. These are buoyancy waves where wind pushes denser air over an obstacle (e.g. a mountain range) and it ends up above less dense air on the other side. This dense air starts to fall but it overshoots into even higher density air at lower altitude, which forces it back up, and the air ends up bouncing up and down until the oscillations die out. If the vertical temperature profile of the air then is known, it is possible to estimate the vertical buoyancy angular frequency
$$N=\sqrt{\frac{g}{\theta}\frac{d\theta}{dz}}$$
The following is multiple choice question (with options) to answer.
The pressure in air drops very low, so clouds | [
"flood",
"sink",
"precipitate",
"melt"
] | C | as air pressure decreases , the chance of rain will increase |
OpenBookQA | OpenBookQA-1425 | It just turns out nicely for C that he is one of the people whose hat colors D and C both know about.
To introduce a modified challange: if the task were to yell out C's hat color right away, D would know for certain, C would have the increased probability of $2/3$ and A and B would be stuck with the random guess of $1/2$. D still knows more.
The following is multiple choice question (with options) to answer.
People can touch something to see if it's | [
"shiny",
"red",
"striped",
"wrinkled"
] | D | touch can be used for detecting texture |
OpenBookQA | OpenBookQA-1426 | thermodynamics, energy, earth, thermal-radiation
@Benjohn has given you the correct answer. Here is my take.
The ultimate heat provider of the earth ( except a small percentage of heat from the magma at the center of the earth) is the sun. It pours down at the surface about 1.2 kilowatts of energy per meter square ( which btw is directly used by solar panels). The same energy falls on the surface of the moon whose surface burns up during its daytime and freezes by black body radiation at night.
The earth is fortunate to have a gas atmosphere which mitigates the extremes of the possible temperatures that the ground would reach otherwise. An example of mitigation is what happens at the sea floor. Most of the energy is picked up by the water and the floor is kept at a steady temperature with small changes day and night in the first meters from the surface, depending on the season, radiating away with the black body radiation, but the body of water has such large heat capacity that variations are small.
The gas atmosphere is a more temperamental "blanket", its heat capacity depends on several gases , called green house gases from the bad impression that agricultural green houses work that way ( they do not, they work by inhibiting heat exchange by convection but that is another story, on which there is no controversy).
The main green house gas is water , H2O. It is worth contemplating this figure :
Solar irradiance spectrum above atmosphere and at surface. Extreme UV and X-rays are produced (at left of wavelength range shown) but comprise very small amounts of the Sun's total output power.
We see that H2O has the most absorption spectrum for infrared wavelengths, (which are the wavelengths of heat )and then comes CO2. Green house gases absorb both incoming and reflected from the surface of the earth infrared, and as most of the reflected wavelengths are in the infrared they act as a slowing down of the black body radiation that would finally leave the earth. As a blanket keeps a person warmer green house gases by playing ball with infrared radiation ( the wavelengths where heat is really transferred) keep the surface of the earth into a reasonable temperature for life, lucky us.
The following is multiple choice question (with options) to answer.
The Earth's primary source of both light and heat is | [
"jupiter",
"the moon",
"a yellow dewarf",
"titan"
] | C | the Sun is the star that is closest to Earth |
OpenBookQA | OpenBookQA-1427 | thermodynamics, atoms, phase-transition
But let's look at how the states change. In a solid, you have a bunch of atoms that can be thought of as masses connected by springs. As heat is added to the system, the atoms begin to vibrate in the lattice of springs. As more heat is added, they vibrate enough to break the springs. This is when the solid begins to melt and turn to a liquid.
Now you have a liquid where the atoms are all moving around but they aren't free to move wherever they want. More heat is added to the system and the atoms begin to translate faster and faster. Eventually they translate fast enough to overcome the forces that are holding them together in a liquid. Now they fly free and are a gas.
So ultimately, heat is energy that makes atoms and molecules move in some way. They may translate, rotate, vibrate, or the electrons may begin moving around depending on how much heat is there and what configuration the molecule has.
The following is multiple choice question (with options) to answer.
The level of atom activity where it reaches a moment where the solid state becomes more loose overall is referred to? | [
"smoothness",
"water fluid",
"liquidity",
"fluid transport"
] | C | heat can change the state of matter |
OpenBookQA | OpenBookQA-1428 | newtonian-mechanics, waves, earthquake
The group of curves inside the envelope but outside (2)
As the quake starts to show up, the pendulum notes down every fractional increase of the it's magnitude. And so, the inclination of the ellipses totally curve out (perpendicularly) thereby forming new ellipses at right angles to the previous ones. Now you might ask me a question...
Why are the perpendicular ellipses confined to a small region and do not spread out?
As you can see in the image, each and every fringe in the larger ellipses are equidistant (somewhat) from each other. As the magnitude increases, the fringes begin to compress which could be noticed in the small ellipses. This shows that the quakes weren't too smooth. As the pendulum starts the ellipse, the quake forces it to wiggle in the exactly opposite direction. For this reason,
The group of intertwined curves at the center
This is very very simple than the others. The earthquake has increased to its utmost magnitude. Now, the ground has shaken in every direction which has confused the pendulum to oscillate everywhere. Luckily, it has also made a rose by its random twist & twirl...
The following is multiple choice question (with options) to answer.
When certain things are shoved together enough, the earth will tremble and shake because of these | [
"trail and error",
"water road",
"dirt collisions",
"wet trail"
] | C | tectonic plates being pushed together causes earthquakes |
OpenBookQA | OpenBookQA-1429 | navigation, mapping, rviz
I can see the grid (of course).
I can see black lines which match the walls that my Kinect can see. These match the documentation on the wiki at /rviz/DisplayTypes/Map) as being cells that are occupied. So far this makes sense.
But I can also see a greyish green transparent horizontal bar that is about 1.5 grid cells tall, whose lower left corner is at (-1, -1) and which extends to the right off the grid. What is this?
I can see a light grey area, shaped like a pie wedge, extending from the origin to the wall markers. This would seem to be cells for which the occupancy is "unknown" since it is grey. This seems strange to me that the cells have unknown occupancy, since the (fake) laser can see all the way through them right to the solid wall. Perhaps they are supposed to be "white" according to the documentation. It just doesn't look very white to me. [EDIT: it is white if I change the alpha to 1.0]. OK, this makes sense to me as well.
If I don't remove the Global Map and Local Map displays (even if they are disabled), there is yet another greyish greenish 1x1 square whose left corner is at the origin. It goes away if I remove both the Global Map and Local Map displays. [EDIT: Ahhh I just noticed that the Map shows up as a 1x1 square if I delete it (and the other 2 maps) and re-add it. It turns back into the display I described above once I subscribe to the /map topic. Furthermore, I notice that I don't have anything publishing /move_base/global_costmap/costmap and /move_base/local_costmap/costmap topics, so I expect the 1x1 square is some sort of default visualization for the Global and Local Map displays that is shown in the absence of anything rational to be displayed. OK, I suppose that makes sens now too.]
Finally, when I read the documentation, I see that the Map display has 3 parameters: Topic, Alpha, and Request Frequency.
The following is multiple choice question (with options) to answer.
Aerial maps represent what feature using dark green? | [
"the slopes of the Rocky Mountains",
"underwater ocean forests and coral",
"trees packed close together",
"The great northwestern plains"
] | C | a dense forest environment is often dark in color |
OpenBookQA | OpenBookQA-1430 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
As the flower size increases, what will it attract more of? | [
"monarchs",
"grass",
"carnivores",
"toy butterfly"
] | A | as the size of a flower increases , the number of pollinators it will attract increases |
OpenBookQA | OpenBookQA-1431 | species-identification, entomology
Title: Bug on wall identification request I've been finding a few of these on the same wall of my apartment the path month. Size is maybe 3-5 mm.
I live in an apartment in Toronto Canada.
Thanks in advance! Without clearer photos it is pretty hard to say, however, I think it is likely to be one of the Dermestidae family of beetles.
These include a bunch of common pests in the household, including "carpet beetles" (Anthrenus sp.), and the larder beetle (Dermestes lardarius).
I think this is most likely to be a carpet beetle, given the light/dark mottled pattern on the shell.
The following is multiple choice question (with options) to answer.
What color is a stick bug? | [
"brown",
"gray",
"green",
"black"
] | A | An example of camouflage is when something has the same color as its environment |
OpenBookQA | OpenBookQA-1432 | physical-chemistry, everyday-chemistry, thermodynamics
As a comparison to this example, let's check out two liquids that do mix.
3. Water and ethanol
For the water, we have basically the same situation as before -- water molecules forming good bonds to each other. The ethanol, though, has an -OH group that can form bonds to the water in the same way that the water does (though not as well). This means that ethanol that mixes with water (and vice versa) will tend to stay mixed, and given that the liquids are being mixed around just by random motions, means that you'll get one mixing with the other just as a matter of statistics.
The following is multiple choice question (with options) to answer.
An example of a true combination of mixed substances is | [
"corn with butter",
"sand and pebbles",
"cream and coffee",
"dirt and sand"
] | C | An example of combining two substances is pouring one substance into the other substance |
OpenBookQA | OpenBookQA-1433 | motor, hardware, dc
Title: Choosing the right dc motor I'm trying to find the optimal components list for a radio controlled lawn mover i'm trying to build.
The blades will be rotated by a 140 cc engine. I choose this engine because it's already mine. It's weight is 25 kg
The movement will be electrical powered by 2 battery 12v and 18 amp h
i will use arduino and 2 motor drivers. Each driver can handle 6v to 27v and a maximum of 43 amp
The following is multiple choice question (with options) to answer.
Which of the following will help my non-electric lawnmower run? | [
"UV rays",
"a cloudy day",
"dinosaur remains",
"an AC current"
] | C | oil is a source of energy |
OpenBookQA | OpenBookQA-1434 | Remark $\$ This is a special case of ubiquitous multiplicative telescopy
$$\rm \frac{a_1}{a_n}\, =\, \frac{a_1}{\color{#C00}{a_2}}\frac{\color{#C00}{a_2}}{\color{#0A0}{a_3}}\frac{\color{#0A0}{a_3}}{\cdots}\cdots\dfrac{\cdots}{\color{brown}{a_{n-1}}}\frac{\color{brown}{a_{n-1}}}{a_n}$$
-
The following is multiple choice question (with options) to answer.
An acquired characteristic is | [
"a jagged raised welt you've had since you fell down the stairs 6 years ago",
"freckles from your mom's genes",
"brown, curly hair that resembles your sister's",
"a large nose just like your dad's"
] | A | a scar is an acquired characteristic |
OpenBookQA | OpenBookQA-1435 | electromagnetism, electricity, electrons, atoms, voltage
1Actually, electrons are also small magnets themselves (they have an instrisic quantum-mechanical spin) and therefore are attracted to inhomogenic magnetic fields, but that's quite another issue.
2Actually, it would... but that's mostly relevant in the high-frequency-regime, i.e. bound electrons that jiggle back and forth very quickly.
The following is multiple choice question (with options) to answer.
What would potentially be attracted to a magnet? | [
"a zipper",
"a cat",
"a lightbulb",
"a bench"
] | A | if something contains a large amount of magnetic material then that something will attract magnets |
OpenBookQA | OpenBookQA-1436 | species-identification, zoology, entomology
Title: Species identification; clusters of big plump red bugs in Taipei I saw these red insects in Taipei near XinBeitou MRT station in the last week of April 2017, around lunch time. They were fairly active and would keep checking each other out with their antennae for a moment and then move on to the next. What struck me was the wide range of sizes and development in the groups. I didn't notice any feeding or mating that I could recognize, just a lot of walking around and checking each other out.
There are plenty of birds around (this is quite a green area) but I didn't notice any interest by birds in eating them.
I've also included a screenshot from google maps so you can see the location and the trees growing in these concrete structures.
The body of the largest individual is probably 2.5 centimeters long. I'm fairly certain these true bugs belong to the species Leptocoris vicinus, and carry the nickname of "soapberry bugs", which is specific to the subfamily Serinethinae. They're quite common in urban areas of Southeast Asia, which coincides nicely with where you encountered them.
Also, you had mentioned,
There are plenty of birds around (this is quite a green area) but I didn't notice any interest by birds in eating them.
Soapberry bugs, as well as many other types of insects, are able to freely congregate in large numbers, and in such exposed places, due to their bright coloration. Having such a bright color may indicate to some predators that the prey in consideration is toxic, a phenomenon referred to as aposematism.
source
source
And then, here's a map of their distribution, with Taipei holding marker #37. (source)
An interactive version of this map can be found here.
The following is multiple choice question (with options) to answer.
Large metropolises can have a huge bedbug | [
"sport team",
"water bill",
"dating pool",
"infestation"
] | D | an ecosystem contains large numbers of living organisms in a particular place |
OpenBookQA | OpenBookQA-1437 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Fibrous tissue contracts to | [
"show for the ladies",
"rest and repair itself",
"get other muscles out of the way",
"stretch out an arm"
] | D | muscles pull bones to move the bones |
OpenBookQA | OpenBookQA-1438 | earthquakes, seismology, instrumentation, in-situ-measurements, diy
Title: Using accelerometer as a seismograph I'm using ADXL345 accelerometer with Raspberry Pi to build a seismograph. I've successfully hooked it up and can plot the accelerometer data in three axis. Is there any way to express these data in the form of the magnitude of an earthquake, of course, at the point of sensing? I know that it might be imprecise, but any representation would be helpful (e.g. Richter scale), and how to accomplish that. The magnitude of an earthquake is related to the total energy released, therefore to estimate it from a seismogram you need to know the distance to the source. In the case of the Richter scale for example, the relationship between magnitude and seismogram amplitude is defined for a standard distance.
If you have only one seismograph, you can not triangulate the location of the source (hypocenter). Therefore, you can not estimate the magnitude of a seismic event (Richter or moment magnitude).
But you can estimate the local seismic intensity of the event at the particular location of your instrument. With the accelerometer data you can easily measure the peak ground acceleration, that can be used to estimate the intensity in any of the existing scales. For example, the peak ground accelerations associated to each intensity level in the commonly used Mercalli intensity scale are:
Those g values would be easy to calculate with the accelerometer data and proper calibration constants.
Table taken from the Wikipedia page for peak ground acceleration
You might want to have a look at this question. There are some nice answers and references that you might find useful.
The following is multiple choice question (with options) to answer.
A seismometer will be able to tell someone | [
"how wet a storm made the ground",
"how badly things were shaking",
"how loud a siren was",
"how fast a cheetah is"
] | B | a seismometer is used to measure the strength or magnitude of an earthquake |
OpenBookQA | OpenBookQA-1439 | newtonian-gravity, water, flow, fluid-statics
Title: Is there a way to fill Tank 2 from Tank 1 through Gravity alone? I am a newbie in water system design but I am currently faced with the exact situation below on my land, and I need to know whether gravity alone is sufficient in order to fill Tank 2 from Tank 1, as I already experienced backflow.
Please have a look at this image:
Note: let's not worry about how Tank 1 is being filled as it probably does not matter - I just made sure I never used a pipe diameter smaller than 0.5" between Tank 1 and Tank 2.
As you can see:
My water source is the overflow of Tank 1
I have put a 1" diameter pipe in the first 'downhill' section of my path
The second, longest section of the path is a pipe of 0.5" diameter
The system is 'powered' through gravity alone
Questions
The following is multiple choice question (with options) to answer.
A lack of water has a direct connection on the amount of available | [
"shelters",
"sustenance",
"rainy days",
"mates"
] | B | as available water in an environment decreases , the amount of available food in that environment will decrease |
OpenBookQA | OpenBookQA-1440 | 1. all chicks peck to the left. 0% of chicks are unpecked.
2. all chicks peck to the right. 0% of chicks are unpecked.
3. all chicks, divided in pairs, peck each other, 0% of chicks are unpecked.
4. chicks are divided in groups of 4, where the pair in the middle pecks each other, while chicks on the edge peck this pair in the middle. 50% of chicks are unpecked.
There are however other possible probability distributions. Two new patterns emerge from this.
1. chicks are divided into groups of 3, where a pair of chicks pecks each other and one chick from this pair is double pecked by a chick on the LEFT. This chick on the left is unpecked which makes a total of 33%. The last, 100th chick can peck randomly left or right but remains unpecked itself as in example 4). This gives 34 unpecked chicks.
2. chicks are divided into groups of 3, where a pair of chicks pecks each other and one chick from this pair is double pecked by a chick on the RIGHT. The last, 100th chick can peck randomly left or right but remains unpecked itself as in example 4). This gives 34 unpecked chicks.
A mixture of all those sets of outcomes are, of course, also possible. Now we can calculate the median of these 6 possible outcomes: (0+0+0+50+34+34)/6=19.666 somewhat lower than the original solution.
The following is multiple choice question (with options) to answer.
Weather is getting a little more chilly, so a flock makes their way | [
"elsewhere",
"north",
"Narnia",
"the moon"
] | A | An example of migration is birds flying south in the winter |
OpenBookQA | OpenBookQA-1441 | A common example of this is with $f \equiv 0$ and $g \equiv 1$, the characteristic function of the rationals which is continuous nowhere.
• This is a great reference! I have seen many variations of this type of problem, so it's very nice to have such a concise generalization. – OGBerglemir May 19 '18 at 20:13
• Thank you for the acceptance. – астон вілла олоф мэллбэрг May 20 '18 at 10:29
The following is multiple choice question (with options) to answer.
An example of an acquired characteristic is | [
"the thickness of a horse's mane",
"the length of a horse's mane",
"the number of legs a horse has",
"the color of a horse's mane"
] | B | the length of the hair of an animal is an acquired characteristic |
OpenBookQA | OpenBookQA-1442 | homework
Title: How to determine if this blood disorder is recessive or dominant? This question is from "Concepts of Genetics," Klug & Cummings, 10e.
"Thalassemia is an inherited anemic disorder in humans. Affected
individuals exhibit either a minor anemia or a major anemia.
Assuming that only a single gene pair and two alleles are
involved in the inheritance of these conditions, is thalassemia a
dominant or recessive disorder?"
I know from a quick Google search that the disorder is recessive, but how would I come to this conclusion based on the question alone?
Edit: I've spoken to my professor, and he shared his opinion that is essentially the same as canadiener's answer. Thanks to everyone that replied! Given that this is a text book question about classical genetics, you can safely disregard any reality about the disorder.
I'd argue that the two alleles show incomplete dominance. The mild anemia, which is intermediate between healthy individuals and those with severe anemia, can be attributed to heterozygous individuals. In this case, the expression of the functional allele is not enough to compensate for the nonfunctional allele, producing the mutant phenotype.
The following is multiple choice question (with options) to answer.
Which is an inherited characteristic? | [
"hair length",
"clothing style",
"bone thickness",
"language skills"
] | C | the thickness of the parts of an organism is an inherited characteristic |
OpenBookQA | OpenBookQA-1443 | climate-change, climate
In this case, as it is an area that it is almost constantly cloudy with high humidity, temperature is varying just a little bit, and except the first day of the period, it seems that there is no relationship. In fact, on the second day there was a storm (I am living now at Singapore) and it is reflected in a quick change in temperature (both) and solar radiation.
Conclusion: It is not as simple as it seems.
Hope it helps!
The following is multiple choice question (with options) to answer.
Foggy days are said to be | [
"good for skin",
"high in moister",
"extremely dry",
"very sunny"
] | B | moist means high in moisture |
OpenBookQA | OpenBookQA-1444 | 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.
Jerry put some salt into some tap water and stirred it up. What has Jerry made? | [
"a solution",
"a battery",
"sea water",
"lemonade"
] | A | a solution is made of one substance dissolved in another substance |
OpenBookQA | OpenBookQA-1445 | However, if said that an object is an apple if and only if it is a fruit ($\text{Fruit} \iff \text{Apple}$), then that would once again mean that something has to be a fruit in order for it to be an apple, but here the main difference is that it would also have to be an apple and not an orange or a banana. If it is a fruit, then it's an apple, and if it is an apple, then it is a fruit.
In the second example, we have also added $\text{Fruit} \Rightarrow \text{Apple}$ which, on it's own, means that if something is a fruit, then it has to be an apple. Another way of writing $A \iff B$ is $(A \Rightarrow B) \ \& \ (A\Leftarrow B)$.
## protected by Zev ChonolesJun 25 '15 at 6:00
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The following is multiple choice question (with options) to answer.
Some fruits are berries and have _____ visible on the outside, but others have them on the inside | [
"corn",
"songs",
"mice",
"kernels"
] | D | fruit contains seeds |
OpenBookQA | OpenBookQA-1446 | climate-change, sea-level
Title: "Five of the Solomon Islands disappeared" due to sea level rise, how is this possible so quickly? The text of the introduction to the BBC Podcast Sea Levels Rise; The Compass, Living on the Edge Episode 1 of 4 says:
Five of the Solomon Islands have disappeared, many more are becoming uninhabitable. For Kerry and Sally, climate change is not a theory - it is what has made them abandon their island and the graves of their ancestors. They see themselves as lucky - they had family land to move to and the skills to build new homes on stilts - but they are resigned to moving again.
Award-winning journalist Didi Akinyelure visits her home city of Lagos to find out the latest solution to sea level rise in West Africa. The glass towers of the new financial district of Eko Atlantic are protected from the waves by state of the art sea defences. The residents of the luxury apartments should keep their feet dry whatever the climate throws at them. That may be small comfort for their unprotected neighbours in the shanty town on the lagoon, Makoko, but they’re experts in survival against the odds.
Certainly sea level is rising, on the order of perhaps 15 centimeters in the last century judging from this plot, and the New Scientist article Five Pacific islands vanish from sight as sea levels rise certainly adds credence to this. Answers to the question Sea Level Rise due to Climate Change shed some light on human-induced climate change.
Between about 04:00 and 06:00 in the podcast, Simon Albert, a climate change scientist from University of Queensland describes the situation in the Solomons.
Here is my best attempt at a transcription of a small part of the podcast:
The following is multiple choice question (with options) to answer.
A new island springs up out of the ocean after only a couple of years of | [
"underwater buildup",
"animal testing",
"volcanic movies",
"millionaire ideas"
] | A | an island is formed by lava cooling on the ocean floor over time |
OpenBookQA | OpenBookQA-1447 | photons, photon-emission, combustion
In some cases a local bubble of high-energy plasma would be formed by the interaction. The plasma gets absorbed by the surrounding matter which is heated in turn. If this bubble is close enough to the surface so that the heated material has a chance to combust in contact with air, then yes you could ignite the piece of wood with a photon flux of 1 Hz.
The following is multiple choice question (with options) to answer.
Which of these objects could combust | [
"Seashells",
"Grass",
"A cat",
"A paint can"
] | D | high temperatures can cause an object to combust |
OpenBookQA | OpenBookQA-1448 | 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.
When a light switch is turned on | [
"brilliant sparks arc along the wall",
"the light colors are switched with the dark colors",
"ions are pushed along a copper wire",
"a cat in a box of poison dies"
] | C | when an electrical circuit is working properly , electrical current runs through the wires in that circuit |
OpenBookQA | OpenBookQA-1449 | soil, moon
Title: What is the difference between lunar and earth soil I know that the moon has lunar regolith and earth has earth soil, but what is the difference between them? The single biggest difference is the lack of chemical weathering in lunar soils which are subject to physical weathering almost exclusively. If you exclude biological processes, terrestrial rocks undergo significant weathering from water and atmosphere, which the moon lacks.
For example, both earth and moon contain feldspar-rich rocks, however, clays, the result of chemically altered feldspars, are not found on the moon. Neither are oxidized minerals, as the moon has no oxygen-rich atmosphere to speak of.
The following is multiple choice question (with options) to answer.
What can be found on the lunar surface and has been there for thousands or millions of years? | [
"mountains",
"cheese",
"the lunar rover",
"large lakes"
] | A | the surface of the Moon contains mountains |
OpenBookQA | OpenBookQA-1450 | optics, everyday-life, reflection
Title: Why can't we see images reflected on a piece of paper? Why can't you see a reflected image on a piece of paper? Say you put a pen in front of the paper, even when light rays are coming from other sources, hitting the pen, reflecting back, and hitting the paper, there is no reflection.
What's wrong with the following "ray diagram" and why such even don't happen and the image of the pen don't form on the paper (right side is a paper)?
When then can you see the image of a torch when you shine it on the paper?
When you put a convex lens in front of the pen, why you can now see the image of the pen on the paper? Because the real situation looks a lot more like this:
Your pen is (presumably) not made of mirror-like polished metal, but rather of something like wood or plastic that reflects light diffusely. This means that the light from each part of the pen is scattered all over the paper (and, of course, in other directions too), so it won't project a clear image onto the paper.
(And since the paper itself is also a diffuse reflector, all the light that hits it gets scattered in all directions again, and some of it ends up hitting your eye. If you replaced the paper with a mirror, then only those rays that were coming from just the right direction would have a chance of getting reflected towards your eye, and so you'd see a sharp reflected image.)
OK, so why won't the pen at least form a blurred image on the paper, then? Well, actually it does.
Here's a photo I just took with my cellphone. Sorry that it's a bit dark, I wanted to make sure I didn't burn out any highlights.
The following is multiple choice question (with options) to answer.
What does an object need to reflect towards the eye to be seen? | [
"lamp glow",
"water",
"light rain",
"wind"
] | A | if an object reflects light toward the eye then that object can be seen |
OpenBookQA | OpenBookQA-1451 | materials
The image is a modified version of an image found at www.geology.um.maine.edu. Original credit: Passchier and Trouw, pg 33 (2005).
The following is multiple choice question (with options) to answer.
A rock is boring, so a person wants to make it look different. A person could have it weathered by | [
"putting it in a bag",
"putting it in a yard",
"putting it in a dish",
"putting it in a tumbler"
] | D | mechanical weathering is when rocks are broken down by mechanical means |
OpenBookQA | OpenBookQA-1452 | homework-and-exercises, classical-mechanics, energy, momentum
Title: Impulse and car make (homework question) In my physics course it says that the more sturdy the car is the more momentum change (impulse) it will experience during a collision.
The following image is a snippet of the paragraph in my course that talks about this.
These different types of collisions can have a serious effect on people in cars. Usually, a car collision is inelastic or completely inelastic, if the vehicles stay together. Older cars were made to be very sturdy, with solid metal frames. This caused collisions to occur over shorter periods of time, and the cars to bounce back. These two factors increased the net force experienced by passengers because the change in momentum was larger and it happened over a shorter period of time.
Modern cars have "crumple zones" in the front and rear. These serve to lengthen the time of impact for the collision, as well as to absorb as much energy as possible, which decreases the chance that the cars will bounce off each other and increase the impulse. Both these factors decrease the net force on passengers, helping to reduce the number of injuries and deaths.
Why is this the case? Impulse should not change with the material the car is made from but only with the amount of seconds it is contact with the other car and the force (action-reaction) between the two cars. Impulse is simply the change in an object's momentum. When two cars collide and bounce off one another (an elastic collision), the impulse is greater than when two cars collide and stop (an inelastic collision). When the cars bounce off one another, they require enough impulse to stop the car, and then even more impulse to make them bounce back the way they came. The crumple zone reduces the total impulse by preventing the cars from bouncing back, as well as increasing the time and thereby decreasing the force required to achieve that momentum change. The crumple zone reduces the force felt by passengers both by reducing the total momentum change, and lengthening the time over which that change occurs.
The following is multiple choice question (with options) to answer.
Slamming the breaks in a car will | [
"make the car speed",
"quickly bring the speed down",
"turn on it's radio",
"open all the doors"
] | B | skidding causes speed to decrease |
OpenBookQA | OpenBookQA-1453 | java, reinventing-the-wheel, console, unix
With clothes the new are best, with friends the old are best.
He is truly wise who gains wisdom from another's mishap.
Beware of a dark-haired man with a loud tie.
Today is the last day of your life so far.
Flee at once, all is discovered.
Man who falls in vat of molten optical glass makes spectacle of self.
Go directly to jail. Do not pass Go, do not collect $200.
For a good time, call 8367-3100.
Those who can, do; those who can't, simulate.
Those who can, do; those who can't, write. Those who can't write work for the Bell Labs Record.
God does not play dice.
This fortune is inoperative. Please try another.
Laugh, and the world ignores you. Crying doesn't help either.
No amount of genius can overcome a preoccupation with detail.
You will feel hungry again in another hour.
You now have Asian Flu.
God made the integers; all else is the work of Man.
Disk crisis, please clean up!
You auto buy now.
Many are called, few are chosen. Fewer still get to do the choosing.
Try the Moo Shu Pork. It is especially good today.
Many are cold, but few are frozen.
The early worm gets the bird.
He who hesitates is sometimes saved.
Time is nature's way of making sure that everything doesn't happen at once.
The future isn't what it used to be. (It never was.)
Can't open /usr/lib/fortunes.
If God had wanted you to go around nude, He would have given you bigger hands.
It is better to have loved and lost than just to have lost.
A journey of a thousand miles begins with a cash advance from Sam.
Disk crunch - please clean up.
Center meeting at 4pm in 2C-543
I will never lie to you.
Spock: We suffered 23 casualties in that attack, Captain.
Your computer account is overdrawn. Please reauthorize.
1 bulls, 3 cows
It's hard to get ivory in Africa, but in Alabama the Tuscaloosa.
Waste not, get your budget cut next year.
Old MacDonald had an agricultural real estate tax abatement.
Snow Day - stay home.
Save gas, don't eat beans.
The following is multiple choice question (with options) to answer.
A person owns thousands of acres of land and would like to do something great for the environment, so he | [
"limits human access",
"limits animal access",
"builds a mall",
"starts a riot"
] | A | An example of protecting the environment is creating protected areas |
OpenBookQA | OpenBookQA-1454 | 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.
If one mineral can scratch another then the scratched mineral is what? | [
"strong",
"soft spoken",
"potent",
"mushy"
] | D | if one mineral can scratch another mineral then that other mineral is softer than that one mineral |
OpenBookQA | OpenBookQA-1455 | newtonian-mechanics, forces, planets, newtonian-gravity, tidal-effect
Title: How should I be thinking about tides? I am working on a project for physics that involves tides. This is my current mind set when thinking about tides:
The earth applies a gravitational force on some mass M. The moon & sun apply a gravitational forces on the mass M away from the earth. The bodies of water on the earth have some acceleration towards the moon & sun due to their forces (F=ma). The bodies of water accelerate till they reach a sort of equilibrium between forces.
I would like you to poke holes in my understanding of tides and try and answer my naive questions bellow.
How would you describe tides effected by the moon using forces? How can that be used to calculate the height of tides? It would be better to think in terms of water trying to flow until it reaches a equal-potential surface.
Like this. In the absence of competing forces from the sun and moon, the water doesn't rush down until the Earth stops pulling on it, it flows until there is nowhere for it to go because the other water is in the way. That happens when the surface of the water is all at a uniform value of the gravitation potential. (If it wasn't a bit of water could get "lower" by moving sideways from the "high" spot...)
The difference is that you have the Earth's gravitational potential, plus the pseudo-potential of rotation (it is only the centifugal "force" that you need worry about in this case), plus the tidal potential due to the moon and that due to the sun.
The following is multiple choice question (with options) to answer.
Tidal motion can be used to | [
"activate turbines on shore",
"rock you to sleep",
"smash waves on rocks",
"light a dark pathway"
] | A | tidal energy can be used to produce electricity |
OpenBookQA | OpenBookQA-1456 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
The circulatory system is so long it | [
"could be wrapped around the earth",
"is the length of a horse",
"is the length of the universe",
"is the length of the universe"
] | A | the circulatory system brings oxygen from the lungs to the rest of the body |
OpenBookQA | OpenBookQA-1457 | species-identification, mycology
Title: Mushroom Identificaton(USA) I need help identifying a perculiar species of mushroom found in my yard today. Color is orange-yellow, around 3-4 inches total radius, its a cluster of tiny to medium mushrooms. They were found near an oak tree. Location is southern Georgia, USa. These could be specimens of Omphalotus Illudens based on the orange/yellow color, the time of the year, their association with decaying wood (an oak in this case) and your location (eastern North America)
You can read more about these species in this reference: Messiah College
The following is multiple choice question (with options) to answer.
A pile of mulch is broken down and when searching for the culprit, a gardener notes | [
"wriggling organisms",
"writing organisms",
"large trees",
"wild fires"
] | A | decomposer is a kind of role in an ecosystem |
OpenBookQA | OpenBookQA-1458 | 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.
A person is in the forest, lost. They need to signal to others that they are there, and their voice is gone, so they need to do it inaudibly. The person may signal with | [
"fire",
"rain",
"leaves",
"ducks"
] | A | fire gives off light |
OpenBookQA | OpenBookQA-1459 | {BB, BG, GB, GG}
From these possible combinations, we can eliminate the GG combination since we know that one child is a boy. The three remaining possible combinations are:
{BB, BG, GB}
In these combinations there are four boys, of whom we have chosen one. Let's identify them from left to right as B1, B2, B3 and B4. So we have:
{B1B2, B3G, GB4}
Of these four boys, only B3 and B4 have a sister, so our chance of randomly picking one of these boys is 2 in 4, and the probability is 1/2 - as you have indicated.
So, we put all our two-child families into that room, and half the boys will be from two-boy families (two of them supplied by each such family!), and the other half will be from one-boy families. Everything is as we expect. But here, we counted boys, not families.
But now let's look at a different way of selecting the "boy" in the problem. Suppose we randomly choose the two-child _family_ first. Once the family has been selected, we determine that at least one child is a boy. (For example, from all the mothers with two children, we select one and ask her whether she has at least one son.) In this case, an unambiguous statement of the question could be:
From the set of all families with two children, a family is selected at random and is found to have a boy. What is the probability that the other child of the family is a girl?
Note that here we have a pool of families (all of whom are two-child families) and we're pulling one family out of the pool. Once we've selected the family, we determine that there is, in fact, at least one boy.
Since we're told that one child (we don't know which) is a boy, we can eliminate the GG combination. Thus, our remaining possible combinations are:
{BB, BG, GB}
Each of these combinations is still equally likely because we picked one of the four families.
Now we want to count the combinations in which the "other" child is a girl. There are two such combinations: BG and GB.
The following is multiple choice question (with options) to answer.
A person is celebrating a new baby and family is happily celebrating as well. The family is glad that the person who had the baby is | [
"a corpse",
"a child",
"a monster",
"an adult"
] | D | reproduction occurs during adulthood |
OpenBookQA | OpenBookQA-1460 | evolution, zoology
Title: Why are hens so different from other birds? Hens lay many eggs during their lifetime (at least, I don't know of one which can lay more eggs) and they can't fly. Compared to other domestic animals it seems to me they are the least capable of defending themselves or escape if it comes to be left alone in open wild. What is their evolutionary story? Domestic organisms are bred to serve specific purposes for humans. Sheep are bred to produce wool; Cows are bred to provide meat and milk for human consumption; dogs are bred for service and companionship. Since domestic animal do need to survive in the wild in order to reproduce (ignoring feral animals, which is an interesting topic by itself), most of the other aspects of that animal relevant to its survival tend to be minimized.
So one could just as easily point out that there is no other animal that produces as much wool as a sheep, and yet producing copious amounts of wool isn't particularly useful to the animal itself (i.e. other than the fact that humans will tend to select good wool producers for breeding). So sheep are not particularly good at surviving in the wild, and yet they are incredibly successful as a species and are widely distributed, thanks to humans.
In short, domestic hens evolved to produce many eggs in their lifetime because over the past millennia since humans have started keeping them as livestock, humans tended to preferentially breed those individuals which produced more eggs and to eat those individuals which did not. Chickens tended to be kept in pens and guarded by humans or other animals, so the ability to defend themselves or flee from danger was not important to their survival, and in fact, those that did attack their handlers or escape were probably less likely to be bred.
This process is known as selective breeding or artificial selection.
The following is multiple choice question (with options) to answer.
Which animal produces more eggs | [
"African Driver Ant",
"Humans",
"Monkeys",
"Goats"
] | A | as the number of eggs laid by an animal increases , the number of eggs that hatch will increase |
OpenBookQA | OpenBookQA-1461 | mechanical-engineering, structural-engineering, materials
The net kinetic energy change for object A is $(1/2)m_A (v_{f}^2 - v_{Ao}^2)$. Apply the same for object B.
As for energy absorbed by the objects individually, the answer is ambiguous. The objects cease to exist as individual objects at the moment of the collision. Any energy lost is absorbed by the final combined object, not by any one individually.
The following is multiple choice question (with options) to answer.
When an object moves, how will its kinetic energy be affected? | [
"lower",
"reduced",
"escalate",
"lessen"
] | C | as an object moves , the kinetic energy of that object will increase |
OpenBookQA | OpenBookQA-1462 | thermodynamics, fluid-dynamics, bubbles
Title: Why do steam bubbles increase in size as they rise? In the following video (a customer's review of a glass kettle), we can observe water boiling: http://youtu.be/jByY5I7Xk7w?t=2m55s
As the kettle starts to boil at around 2:55, we can see large steam bubbles being formed at the bottom, where the heating element is, and these bubbles shrink as they rise. Presumably this is because they are coming into contact with cooler water. Then we get a crazy convection current for a bit before the element switches off again.
After the chaotic motion has died down (and the fluid is presumably very well mixed) we see small steam bubbles being forming at the bottom, which grow as they rise. I can think of two possible explanations for this, and I'm curious as to which is correct:
The water is superheated. Nucleation sites exist on the bottom of the kettle, so that's where steam bubbles form. Steam is produced at the interface between steam and water, which causes the bubbles to grow as they rise.
The pressure at the bottom is slightly higher than at the top. Assuming a depth of 15cm, the boiling point at the bottom of the water is about $100.3^\circ \mathrm{C}$, compared to $100.0^\circ \mathrm{C}$ at the top. Bubbles form at the bottom because the heating element is still slightly hotter than $100.3^\circ \mathrm{C}$, and as they rise they drag hot water up into the slightly lower-pressure area, where it turns to steam because its boiling point lowers, and this increases the size of the bubble.
The following is multiple choice question (with options) to answer.
A bucket of hot water has steam rolling off of it. The steam collects on the sides of the bucket and | [
"melts",
"fries",
"pools",
"glows"
] | C | condensing causes a liquid to form |
OpenBookQA | OpenBookQA-1463 | 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.
We can thank the sloth and its feces for giving us | [
"guacamole dip",
"bacteria on lettuce",
"funny Youtube videos",
"brown rice"
] | A | plant requires seed dispersal for reproduction |
OpenBookQA | OpenBookQA-1464 | visible-light, reflection
Title: Why white flat surfaces are white and not mirror-like reflective? White color means very little optical absorption, so why a white flat surface (such as a wall) appears as white and not as a mirror-like surface? A mirror or (almost) any other well polished material, exhibit specular reflection, in which the law of reflection is observed (angle of incidence equals angle of reflection).
Virtually all materials can give specular reflection, provided that
their surface can be polished to eliminate irregularities comparable
with light wavelength (a fraction of a micrometer). (Wikipedia)
(source)
A white wall has surface irregularities larger than visible light wavelength, such that reflection occurs in all directions so no image is formed. But still a white wall appears as white because it saturates the eye with all the wavelengths reflected from it.
The following is multiple choice question (with options) to answer.
What is the most sensible reason why a stove is often just white? | [
"it scatters all photons away from it without absorbing any",
"a chef specified white makes food cook better",
"it was black until someone scrubbed all the blood off it and it turned white",
"confining a stove to any specific color is color-shaming and indicates white privilege"
] | A | if an object reflects a light of a certain color then the object appears to be that color |
OpenBookQA | OpenBookQA-1465 | python, object-oriented, random
def start_delay(self):
'''Return random delay within <start_delay_range>.'''
return random.randint(start_delay_range[0], start_delay_range[1])
def run(self):
'''Turn on the light to <brightness> after <start_delay> for <duration>.'''
if self.dimmable:
# Turn on light
indigo.dimmer.setBrightness(self.device_id,
value = self.brightness(),
delay = self.start_delay())
else:
# Turn on light
indigo.device.turnOn(self.device_id,
self.start_delay())
# Turn off light after <delay>
indigo.device.turnOff(self.device_id,
delay = self.duration())
# List of Light() objects to randomize
lights = [
Light(name='Breakfast Room', device_id=1222428814, dimmable=True),
Light(name='Kitchen Cabinet', device_id=18462733, dimmable=False),
Light(name='Hallway', device_id=93680547, dimmable=True),
Light(name='Living Room Recessed', device_id=7507220, dimmable=True),
Light(name='Stairs', device_id=1842915774, dimmable=True),
Light(name='TV Room', device_id=1569858222, dimmable=True)
]
def main():
for light in lights:
light.run()
if __name__ == '__main__':
main() This code looks good! But I still have some notes to clean it up a bit.
First, all your constants (start_delay_range, brightness_range, and duration_range) should really be part of the Light class since they're used specifically in there. If that's where they're relevant, keep them there. Plus this makes it easier to do from light_tools import Light and not be caught without necessary values.
class Light():
'''
Define a light object.
The following is multiple choice question (with options) to answer.
A light can be turned on if the | [
"circuit is complete",
"light is unplugged",
"house is destroyed",
"power is out"
] | A | completing a circuit causes electricity to flow through that circuit |
OpenBookQA | OpenBookQA-1466 | desert, pollution, pm2.5, particulates, atmospheric-dust
The inclusion of secondary aerosols, combustion particles (e.g. soot) and recondensed organo-metallic vapour can and does complicate attempts to mitigate the effects once released and would also complicate attempts to prevent the release.
It could be argued that the ultrafine fraction at 0.1 microns and less could be included under the FPM umbrella; however, as stated on the UNEP page, these are still the focus of extensive research.
There are several documents calling for the control and providing practical strategies by governmental organisations, one such document is the US EPA's Controlling
Fine Particulate Matter
Under the Clean Air Act:
A Menu of Options (2006), in which it is acknowledged that
The chemistry and physics of PM2.5 formation in the
atmosphere is incompletely understood.
also, in a practical sense,
In a perfect
world, control-efficiency and cost-effectiveness data would
be at hand; however, it is not consistently available.
and also in a scientific - practical sense:
there are important distinctions
between filterable and condensable PM2.5. Further, some
methods used to measure PM emissions reflect only the
filterable components and, to exacerbate the problem, the
filterable components vary depending on the test method
used.
The first step in any attempts to mitigate the FPM content in the air is to monitor the sources, flow, composition etc of the particles. From the EPA document:
The importance of determining source apportionment
for ambient PM2.5 in a specific area cannot be overstated;
developing a cost-effective approach to controlling PM2.5
emissions sources requires an understanding of the relative
contribution from local and regional sources. Adequate
monitoring data are needed to provide insight into the
composition of ambient PM2.5 in a given area.
A British document Fine Particulate Matter
(PM2.5) in the United
Kingdom (2012), states the reason why action is not happening fast enough reasonably well, with
The science underpinning the knowledge of PM2.5 is rapidly evolving and
remains uncertain in many areas. There is a need for rapid translation into the
policy arena of the newest results and understanding.
The following is multiple choice question (with options) to answer.
A clean air act must be followed by a | [
"web design course",
"hard drive manufacturer",
"math class",
"computer programming course"
] | B | a pollutions standard is a kind of standard for reducing pollutants emitted by factories |
OpenBookQA | OpenBookQA-1467 | classical-mechanics, lagrangian-formalism
Title: Constraint force on a rod I really hope someone will take a quick look at the following, I would just love to better understand it...
This exercise is from Arnold's "Mathematical Methods of Classical Mechanics", p. 97 in the chapter on d'Alemberts principle:
A rod of weight P, tilted at an angle of 60° to the plane of a table, begins to fall with initial velocity zero. Find the constraint force of the table at the initial moment, considering the table as
(a) absolutely smooth
(b) absolutely rough
(In the first case, the holonomic constraint holds the end of the rod on the plane of the table, and in the second case, at a given point.)"
The following is multiple choice question (with options) to answer.
A rod that is wobbling from being struck with a stick will | [
"be sold",
"be silent",
"be audible",
"be frozen"
] | C | vibrating matter can produce sound |
OpenBookQA | OpenBookQA-1468 | experimental-chemistry, safety
Title: What components of safety should be included in a chemistry laboratory experiment conclusion?
The focus of my question here is this: In a laboratory there is a Bunsen burner, a hot plate, hydrochloric acid, and concentrated ammonia. What would you mention about safety precautions?
As students of chemistry and science, we often need to write detailed conclusions about our laboratory experiments. This eventually becomes second-nature, but to have an an idea of which of the safety measures taken to include are often useful to ensure ourselves that we have not left anything out.
I believe that the following are some of the the most important components of any well written conclusion in a lab entry, something that your lab instructor will read and grade you on.
Purpose: Explain the goal and purpose of the experiment in a clear and concise manner.
Findings: Presents a reasonable interpretation of, and logical explanation for all findings pertaining to the problem and stated purpose.
Discussion: Discusses possible sources of error in detail, including their effect on the results and ways of avoiding them in the future.
Referencing experimental findings and explaining the known/expected results we were looking for. Mentioning and discussing reasons for trends, if any.
In particular my instructors last year were often interested in:
Safety: This is often what I always got marked down for. I would explain that hydrochloric acid is a caustic substance and should be treated with care to not get on your tissue by wearing clothing that does not expose skin and closed toe shoes, and to always carry out the experiment with safety goggles securely fastened. It never seems to be enough for them, even if I mention eye flush and chemical shower in case of emergencies. Should I mention to not snort or freebase it? /end sarcasm
The following is multiple choice question (with options) to answer.
Why might you want to wear safety goggles while working in a lab? | [
"Safety goggle give you x-ray vision",
"Caustic liquid man-made substances can fly up",
"They protect your eyes from the sun",
"Mosquitoes are a problem"
] | B | chemical splashing sometimes occurs during experiments |
OpenBookQA | OpenBookQA-1469 | aircraft, relative-motion, equilibrium
Further edit: I almost forgot that when I first started using the Microsoft Flight Simulator, the plane wouldn't go where I pointed it, which made it very hard to land. It would always drift off center.
Later I learned a fundamental difference between cars and planes.
Cars go where they are pointed.
Planes go where they are carried.
There's always some sort of wind, so the way you get where you're going is by looking at the ground to see where you're being carried.
If you are going to the right of where you want to go, you adjust your heading to the left, and vice versa.
You never do it by pointing the plane at your destination, except in a general sense.
I only mention this because not having that understanding could have led to the OP's question.
The following is multiple choice question (with options) to answer.
A goose needs to move to warmer states for the winter. Leaving its summer home, it heads out without a map, because it can always find the right way by using | [
"the World's great patterns",
"the Earth's magnetic patterns",
"a map it buys later on",
"a compass that points north"
] | B | Earth 's magnetic patterns are used for finding locations by animals that migrate |
OpenBookQA | OpenBookQA-1470 | energy
Title: Is throwing matter from the moon to the earth a way to generate energy? If I by some mean threw lunar soil in the earths direction, and used it to power some turbines, would the turbines generate more energy than it took to get the lunar soil out of the moons orbit?
For example:
Assuming I can convert all the kinetic energy from the moon dust to electricity.
If I had an x amount of explosives (enough to produce debris that escape the moons orbit towards the earth) and I could convert the explosives energy to electricity, would I get more energy from the explosives or from using them to blow up the moon and using the debris to power my turbine? At a pure physics level, you're correct. The potential energy of the earth-moon system is decreased by moving a small mass from the moon to the earth. Therefore you can construct some mechanism to extract the energy from that different state.
But at an engineering level, this is very difficult. There's no cable or conveyor connecting the earth and the moon. So pulling mass from the moon requires expensive and fragile machines. The energy gained from this process is much less than what is required to put the machines on the moon to start the process.
Without a space elevator, we don't have a method to easily extract energy from bringing objects from space to earth. Instead objects speed up as they approach the earth, and this speed causes problems either penetrating the atmosphere or on reaching the surface. So just "throwing" doesn't create useful energy. It just heats the atmosphere as the objects burn up on re-entry. You mention turbines, but I don't see how the turbines would be fed.
The following is multiple choice question (with options) to answer.
If I wanted to get energy what could I do? | [
"Eat a cucumber",
"Go running",
"Eat dust",
"Go swimming"
] | A | having food has a positive impact on an organism 's health |
OpenBookQA | OpenBookQA-1471 | everyday-life, ice
Title: Why are some parts of this ice block cloudy and other parts clear? I had a sprain in my leg a few days back. The doctor recommended dipping my foot alternately in ice-cold and hot water to aid blood circulation. It is here that I discovered something interesting.
The picture above shows the piece of ice that was put in the bucket. The above picture shows the ice cube from above.
If you look at the large piece of cube from the side (see below), you can see that the upper part of the cube, that was near the open surface of the container in which the ice froze, seems to be almost transparent and has a crystalline appearance. The lower part does not have this appearance, and it is white and opaque.
Why is there a difference in the layers of ice in the large cube? Is it because the water was from tap and not completely pure? The water was put in the refrigerator for a period greater than 12 hours, so the ice has frozen properly. Can anyone explain this unique structure of ice? I've never seen this before.
Update:
This update is to simply demonstrate the bubble formation in the ice,which causes the cloudiness. Out of the two answers, I had accepted the one by @IliaSmilga . Today, the ice formed demonstrated this idea clearly. Given below are the pictures in which the bubbles of dissolved gas are clearly visible.
The following is multiple choice question (with options) to answer.
giant walls of froze H2O carved out | [
"the great plains",
"the pacific ocean",
"the great lakes",
"the grand canyon"
] | C | the Great Lakes were formed by glaciers moving over the ground |
OpenBookQA | OpenBookQA-1472 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
The Earth may lose a million parts of energy each day but | [
"it loses more",
"it has less",
"it gains more",
"it is soft"
] | C | the Earth absorbs more energy than it loses |
OpenBookQA | OpenBookQA-1473 | behaviour
Title: What happens to silverfish when we throw them out the window? I'll find a silverfish from time to time in my flat. I don't mind them but usually I catch them and throw them off the balcony (second story) into the bushes and lawn below.
I was wondering, since they seem to live in the water conduits in the house, if they can survive outside or if they die/get killed instantly.
Thx for your help! Silverfish prefer high humidity and warmth. Ctenolepismacalvum (Ritter, 1910) was recently found in Japan at a temperature of 20-30°C and 50-60% RH. As long as there are pieces of bark, wet grass or other organic or human-made structures that retain humidity after each raining event, the likelihood that they will survive long enough to complete their cycle is high.
They could face dessiccation if they are not able to find a damp spot in time, depending on their tolerance to it. However, it was not possible for me to find information about their dessiccation tolerance.
The Zygentoma (silverfish order) have high tolerance to low humidity and most of the species inhabit dry and hot environments (it's just a few that like humidity), which again makes me think that those silverfish propelled out the window will survive.
The following is multiple choice question (with options) to answer.
Mice live in holes where? | [
"pastureland",
"lakes",
"oceans",
"skyscrapers"
] | A | mice live in in holes in the ground in fields |
OpenBookQA | OpenBookQA-1474 | geology, crust, geobiology
Title: Does crustal thickness have anything to do with how life existed and sustained on Earth? The original question that was put on hold "If the crust were the thickest layer of Earth, what effect would its thickness have on organisms?" was actually one of those 'counterfactual question' found on my science book, and it was really just a 'reflect upon' question. And it's actually a hard one for me to answer since it's 'what if?'s. So by revising, it would still confuse some poeple, but I guess it's already specific on its own. But I still find it hard.
Follow up question:
And what if it ever was thicker than the mantle or the rest of Earth's layers, can the planet still sustain biological life? If the crust were the thickest layer or Earth, several things would happen:
It wouldn't be a "crust" any more, by definition. Because this is what a "crust" is: a thin layer on the exterior of something. However, if we assume that the mechanical properties of the crust (being cold and brittle etc) would extend deeper in the Earth, the following applies.
No mantle convection, or at least mantle convection weak enough to probably not affect the surface. Therefore, no volcanoes, no mountain building, no subduction, no recycling of volatile elements, no sub-seafloor hydrothermal vents.
If it's cold enough, the core probably solidified and there is no magnetic field.
A good example would be Mars. A planet hypothesised to have tectonic activity in the past, but not any more. The crust of Mars isn't the thickest layer (again - think of definitions), but it is thicker in absolute and relative terms when compared to Earth. I will leave the implications of "Marsifying" Earth on organisms for you to figure out.
The following is multiple choice question (with options) to answer.
Just below the Earth's crust is something that sounds like it should be over a | [
"window",
"house",
"door",
"fireplace"
] | D | the mantle is located just below Earth 's crust |
OpenBookQA | OpenBookQA-1475 | c, game-of-life
void wait(float s) {
int now = clock();
int then = clock() + (CLOCKS_PER_SEC * s);
while(clock() != then) {
}
}
int main() {
bool** board = emptyBoard();
printArray(board);
printf("--------------\n");
initialPosition(board, "0000000000000000000000000000000000000000000000000"
"0000000000000000000000000100000000000000000000000"
"0000000000000000000000010100000000000000000000000"
"0000000000000110000001100000000000011000000000000"
"0000000000001000100001100000000000011000000000000"
"0110000000010000010001100000000000000000000000000"
"0110000000010001011000010100000000000000000000000"
"0000000000010000010000000100000000000000000000000"
"0000000000001000100000000000000000000000000000000"
"0000000000000110000000000000000000000000000000000");
printArray(board);
while(true){
//sleep(1);
wait(0.25);
printf("\e[1;1H\e[2J");
board = step(board);
printArray(board);
}
freeArray(board);
} Here are some things that may help you improve your code.
Fix the bug
The code currently includes this line in initialPosition:
*(emptyBoard[i] + j) = (bool) (startPos[(i * width) + j] - '0');
The following is multiple choice question (with options) to answer.
A student waiting for class to be over, in the last minute until the bell rings | [
"watches a UFO",
"works at factories",
"counts down portions",
"sleeps at home"
] | C | seconds are used to measure time |
OpenBookQA | OpenBookQA-1476 | agriculture
The primary cereals for making bread are wheat and rye, while barley and oats may be mixed in. Historically significant portions of the rural population of Europe were sustained by cereal-based food in the form of gruel and porridge rather than by bread, especially prior to the introduction of the potato. Barley can be consumed in the form of pearl barley and groats and oats in the form of oatmeal. Especially in cool and humid climates not very suitable for cultivating wheat and rye, oats were once commonly cultivated and consumed. When Samuel Johnson wrote his dictionary, he famously defined oats as: "A grain which in England is generally given to horses, but in Scotland supports the people." A major historical and modern use of barley has been as malted barley, the main ingredient in beer brewing.
In the case of Finland it is interesting to note how late the transition from slash-and-burn agriculture to the use of permanent fields occurred. According to Teija Alenius, Environmental change and anthropogenic impact on lake sediments during the Holocene in the Finnish − Karelian inland area, Ph.D. thesis, University of Helsinki, 2007 (online)
The following is multiple choice question (with options) to answer.
Locusts historically always affect crops | [
"in the sky",
"disadvantageously",
"near water",
"positively"
] | B | insects can have a negative impact on crops |
OpenBookQA | OpenBookQA-1477 | agriculture
Title: What does "permanent field" mean in agriculture? I am reading a book that in a paragraph talks about the agricultural methods used in prehistoric Finland.
The further north and east, the more extensive the amount of
burn-beat cultivation, which was a far from primitive form of
agriculture. The yield was many times higher (twenty- to thirty-fold)
than on permanent fields (five- to ten-fold), and there were multiple
varieties of the technique
A history of Finland by Henrik Meinander.
One of them is burn-beating. Like I understand, in burn-beating people cut down the trees in the forests and burn the topsoil. This way they can use that soil for 3 to 6 years for cultivation.
The other method is permanent field. I have searched the internet and the result I got was "permanent crops", like here. In which case people planted trees once in a field and harvested them multiple times.
But in another research about prehistoric Finland it was saying:
The site of Orijärvi shows that permanent field cultivation, with
hulled barley as the main crop was conducted from approximately cal AD 600 onwards.
The following is multiple choice question (with options) to answer.
A farmer's potato crop all dies and is gone to waste. The farmer looks in the field closely and can tell that the crops were destroyed by | [
"Jupiter",
"all",
"flowers",
"bugs"
] | D | insects can have a negative impact on crops |
OpenBookQA | OpenBookQA-1478 | metabolism, human-anatomy, pharmacology, liver
For drugs introduced through an injection, for example, metabolism occurs throughout the circulatory system and in the liver. Remember that it's all the same blood supply, but the first-pass effect just refers to the blood that goes to the liver before entering the systemic circulation (by which it can travel to its target).
The following is multiple choice question (with options) to answer.
A chemical change is likely to happen in which body part? | [
"stomach",
"heart",
"leg",
"ear"
] | A | An example of a chemical change is acid breaking down substances |
OpenBookQA | OpenBookQA-1479 | 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.
An organism passes from the world and so it | [
"has croaked",
"has money",
"has health",
"has flown"
] | A | if a living thing dies then that living thing is dead |
OpenBookQA | OpenBookQA-1480 | 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 toad would have better hiding places | [
"on a house rooftop",
"in a glass bottle",
"on a forest floor",
"with a parachute skydiving"
] | C | camouflage is used for hiding by animals against predators |
OpenBookQA | OpenBookQA-1481 | inorganic-chemistry, crystal-structure, geochemistry, glass, minerals
You are correct. The main difference is that sand is crystalline and glass is not—it is amorphous.
The main component (> 95%) of common yellow sand is quartz (the mineral whose composition is SiO2). Note that not all sand is quartz. There are white sands containing calcite (CaCO3) and black sand (containing various heavy minerals). But the most common sand is indeed quartz sand: SiO2.
Glass, the type you see in your everyday life, on the other hand, is not composed of pure SiO2. It has a bunch of other additives such as Na, K, B, and others. This is done to modify the properties of the glass and make it more suitable for human use. It doesn't matter much though for our discussion.
So if they are made of the same thing, why the difference? The answer is cooling rate. If you cool molten SiO2 slow enough, the atoms have enough time to organize themselves into a crystalline structure. In the case of pure SiO2, this is a network of SiO4 tetrahedra: One silicon atom surrounded by four oxygens. If it cools too fast, then the crystalline structure does not form. It may be completely amorphous, or form into a sub-microscopic array of SiO2 crystals in various structures (CT-opal for example).
What determines the cooling rate? Well, in the case of glass it is a matter of minutes. You've seen glass making: The glass is molten and very quickly it solidifies to a solid. In contrast, most of the quartz sand you're seeing is actually broken fragments of rocks called granite. This type of rock has abundant quartz in it, and it forms deep underground (as in 10s of kilometers) at very slow cooling rates. While a glass maker can take his glass and let it cool in the atmosphere or in water, molten silicate magma ("glass") deep in the Earth is surrounded by rocks that are in the hundreds of degrees. This slow cooling facilitates crystallization of the SiO2 into quartz rather than glass. How slow is this? At least tens of years, more commonly hundreds or even thousands of years. This is much slower than the seconds and minutes in glass making.
The following is multiple choice question (with options) to answer.
Sand dunes are made of | [
"nitrogen rich top soil",
"giant hills of tiny beads",
"the raw materiel that makes glass",
"small groups of parasites"
] | C | sand dunes are made of sand |
OpenBookQA | OpenBookQA-1482 | the-moon, earth, light, satellite
Title: Why does the Moon appear gray when passing between the Sun and the Earth? Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth?
The photo was taken by DSCOVR at Lagrange point 1.
In the picture, The Moon appears dark gray. Of course the Earth appears bright, reflecting sunlight from clouds and water. The Moon's surface is gray and should reflect less light than the Earth.
It should be irrelevant that we see the far side, since the reflectivity of the Moon's surface should be the same on the far side as the side that faces the Earth.
The midnight full Moon appears much, much brighter as seen from Earth than it does in this picture, despite the fact that the amount of sunlight reflecting from the surface of the Moon is the same in both instances.
I understand the photo was taken with 3 separate exposures of red, blue and green, but this should not affect the brightness.
So why does it appear so dull? That's what it really would look like if you were there with DSCOVR. The albedo of the Moon is only about 0.136, about half of the Earth's average albedo. Of course the part with clouds is higher.
I was shocked too, but it was explained in written copy that accompanied the release of the original image.
Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth?
It does. If the moon were a diffuse, white ball, a full moon would be about seven times brighter!
If you watch the image or GIF, the Moon is roughly the same brightness as central Australia or the Sahara region.
Phil Plait explains well in Bad Astronomy.
There's a lot to read here.
EDIT: I just ran across these images of astronauts on the surface while reading this answer. Their suits are not 100% white to begin with, but the Lunar soil - at least in these locations - is significantly darker. It is close to the same color as the (presumably) nearly-black radiator fins for the heat sink of the RTG unit (2nd photo) at the astronaut's foot.
above: "Buzz Aldrin carries the EASEP." from here
above: "Astronaut Alan L. Bean from Apollo 12, put the Plutonium 238Pu Fuel from the Lunar Module into the SNAP 27 RTG" from here.
The following is multiple choice question (with options) to answer.
The moon's surface | [
"features of variety of landscape features",
"is covered completely in water",
"is 100% flat and smooth",
"is 100% covered in asteroid created craters"
] | A | the moon 's surface contains highlands |
OpenBookQA | OpenBookQA-1483 | climate-change, oceanography, paleoclimatology, paleontology, climatology
As abundant as they are in living form, diatoms are generally poorly (and unreliably) preserved in an older oceanic fossil record. Importantly, they evolve rather quickly making tracking chemical changes in a single species over time and space impossible. Bulk chemistries may be obtained from fossilized silicic masses and serve as rough indicators of overall diatom abundance and thus system health.
They are, however, used in novel ways: some diatoms live exclusively in sea ice and can be used to assess duration and distribution of that sea ice, itself a record of sea surface temperature (SST):
Diatoms in Arctic regions: Potential tools to decipher environmental changes
SIDEBAR. Diatoms as Sea Ice Proxies
By contrast, forams are well preserved in the fossil record, have a well calibrated evolutionary record, and as carbonates, contain important isotopes whose ratios are sensitive to SST.
The following is multiple choice question (with options) to answer.
Where would you be most likely to observe the most diverse of all marine ecosystems? | [
"The Sahara Desert",
"off Australia's shore",
"silicon valley",
"Pacific Northwest"
] | B | coral lives in the ocean |
OpenBookQA | OpenBookQA-1484 | photosynthesis, botany
Title: Photosynthesis - Light Intensity Say I was conducting an experiment for photosynthesis. If I moved light closer to the plant, what effect would this have on the process of photosynthesis? The rate of photosynthesis varies from plant to plant. Some plants require more light and some require less. If you move light closer to the plant, in most scenarios the rate of photosynthesis is likely to be increased. For some plants a minimal light is enough for their photosynthesis, so for those plants, moving light source closer or further will have less effect.
The following is multiple choice question (with options) to answer.
What can perform photosynthesis? | [
"animals",
"people",
"water",
"shrubs"
] | D | plant cells can perform photosynthesis |
OpenBookQA | OpenBookQA-1485 | 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.
what sheds fur in warm weather? | [
"A Great Dane",
"a lizard",
"a bird",
"a fish"
] | A | some animals shed fur in warm weather |
OpenBookQA | OpenBookQA-1486 | the-moon, moon-phases
Title: Red cresent moon Yesterday night i witnessed something very strange when i looked outside the window. I saw the moon (crescent) but it was dull red and right on the horizon ,which is strange considering that it is usually on the upper right of the night sky and white in colour. On further inspection with my binoculars i noticed it was lowering down until it was hidden by the mountain range (5km away) next to my building, this all occurred within a few minutes (about 5).
Tonight i saw the moon (crescent) had again returned to its normal position.
Please explain the cause for this, i'm completely baffled!
(Sorry for the poor wording, i'm not familiar with all the astronomical terms!) The dull red color has been due to atmospheric causes, like the reddish sun close to sunset. There hasn't been an astronomical reason for the reddish color.
A few days after New Moon moonset occurs short after sunset, so you won't see the Moon high over the horizon at those evenings. With each day the Moon is a little higher above the horizon after sunset. It's hence less close to the horizon at the same time of the day. Less close to the horizon means less atomospheric absorption/scattering responsible for the dull red color, assuming the same weather conditions.
At Full Moon the Moon is at the opposite side of the Sun relative to Earth. Moon is then rising shortly after sunset.
The following is multiple choice question (with options) to answer.
the moon rising occurs | [
"once in a decade",
"4 times a year",
"7 times a week",
"1 time a month"
] | C | the moon rising occurs once per day |
OpenBookQA | OpenBookQA-1487 | space, exoplanets
http://www.rtlnieuws.nl/buitenland/nieuwe-planeet-ontdekt-buitenaards-leven-dichterbij-dan-we-denken
This sounds very unlikely to me. I calculated that you'd have to fly at about 0.14c. Our current fastest space probe (New Horizons) achieves around 0.00001c.
How likely is it that, within the next 20 years, we can launch a probe that can reach Proxima B in 30 years? I wrote a little book on this topic, that was meant to be more of a way of presenting some elementary physics than as a serious proposal for interstellar spacecraft. The main approach that I discuss is the photon sail, which is similar to these latest proposals. These proposals involve high powered lasers, while I discussed large space-based Fresnel lenses that concentrate and columate solar radiation. The underlying physics is much the same. I also discuss how you might want your spacecraft to slow down as it approaches the target star.
A photon sail I think could be pushed to $\gamma~=~2$, or more plausibly $1.15$ or $v~=~.5c$. That is one advantage I think that space-based Fresnel lenses might have. There is little need to push a photon sail any faster, for $\gamma~=~2$ is $v~=~.87c$ and there is little advantage for Earth based observers to send it much faster. That upper “limit” is probably an ideal. There is also the problem of accelerating to the final speed of the craft and so forth.
The following is multiple choice question (with options) to answer.
A shuttle quest to Earth's light source would take lots of | [
"muscle and time",
"navigation and speed",
"speed and light",
"fuel and time"
] | D | the stars in the night sky are very far away from the Earth |
OpenBookQA | OpenBookQA-1488 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
Flora requires chlorophyll to | [
"moonlight",
"undergo natural development",
"starlight",
"dairy"
] | B | a plant requires photosynthesis to grow |
OpenBookQA | OpenBookQA-1489 | experimental-physics, water, fluid-statics
Title: Determine water level difference in two ponds I live near two ponds whose water levels appear to differ by a few feet. The ground is hard clay, so I don't think there's any underground water exchange between the ponds. The ponds are separated by about 30 feet of a bumpy terrain, with the bumps reaching a few feet above the "higher" water level. What is the cleverest way to determine the difference in water levels between these ponds? What comes to mind is to stick two poles (several feet high) at the water line in each pond, stretch a string between them, level the string with a bubble level and measure the distances between the string and the water level on each pole. Any other ideas? Fill a garden hose with water. Hold both ends closed, and walk to the "higher" pond. Have someone helping you hold the end of the hose under water.
Now walk to the other pond (still holding the end of the hose shut). Hold the hose near the surface of the pond - you should feel water pressing against your finger. Make a very small opening and observe the water coming out.
Now raise the hose slowly. At the point where the water stops flowing, the end of your hose is at the level of the higher pond.
Measuring the height difference is now trivial.
Incidentally - you mentioned that the ground between the two ponds was "bumpy". This raises the question of whether this bumpiness affects the result.
What we have here is a siphon: if the water is not flowing, the pressure at any point along the hose is simply given by the height of the point relative to the level of the body of water that the inlet of the hose is submerged in. In fact, the pressure will be
$$p = p_0 - \rho g h$$
Where $\rho$ is the density of water (usually 1000 kg/m3), $g$ is the gravitational acceleration (9.8 m/s2) and $h$ is the height above the pond level. As you can see, when $h$ becomes greater than 10 m the pressure will become negative: this means the water will boil (evaporate), creating a bubble in the hose. At that point, the relationship is no longer simple. On the other hand, if the hose goes through a valley, the local pressure will be higher - but this will not matter in the end.
The following is multiple choice question (with options) to answer.
A pond is in the middle of a back yard. There are heavy rains and the pond swells and floods. The pond now _______ of the yard. | [
"takes up very little",
"takes up almost zero",
"takes up a smaller minority",
"takes up a greater portion"
] | D | as the level of water rises , the amount of available land will decrease |
OpenBookQA | OpenBookQA-1490 | java, object-oriented, state-machine
@Override
public Critter update(Ocean currentTimeStepSea){
int neighborSharkCount=0;
neighborSharkCount = Utility.countSharkAsNeighbor(this, currentTimeStepSea);
//Updating fish cell for current & next time step
if(neighborSharkCount ==1){
/*
* 4) If a cell contains a fish, and one of its neighbors is a shark, then the
* fish is eaten by a shark, and therefore disappears.
*
*/
return new Empty(this.getLocation().getX(),this.getLocation().getY());
}
else if(neighborSharkCount > 1){
/*
* 5) If a cell contains a fish, and two or more of its neighbors are sharks, then
* a new shark is born in that cell. Sharks are well-fed at birth; _after_ they
* are born, they can survive an additional starveTime time steps without eating.
*
*/
return new Shark(this.getLocation().getX(),this.getLocation().getY(),0);
}
else {
/*
* condition is (neighborSharkCount < 1)
* 3) If a cell contains a fish, and all of its neighbors are either empty or are
* other fish, then the fish stays where it is.
*/
return this;
}
}
}
/* Ocean.java */
package Project1;
/**
* The Ocean class defines an object that models an ocean full of sharks and
* fish.
* @author mohet01
*
*/
class Ocean {
/**
* Define any variables associated with an Ocean object here. These
* variables MUST be private.
*
*/
//width of an Ocean
private int width;
//height of an Ocean
private int height;
The following is multiple choice question (with options) to answer.
A creature that sometimes attaches to sharks is | [
"another shark",
"a ray-finned fish",
"a jellyfish",
"a turtle"
] | B | remora fish eat food by attaching themselves to sharks and eating the food left behind |
OpenBookQA | OpenBookQA-1491 | physical-chemistry, color, light
Title: Colour due to transmission and reflection It makes sense to me that when looking through a sample (observer | sample | light), it should appear as the opposite of the light absorbed, but it does not make sense to me to expect the same when not looking through it, just standing by the same side as the light source (observer | light | sample, or light | observer | sample).
In the first cenario, the observer sees light emitted - light absorbed (the transmitted, that barely interacts with the sample). In the second, the observer sees light reflected (to my understanding, light emitted from the de-excitations of excitations caused by the light source).
However, when I see a solution of $Cu^{2+}$, it looks the same when observed in both settings. Thereby implying that transmitted colour = reflected colour. Why is that?
Somewhat related question but without a satisfactory answer: Transmission, absorption, and reflection of light Since your experimental observation with copper salts negates your original hypothesis, it implies that the way you are trying to explain it is wrong. The main culprit and the source of all these problems is the color wheel which is taught in schools. Misconceptions persist for long. When you are looking at the copper solutions in two different settings, it is misleading to think that copper solution is reflecting blue light back to you. It is not.
In each case, copper(II) solution is absorbing a small portion of the red light from the visible spectrum and it appears to you like a pure blue solution.
Indeed it is our brain which has been created in such a way that when the visible spectrum has a certain red portion missing, it perceives the remaining spectrum as "blue".
Hint: Water in the ocean also appears blue? Water also very very weakly absorbs the red portion of the visible spectrum. You just need tons of water to perceive this effect.
There is a beautiful book by the name of The Physics and Chemistry of Color. The same author wrote an article "The fifteen causes of color: The physics and chemistry of color." It is certainly worth consulting. Article-behind paywall
The following is multiple choice question (with options) to answer.
A blue colored item will only reflect | [
"all colors in the spectrum",
"only the color white",
"a combination of colors",
"an exact matching color"
] | D | if an object is blue then that object reflects only blue light |
OpenBookQA | OpenBookQA-1492 | thermodynamics, water, phase-transition, everyday-life
Title: Why is there more steam after a pot of water *stops* boiling? I have a pot of vigorously boiling water on a gas stove. There's some steam, but not alot. When I turn off the gas, the boiling immediately subsides, and a huge waft of steam comes out. This is followed by a steady output of steam that's greater than the amount of steam it was producing while it was actually boiling.
Why is there more steam after boiling than during boiling? Also, what's with the burst of steam when it stops boiling? I have read that true steam is clear (transparent) water vapor. According to this theory, the white "steam" you see is really a small cloud of condensed water vapor droplets, a fine mist in effect. So what you are seeing is not more steam, but more condensation and more mist. The speed with which the steam/vapor/mist rises and disperses may also change.
The following is multiple choice question (with options) to answer.
Above a stove, where a pot of water boils, is a hood. The steam from the pot rises to the hood and | [
"gathers up",
"burns up dry",
"freezes solid",
"makes zero sense"
] | A | beads of water are formed by water vapor condensing |
OpenBookQA | OpenBookQA-1493 | biology, dimensional-analysis, scaling
short example as Sonny asked for in comment:
ant with 10 mm length & 10 mg mass
$\Rightarrow$ lets scale up to human size (2m) $\Rightarrow$ means a factor of 200. So the mass scales with 200x200x200=8000000 (Volume $\propto$ $l^{3}$ ) $\Rightarrow$ human sized ant=80 kg. But muscle forces scales only by factor 200x200=40000. The small ant can carry 100x10mg of her own mass=1g, the human sized ant should be able to carry 1g x 40000=40 kg.
Conclusion: pretty comparable to a avg. 80 kg human man able to carry 40 kg!
The following is multiple choice question (with options) to answer.
a carpenter ant requires energy for | [
"studying",
"yoga",
"growth",
"patience"
] | C | an organism requires energy for growth |
OpenBookQA | OpenBookQA-1494 | Method 2:
Since @Buraian wants equations with the method @Daniel Griscom suggested, here they are: Consider the part of the string that is in contact with the pulley. It experiences a force $$T$$ downwards and $$T$$ towards the left. Say the pulley applies a force of $$N_1$$ on the string ( towards upper right). By Newton's third law, the string applies $$N_1$$ on mass $$M$$ (towards bottom left).
Since $$m_1$$ doesn't swing, the rail (part of mass $$M$$) applies a force $$N_2$$ (towards left) on $$m_1$$ and $$m_1$$ applies a force of $$N_2$$ on $$M$$ towards right. Let $$M$$ (and $$m_1$$)accelerate with $$a^{'}$$, horizontally.
Since the net force on a mass less string is always $$0$$, $$N_1cos(45^0)=T \tag{4}$$ from eq(1),eq(0) and eq(4) we can get the value of $$N_1$$.
Equation of motion for $$M$$: $$N_1cos(45^0)-N_2 = Ma^{'} \tag{5}$$ Equation of motion for $$m_1$$ (X direction ): $$N_2=m_1a^{'}\tag{6}$$
Needless to say, by eq(5) and eq(6) we can obtain all the quantities and predict the motions of blocks. we get $$a^{'}$$ which is the same as $$\ddot{X}=m_1m_2g/((m_1+m_2)(m_1+M))$$ from first method.
Okay the pulley would definitely move, I will set up the laws to be used to show that it will.
The following is multiple choice question (with options) to answer.
A simple pulley example could be | [
"Going running on a treadmill",
"Swimming lap in a pool",
"Riding a bike outside",
"pulling water from a well"
] | D | a pulley is used to lift a flag on a flagpole |
OpenBookQA | OpenBookQA-1495 | 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.
A large body of salty water drying up is responsible for the creation of the | [
"salt flats",
"salt water taffy",
"Rocky mountains",
"ocean winds"
] | A | An example of a change in the Earth is an ocean becoming a wooded area |
OpenBookQA | OpenBookQA-1496 | That would be a total of 5x30 + 3x40 + 2x60 = 390 plants (with an arbitrary factor that we'll set to 1 without loss of generality).
The amount of highbush is 5x30 = 150.
The amount of lowbush is 3x40 = 120.
The amount of hybrid is 2x60 = 120.
If the opossums didn't care, they would likely eat blueberries in this ratio (null hypothesis H0).
The total that we have observed the opossums to eat is 5% x 150 + 10% x 120 + 20% x 120 = 43.5 plants.
They eat 5% large, which a corresponding fraction of 5% x 150 / (5% x 150 + 10% x 120 + 20% x 120) = 17%
They eat 10% low for 10% x 120 / (5% x 150 + 10% x 120 + 20% x 120) = 28%
They eat 20% hybrid for 20% x 120 / (5% x 150 + 10% x 120 + 20% x 120) = 55%.
Checking... yes the total is 100%.
What we see is that the opossums prefer hybrid by far.
Small blueberries are their second choice.
Last edited:
#### anemone
##### MHB POTW Director
Staff member
Hi anemone!
What do you mean by the symbol E?
Anyway, you've found that the opossums eat 45.8% large and 54.2% small for a total of 100%.
But... what happened to the hybrid blueberries?
By the symbol E, I meant the blueberries (all 3 types of them) that are eaten by opossums...
That would be a total of 5x30 + 3x40 + 2x60 = 390 plants (with an arbitrary factor that we'll set to 1 without loss of generality).
The amount of highbush is 5x30 = 150.
The amount of lowbush is 3x40 = 120.
The amount of hybrid is 2x60 = 120.
If the opossums didn't care, they would likely eat blueberries in this ratio (null hypothesis H0).
The following is multiple choice question (with options) to answer.
A squirrel eats all of the acorns in a tree. The tree is empty, and the squirrel is still hungry, so | [
"the squirrel studies",
"the squirrel leaves",
"the squirrel breeds",
"the squirrel flies"
] | B | as the supply of food in an environment decreases , the population of animals in that environment will decrease |
OpenBookQA | OpenBookQA-1497 | 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.
One way humans cause pollution | [
"using solar energy",
"walking outside",
"riding a bike",
"using antibacterial soap"
] | D | humans cause pollution |
OpenBookQA | OpenBookQA-1498 | biochemistry, ecosystem
The main damaging effects of wood ash are if it is applied in high concentrations where it can directly enter water sources (see for example UGA extension). In this case, it can raise pH enough to be damaging to life. Large quantities from large fires can also raise pH substantially in streams and such (see for example Burton, C. A., Hoefen, T. M., Plumlee, G. S., Baumberger, K. L., Backlin, A. R., Gallegos, E., & Fisher, R. N. (2016). Trace elements in stormflow, ash, and burned soil following the 2009 Station Fire in Southern California. PloS one, 11(5), e0153372.).
Eventually, however, there are enough sources of acid in the environment that there is no way the salts are permanently alkaline from the perspective of the whole environment.
The following is multiple choice question (with options) to answer.
How does erosion impact a river? | [
"enlargening",
"warming",
"heightening",
"shrinking"
] | A | erosion causes a river to become deeper and wider |
OpenBookQA | OpenBookQA-1499 | homework-and-exercises, friction, free-body-diagram
I tried to solve the exercise in this way but it's not correct, and I am probably missing something.
Can anyone help me to understand what are the forces due to friction acting in this situation?
By the way, is the expression of $F(A)$ correct?
The following is multiple choice question (with options) to answer.
Which activity involves exerting force on an object with a foot? | [
"basketball",
"kickball",
"softball",
"volleyball"
] | B | if an object is kicked then force is exerted on that object |
OpenBookQA | OpenBookQA-1500 | javascript, beginner, game
<body>
<canvas id="game-canvas" height="600px" width="800px" </canvas>
<script type="text/javascript">
var canvas = document.getElementById("game-canvas"),
ctx = canvas.getContext("2d"),
ballR = 10,
x = canvas.width / 2,
y = canvas.height - 30,
dx = 3,
dy = -3,
pongH = 15,
pongW = 80,
pongX = (canvas.width - pongW) / 2,
rightKey = false,
leftKey = false,
brickRows = 3,
brickCol = 9,
brickW = 75,
brickH = 20,
brickPadding = 10,
brickOffsetTop = 30,
brickOffsetLeft = 30;
var bricks = [];
for (c = 0; c < brickCol; c++) {
for (r = 0; r < brickRows; r++) {
bricks.push({
x: (c * (brickW + brickPadding)) + brickOffsetLeft,
y: (r * (brickH + brickPadding)) + brickOffsetTop,
status: 1
});
}
}
// function to draw the ball
function drawBall() {
ctx.beginPath();
ctx.arc(x, y, ballR, 0, Math.PI * 2);
ctx.fillStyle = "red";
ctx.fill();
ctx.closePath();
}
// function draw the pong
function drawPong() {
ctx.beginPath();
ctx.rect(pongX, canvas.height - pongH, pongW, pongH);
ctx.fillStyle = "blue";
ctx.fill();
ctx.closePath();
}
The following is multiple choice question (with options) to answer.
A person wants to play with a beach ball at the beach so they fill it with | [
"water",
"paper",
"gas",
"food"
] | C | a beach ball contains gas |
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