source string | id string | question string | options sequence | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-1 | nuclear-physics, astrophysics, sun, fusion, stellar-physics
Basically, the Sun is a ball of hydrogen and helium, but this is not all there is. Being a Population I star, the Sun contains heavier elements (called metals in stellar astrophysics; anything lithium and heavier is considered metal in this sense). These elements already came with the gas cloud the Sun has formed from, and were produced by previously burst older stars. Despite low abundance, the metallicity plays an important role in the Sun's core power stability.
At some depth the gas ball compresses its inner area enough to heat it up so much that hydrogen fusion into helium begins. This area is called the core. This is where practically all fusion happens, and what is responsible for the star's energy production. For a Sun-mass star and below, the proton-proton chain dominates. The pp-chain energy output is approximately proportional to $T^4$. The good news is, if reaction rate drops, then the outer layer of the star will compress the core, so it heats up, and the renewed energy output compensates for the compression. So this highly-sensitive dependency on the temperature is what gives the star its long term stability.
It is also notable that the center of the core is hotter and therefore more energetic than its periphery, and turns hydrogen into helium faster. Absent any mixing, the core would develop an inert helium ball in the middle (helium cannot be fused by a Sun-mass star, its core is too cold for that): A pp-chain core is entirely non-convective. However, there is another multistage reaction that fuses protons into helium nuclei, the CNO cycle. This cycle requires metals ($C$, $N$ and $O$, naturally) be present in the core. They are not consumed, but participate in stages of the reaction and are ultimately recycled. The rate of this reaction depends on the temperature as $T^{20}$. It's a huge dependency! The CNO-dominant core has so much temperature gradient that it's fully convective, so it mixes the material very thoroughly.
The following is multiple choice question (with options) to answer.
The sun is responsible for | [
"puppies learning new tricks",
"children growing up and getting old",
"flowers wilting in a vase",
"plants sprouting, blooming and wilting"
] | D | the sun is the source of energy for physical cycles on Earth |
OpenBookQA | OpenBookQA-2 | • mathscinotes says:
Hi Hanna,
Let's take a quick look and see if I am thinking of your problem correctly. To keep things very simple, let's assume that your theodolite is 100 m above the ocean and you are observing something in the water at a 45 °C angle. Using "flat Earth" methods, your subject is 100 m away -- correct? Let's work the same problem and determine the arc length of your subject from a point directly below your theodolite.
Here is my drawing that illustrates this situation.
I can convert this situation into a geometry problem as shown in the following figure.
I can analyze this geometry as shown below.
As you would expect, the arc distance is not much different than the distance you would compute using simple angles.
Is this what you were looking for? I can put it into Excel if you want to play with it.
Mathscinotes
• Mike says:
Why on a clear calm day can i take a perfect picture of chicago from lake mi.In michigan?200 plus miles straight across.
• Lance Collier says:
Lake Michigan is no 200 miles across, just 38 from Michigan City, IN to Chicago, yet bottom half of Willis (Sears) tower is cut off from view by the ~900ft of curvature at 38 miles. Only the tallest buildings in Chicago are visible at this distance.
• Jsw says:
The entire buildings are visible
• truth seeker says:
Yeah you can't fake the earth being a globe anymore. We are all waking up to it. I leave near the ocean, Have been a surfing photographer for over 35 years. I point my video camera on a clear day at the Santa Barbara Channel Islands from the beach and I can see the beach in front of the mountains. I can see the beach. Yet the island is 28 miles from shore and if the horizon drops 8" for every mile, then what I am looking at should be 20 ft below the horizon. How is it can see the sand on the beach? Because the earth is flat. Wake uP sheeple and you fake scientist that actually know the truth, your day is coming for this carrying on this lie.
• Mark says:
The following is multiple choice question (with options) to answer.
When standing miles away from Mount Rushmore | [
"the mountains seem very close",
"the mountains are boring",
"the mountains look the same as from up close",
"the mountains seem smaller than in photographs"
] | D | as distance to an object increases , that object will appear smaller |
OpenBookQA | OpenBookQA-3 | human-physiology, digestion, stomach
The stomach accomplishes much of its function by mechanically breaking down the swallowed food particles and mixing them with acid and enzymes into a sort of slurry. To do this, there are three major layers of muscle surround the stomach - from the outside, the longitudinal layer, the circular layer, and the oblique layer. The stomach also has two holes in it - the gastroesophageal opening, coming from the esophagus with the swallowed food/saliva mix, and the pylorus, where the food/acid/enzyme slurry exits into the duodenum, which is the beginning of the small intestine.
Due to the three layers of (rather strong) muscle, the stomach doesn't have a lot of expansion capability once it is filled completely to capacity. Fortunately, this almost never occurs (despite how we may feel after a large meal) because material is always leaving the stomach on its way to enzymatic digestion in the intestines. Additionally, once the stomach is filled to a certain extent, hormones such as leptin are secreted that give you the feeling of being sated, or full, triggering the brain to make you stop eating.
Of course, as we can see with the current epidemic of obesity around the world, the stomach can change its size over time. However, this is a rather slow process (weeks to months to years) of adapting to continuously consuming large meals.
But what would happen if you completely ignored these internal warnings, or were being force-fed, or whatever? Instead of rupturing (the biological equivalent of "exploding"), food would most likely be expelled either into the small intestine or back into the esophagus and back up the way it came down, i.e. causing vomiting.
The following is multiple choice question (with options) to answer.
When food is reduced in the stomach | [
"the mind needs time to digest",
"take a second to digest what I said",
"nutrients are being deconstructed",
"reader's digest is a body of works"
] | C | digestion is when stomach acid breaks down food |
OpenBookQA | OpenBookQA-4 | star, distances, betelgeuse
\hline
\text{HIP28202} & \text{7.97} & \text{60.42} \\
\hline
\text{HIP27919} & \text{7.15} & \text{60.85} \\
\hline
\text{HIP28056} & \text{7.17} & \text{60.89} \\
\hline
\text{HIP29381} & \text{8.88} & \text{61.26} \\
\hline
\text{HIP26986} & \text{9.17} & \text{61.26} \\
\hline
\text{HIP29630} & \text{8.15} & \text{62.56} \\
\hline
\text{HIP29590} & \text{7.82} & \text{64.37} \\
\hline
\text{HIP30120} & \text{6.76} & \text{64.57} \\
\hline
\text{HIP26795} & \text{6.82} & \text{66.03} \\
\hline
\text{HIP26655} & \text{7.09} & \text{66.99} \\
\hline
\text{HIP26615} & \text{9.13} & \text{67.50} \\
\hline
\text{HIP27895} & \text{7.04} & \text{68.80} \\
\hline
\text{HIP27309} & \text{9.7} & \text{69.04} \\
\hline
\text{HIP28323} & \text{8.16} & \text{69.12} \\
\hline
\text{HIP28171} & \text{8.68} & \text{69.91} \\
\hline
\text{HIP25767} & \text{8.93} & \text{70.26} \\
\hline
\text{HIP25698} & \text{8.74} & \text{70.31} \\
\hline
The following is multiple choice question (with options) to answer.
Stars are | [
"warm lights that float",
"made out of nitrate",
"great balls of gas burning billions of miles away",
"lights in the sky"
] | C | a star is made of gases |
OpenBookQA | OpenBookQA-5 | telescope, telescope-lens, diy
There's also an easier way. You could purchase a complete kit, like the Galileoscope:
http://galileoscope.org/
It's a 50 mm (2") f/10 refractor that has about the same performance like good binoculars. The price is very affordable (and very cheap for what it does). As a telescope and mirror maker, I was impressed by the quality of the achromat doublet objective that they provide (50 mm diameter, 500 mm focal length, f/10). For the price and the size, it is well made and well corrected, and punches well above its price category.
The kit comes with everything you need: all the lenses, the tube, various small parts, etc., including components for the ocular (eyepiece). Another nice thing is that you can swap its eyepiece for a standard 1-1/4" eyepiece used in a regular telescope (like a cheapie on Surplus Shed). Whoever designed this thing put some good thought in it. There are several different instruction documents on the site, that you can choose from.
My 9 and 12 year old sons put it together in an afternoon. It's that easy.
EDIT: What can you do with the Galileoscope?
Obviously, you can watch some of the planets. You'll see the two big equatorial belts on Jupiter, and the 4 galilean moons of Jupiter. Saturn's rings will be quite obvious. Venus will show a crescent - it will look just like the Moon, only much smaller.
You can watch the Moon, too. The big craters are quite visible in an instrument this size.
You can watch some of the deep space objects too. The Orion Nebula is quite visible actually. The Andromeda galaxy is somewhat visible from a place outside the city.
Double stars such as Albireo, which appear as single star to the naked eye, are easily split by a 50 mm aperture. Albireo is very pretty, and easy to see in a Galileoscope - an orange/blue double, easy and wide, very beautiful.
Mizar, one of the main stars in the Big Dipper, is also a double. This one is a lot more tight. I think you should be able to split it in a G-scope anyway.
http://www.synapses.co.uk/astro/bearings.html
The following is multiple choice question (with options) to answer.
You can make a telescope with a | [
"straw",
"Glass",
"Candle",
"mailing tube"
] | D | Galileo Galilei made improvements to the telescope to make better observations of celestial bodies |
OpenBookQA | OpenBookQA-6 | herpetology, poison
Title: Poisonous Snakes consuming poison (chemical) While travelling with my Son to a religious shrine, we saw a dead snake lying on the road.
My Son asked a curious question to me "Dad, if Poisonous snakes consume poison (Chemical), Will they die"?
I feel the answer is depends upon the type of poisonous snake viz Cobra, Python etc and how much the reptile has consumed the poison. i.e. quantity.
What is the correct answer? If any living thing consumes enough of a poison it will die. But I feel that is not what you want to ask.
Perhaps you meant to ask if a snake will die if it drinks its own venom? That would make more sense as a question.
In English, venom and poison mean different things when talking about a toxic chemical produced by an animal.
Poison is a toxic chemical produced by an animal that is meant to be ingested/eat/drink.
Venom is a toxic chemical produced by an animal that is meant to be injected into the bloodstream.
So a snake bite has venom, but a colourful tree frog has poison on its skin.
Venom is typically not nearly as harmful if ingested, even if by a different animal, because it is meant to act directly in the bloodstream
The following is multiple choice question (with options) to answer.
Poison causes harm to which of the following? | [
"a Tree",
"a robot",
"a house",
"a car"
] | A | poison causes harm to living things |
OpenBookQA | OpenBookQA-7 | genetics, mouse
Some researchers estimate that as many as 95% of CKCSs may have Chiari-like malformation (CM or CLM), the skull bone malformation believed to be a part of the cause of syringomyelia, and that more than 50% of cavaliers may have SM.* It is worldwide in scope and not limited to any country, breeding line, or kennel, and experts report that it is believed to be inherited in the cavalier King Charles spaniel. CM is so widespread in the cavalier that it may be an inherent part of the CKCS's breed standard.
(emphasis mine)
Same thing for that spine malformation that's related to selecting for corkscrew tails. The genes that make the tail corkscrew also mess with the spine.
In other words, the issue isn't inbreeding or not but whether the genes themselves are harmful. When organisms are selected for traits that are directly harmful in their extreme, or are associated with harmful genes that just happen to be next to those that are selected for in the chromosome, then the harmful consequences will spread through the population. Inbreeding is only a problem insofar as it allows the process go faster (more offspring per generation have the desired trait). On the other hand when you're just inbreeding with no specific focus on phenotype, or not phenotypes that have obvious harm associated (i.e. no lab would select for a frivolous trait that also causes harm. They're either selecting for the harmful trait on purpose, or they're selecting against it, because they'll want animals that are as healthy as possible except for the one variable they're interested in), then you'll end up with populations that are fairly normal except for some of the direct consequences of genetic uniformity.
It should be noted that most purebred dogs probably aren't inbred strains the same way many laboratory animals are; those are genetically identical, so the whole point is that their offspring will be like they are. So while they may be less fit than a non-inbred version of them might be, their offspring won't be any less fit than they are. And this is not what's observed with purebred animals like dogs and horses; individuals aren't identical, and looking at the page on Syringomyelia it seems the problems are getting worse.
The following is multiple choice question (with options) to answer.
an inherited characteristic found on all mammals is | [
"nails",
"teeth",
"shoes",
"fur"
] | D | the colors of the parts of an organism are inherited characteristics |
OpenBookQA | OpenBookQA-8 | biochemistry
Title: Bradford Reagent Disposal I am a graduate student volunteering in a professor's lab being tasked with finding out how to dispose of certain hazardous materials. I have encountered a problem with disposing of Bradford's Reagent. I have checked online, but am running into problems due to the methanol component of this compound. Can someone help me with the proper disposal procedure? Thank you in advance. I would strongly suggest to ask someone in your lab about this, they will have a better idea about the different waste disposal methods you have available.
In general you would dispose anything that contains organic solvents like methanol in a waste container for generic solvent waste. You should have something like that somewhere in the lab.
One thing you always have to keep in mind is to never put anything still reactive into your waste container. A popular example would be a strong oxidizing agent, putting that into a solvent waste container is dangerous and could e.g. ignite the waste. This is not an issue in this case, but you should always keep that in mind.
Another aspect is the pH of the waste, in many cases the waste disposal facility will only accept reasonably neutral waste, so you should neutralize your waste before putting it into a container. Neutralizing it inside the container can be much more annoying. This might not be necessary if you have a dedicated acidic waste, you'll have to ask someone in your lab about that. The Bradford reagent is strongly acidic, so you'll have to pay attention to this aspect.
The following is multiple choice question (with options) to answer.
What doesn't eliminate waste? | [
"plants",
"mushrooms",
"bacteria",
"robots"
] | D | all living things eliminate waste |
OpenBookQA | OpenBookQA-9 | visible-light, electromagnetic-radiation, speed-of-light, everyday-life, atmospheric-science
If the blocking occurred close to the sun, you would see the opening of the blocking ca. 8 minutes after it happened, but you would also feel it 8 min after it happened. Thus you would experience both at the same time.
An analogy:
Imagine a car standing at a tunnel entrance that is blocked. You are standing at the opposite end of the tunnel. Now the road is opened and the car drives through the tunnel towards you. The car reaches you ("warmth") at the same moment that you receive the information that the tunnel is not blocked anymore. It does not matter how long the tunnel is or how fast the car is driving.
The following is multiple choice question (with options) to answer.
As a car approaches you in the night | [
"the headlights become more intense",
"the headlights recede into the dark",
"the headlights remain at a constant",
"the headlights turn off"
] | A | as a source of light becomes closer , that source will appear brighter |
OpenBookQA | OpenBookQA-10 | 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.
When the weather changes as it does from Christmas to Easter, | [
"the air may chill",
"the ground may freeze",
"the plants may die",
"the ground may warm"
] | D | seasons cause change to the environment |
OpenBookQA | OpenBookQA-11 | energy, sun, stars
Then figure that cooking meat with sunlight does require at least some sort of magnifier, so we can probably multiply that by a factor of at least 3, and probably more like 7-10 or so.
Of course, for now I'm ignoring a such minor details as how you even design (not to mention building) a system even close to that size. There would be decidedly non-trivial challenges involved. For example, the largest mirrors we've built yet have diameters around 10 meters (or non-round mirrors of roughly equivalent area). These are already built in sections, with a computer to control movement of the individual pieces to maintain the illusion of a single mirror acting as a unit. Trying to multiply that out to multiple kilometers--well, I don't think anybody's even contemplated what that would take yet.
The following is multiple choice question (with options) to answer.
Using mirrors to focus collected light from heavenly bodies allows | [
"detailed observation",
"foregone conclusions",
"radiation experiments",
"celestial music"
] | A | detailed observation of celestial objects requires a telescope |
OpenBookQA | OpenBookQA-12 | metabolism, ecology, photosynthesis
Title: Why isn't phosphorus or nitrogen a limiting nutrient for animals? Nitrogen and Phosphorus are usually the limiting nutrient for plants, especially for algae. Phosphorus is used for DNA, ATP and phospholipids, and Nitrogen is used for pretty much every protein a cell might want to produce. That is, their need for biological processes is not tied specifically to photosynthesis: anything that lives is going to need them, pretty much for anything it might want to do. It would make sense for them to be a limiting nutrient for almost anything that's trying to grow, plant or animal.
Yet for animals the limiting "nutrient" seems to always be energy, ie: food. Why aren't animals limited by lack of nutrients in the same way that plants are? Obviously animals need these nutrients, too. Or to reverse the question, why do plants need so much more phosphorus/nitrogen than animals do?
My best guess is that an animal's digestion of plant material is relatively inefficient energy-wise but relatively efficient nutrient-wise. So for an animal to eat enough food to have sufficient energy to survive, it's probably eaten more than enough Nitrogen and Phosphorus for its needs. But I'm just guessing and I can't find any data that would back up that guess. Phosphorus
Your suggestion that if we are meeting our calorific requirement we will be getting enough is true for phosphorus.
Most foods contain lots of phosphorus. The maximum dietary requirement occurs during adolescent growth, estimated at 1250 mg per day. Assuming a calorie intake of 2500 kcal we can calculate a 2500 kcal equivalent phosphorus content for various foods:
skimmed milk contains 7,400 mg phosphorus per 2500 kcal
roasted chicken breast contains 7,500 mg phosphorus per 2500 kcal
cooked white rice contains 3840 mg per 2500 kcal
(Calculations are based upon values obtained via this site.)
Nitrogen
Our requirement for nitrogen is met by our protein intake: inadequate protein intake manifests as kwashiorkor which is essentially due to a dietary deficiency of essential amino acids. In other words, the only way to achieve a nitrogen-deficient diet is to not eat protein, and this would not be alleviated by any inorganic source of nitrogen, even if we could consume enough of such a N source.
The following is multiple choice question (with options) to answer.
Which of these things will supplement a squirrel's caloric needs? | [
"fish",
"tree bark",
"nuts",
"leaves"
] | C | an animal needs to eat food for nutrients |
OpenBookQA | OpenBookQA-13 | visible-light
Here is an image to help you visualize. The black rectangle on the bottom-middle is the tube, with its width = $a$ and height = $L$, the blue lines represent the line of sight, the orange lines are the areas (at different distances) that contribute light to the sensor. Keep in mind that this is a 2d representation of a 3d system, this is why in the image the closest orange line has length of $3a$, which translates to an area of $(3a)^2 = 9a^a$ (like I said above). Same goes for the rest of the orange lines.
To put this into perspective (generously) if $L=100m$, and $a=0.1mm$ looking at the moon each sensor will collect light from an area of more than $5\cdot 10^5m^2$. The overlapping of the areas, each sensor collects, would be awful. You would probably see just a smudge. At this point multiple tubes are just pointless, as you would need an array of ridiculous size for the sensors that are furthest away to collect anything meaningfully different.
Looking at Alpha Centauri A (The largest star in the nearest star system, other than the Sun) each sensor will collect light from more than $5\cdot 10^{21} m^2$. That is orders of magnitude larger than the star's area.
You can see why such a devise fails, even looking at relatively close objects.
The following is multiple choice question (with options) to answer.
As you look deeper into a Marbel you can see | [
"the future",
"minut defects",
"colors",
"the other side"
] | B | as the size of an object appears larger , that object will be observed better |
OpenBookQA | OpenBookQA-14 | toxicity
Title: Would standing next to a pool of mercury do you any harm? I was watching this clip from the 2017 film The Mummy in which the characters stand next to a pool of mercury which was being used as part of an elaborate prison.
Several comments under this video imagine that standing next to a pool of mercury would be very dangerous, but I can't see any reason to think that a significant amount of vapour would be coming from the pool so it seems like the mercury just being there in liquid form would be quite harmless. But maybe I shouldn't go robbing any graves any time soon.
The automatic warning dialogue told me the question appears quite subjective. So, let's say you're standing next to the pool for no more than ten minutes and we'll define harm as requiring medical intervention or (if chronic) as having a demonstrable, long-term health effect, such as erethism. I have no idea how large the pool is in the video, but for the purposes of the question, we'll say it's a circular pool of 10 metres in diameter. It depends. But there is little short term risk.
Mercury metal isn't very toxic. You can even ingest it without significant short or long term effects. But mercury vapour is nasty and you don't want to be continuously exposed to any significant amount of that (see this answer for more detail). And some mercury compounds are pretty nasty too.
Of course mercury metal emits mercury vapour so there will always be some in any room with exposed mercury. But the reason why this isn't an immediate worry is that it takes time to absorb enough vapour for it to become notably toxic. Chemists are used to handling liquid mercury in the open lab but are a lot less comfortable if it has been spilled and not cleaned up. This didn't used to be so which is one of the reasons we know the dangers: chemists who were exposed to vapour over years did suffer toxic effects. Mercury miners suffered similar long term toxic effects from the vapour. In modern labs we make sure the vapour doesn't build up by good ventilation and making sure any spills are cleaned up quickly so exposed mercury doesn't hang around emitting vapour.
The following is multiple choice question (with options) to answer.
What happens when mercury is placed in water? | [
"it dissolves",
"it sinks",
"it floats",
"it hardens"
] | B | a body of water is a source of water |
OpenBookQA | OpenBookQA-15 | species-identification, entomology
Title: Please help to identify this insect It is approx 1.5 inch (3 cm to 4.5 cm) long
The insect's back and wings.
Insect from its forward side
Just few hours ago (around night 10 to 10.30 pm local time), this insect entered into our home, flying in high-speed and hitting to wall, objects, and to us. To keep it calm we turned the room-light off. Then it became steady on my father's shirt even after the light again turned on, and it was a beautiful moth-like insect. After taking photo it gently freed out of the room.
Here in India, it is rainy season (after summer).
P.S. I've very very little-experience in practical-zoology, however after few hours google search it seems to match with those moths tagged as "hawk-moths", and another notable feature when it was flying it looked like a hummingbird or a small bird, that was written in the description of some "hawk-moths" in different sites. Initially we're taking time to decide whether it is an insect or a bird. As MattDMo suggested, this is a hawk moth. Given your location and season, this is why I thought it was either the Impatiens hawkmoth (Theretra oldenlandiae) or the White-edged hunter hawkmoth (Theretra lycetus). And finally, why I now think it is the Brown-Banded Hunter (Theretra silhetensis).
Brown-Banded Hunter Hawkmoth
The Theretra silhetensis exhibits a solid white line along the upperside of its abdomen, and more of a faded banding pattern on the forethat corresponds with your picture. These moths are also common in India.
It is differs from T. oldenlandiae in being very much paler in color
and with white line down center of abdomen.
When it comes down to it, that solid single white line is the biggest indicator it is a T. silhetensis over a T. oldenlandiae or T. lycetus.
The following is multiple choice question (with options) to answer.
In the desert, a hawk may enjoy an occasional | [
"coyote",
"reptile",
"bat",
"scorpion"
] | B | hawks eat lizards |
OpenBookQA | OpenBookQA-16 | electromagnetism, magnetic-fields, everyday-life
Title: How is magnetism ''conducted'' through a non-magnetic metal? I have a ball of metal about an inch in diameter and a concave disc of another metal (which is magnetic) around the ring of the disc (about $12 {\rm mm}$ in diameter). I don't know which metals they are. The ball is not magnetic on its own. That is paramagnetism, right?
The magnetic ring is strongly attracted to the surface of the ball, 'sticking' to it. However, I can stick a paperclip on the opposite side of the ball as if it has become magnetic itself, until I remove the magnetic ring from the ball.
When I wave the paperclip the same distance from only the ring itself, I feel no force at that distance.
Has the strong magnetic field of the ring caused a temporary magnetic alignment through the metal of the ball, allowing the paperclip to be attracted to it while the ring remains? The phenomenon you describe is ferromagnetism not paramagnetism.
Ferromagnetic materials like iron behave as if they contain many tiny bar magnets (called magnetic domains if you're interested to pursue this further), but because the magnet domains are aligned randomly the fields cancel out and there is no net magnetic field.
However if you put a ferromagnetic material in a magnetic field the external field will cause partial alignment of the magnetic domains. This induces a magnetic field in the originally unmagnetised iron, and that's why your paper clip sticks to the ball. However if you remove the external magnetic field the domains will go back to their original alignment, the net magnetic field will go back to zero and the paper clip will fall off again.
If you apply a very strong field and/or combine it with heating and cooling you can permanently change the alignment of the magnetic domains so they remain aligned when the external field is removed. This is how you make permanent magnets.
The following is multiple choice question (with options) to answer.
A magnet will stick to | [
"a belt buckle",
"a wooden table",
"a plastic cup",
"a paper plate"
] | A | a magnet attracts magnetic metals through magnetism |
OpenBookQA | OpenBookQA-17 | the-sun, light, rotation, planetary-atmosphere
Title: Why is twilight longer in summer than winter and shortest at the equinox I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with that all year.
While doing some research for this, I noticed something that surprised me. Check out this disparity between astronomical sunrise to civil sunrise for the solstices and equinox (the latter two adjusted for daylight saving time):
Date/Astronomical/Civil/Disparity
Dec 20: 0533 - 0640 (67 minutes)
Mar 20: 0526 - 0630 (64 minutes)
Jun 20: 0320 - 0451 (91 minutes)
To be honest, these sets of ranges surprise me for multiple reasons. I clearly don't know what I don't know, but here are some questions I can formulate:
Why would twilight be longer in summer than winter? Before seeing this data, I had assumed that since the sun makes a more perpendicular path through the horizon in summer that twilight would be shorter in summer than in winter. After all, in winter the sun takes a "slanted" path across the horizon. Wouldn't the summer's path be more direct and therefore quicker?
OK: seeing this empirical evidence I conclude that something is wrong with my premise that forms my first question. Summer twilight is longer in summer than winter. However, I still would have assumed that March 20 would have had a twilight length in between the two solstices. But it's not! Why does the equinox have the shortest twilight?
Appended 5/13/2014:
I didn't want to leave my original incorrect statement in here without flagging it. As Cheekhu points out below, the sun does not follow a more perpendicular path in summer than winter, as I had erroneously assumed and stated above. See his post for more details. See this diagram,
The following is multiple choice question (with options) to answer.
Shorter periods of daylight happen | [
"October to December",
"November to March",
"December to April",
"December to March"
] | D | the amount of daylight is least in the winter |
OpenBookQA | OpenBookQA-18 | c++, game
outfile << "Room:" << endl;
outfile << "5 2" << endl;
outfile << "country_10" << endl;
outfile << "You are in the countryside, to the north is the road & to the south is a large hill." << endl;
outfile << "null" << endl;
outfile << "Maybe go back to the road?" << endl;
outfile << "0" << endl;
outfile << "Room:" << endl;
outfile << "5 3" << endl;
outfile << "hill" << endl;
outfile << "After a brisk climb to the top of the hill, you finally look around you. On the top of the hill is a tall oak tree, providing much needed shade from the summer heat. From the tree you can see a town to the north-east and a hut to the south-east. There is also a path leading to the hut from the road, it passes by right at the foot of the hill." << endl;
outfile << "null" << endl;
outfile << "Head for the town" << endl;
outfile << "0" << endl;
outfile << "Room:" << endl;
outfile << "5 4" << endl;
outfile << "country_7" << endl;
outfile << "You are in the countryside, to the north is a large hill." << endl;
outfile << "null" << endl;
outfile << "Maybe go back to the road?" << endl;
outfile << "0" << endl;
The following is multiple choice question (with options) to answer.
A person is lost in a dense forest, and needs to find their home. They know their home is to the south, and they are headed north. They can find home by using a | [
"northern-directing device",
"northern light reader",
"northeastern winds",
"north central credit"
] | A | a compass is a kind of tool for determining direction by pointing north |
OpenBookQA | OpenBookQA-19 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
Where are you likely to find a nonrenewable resource? | [
"a forest",
"a dam",
"a mine",
"a solar panel"
] | C | natural gas is a nonrenewable resource |
OpenBookQA | OpenBookQA-20 | arduino, wheeled-robot, algorithm
Title: How to find the height of a rock with a rover? So, I am designing a rover that will navigate to a rock, and then calculate the height of the rock. Currently, my team's design involves using an ultrasonic rangefinder and lots of math. I was interested in what sensors you would use to solve this problem, or how you would go about it? Assume that the rover has already located the rock.
Additional Info: We are using an Arduino Uno to control our rover. It is completely autonomous. Given the scales we are talking about I think the lumberjack technique would not work. Lumberjacks walk away from a tree until they visually measure an angle of 45 degrees between the bottom and the top of the tree: at that point they are standing at a distance from the tree which is equal to its height, and which they can measure easily walking back to the tree. It only works because the lumberjack is small in comparison to the tree so model approximations such as "the eyes of the lumberjack are at ground level" or "the ground is perfectly horizontal" hold true enough to not impact the final result too much. I don't think it would work well enough on a rover and a 7" rock. Note that if you wanted to go this route anyway you could implement it with a camera or a laser rangefinder, and you could use any angle and trigonometry formulas.
Because the rock is small I would use a mechanical trick. Maybe use a pole with a sonar pointing down that you would place directly above the rock. You could use a pendulum to make sure it's vertical even if the rover is on uneven ground. Or you could develop a device like a forklift that you would place above the rock and progressively lower until you hit the rock. You would then know the height based on the position of the stepper/servo driving the lifting part.
That's the way I would go with this challenge, I encourage others to post their answers if they have different ideas because there might be plenty of other interesting solutions!
The following is multiple choice question (with options) to answer.
A man is searching for his dog in the woods and brings a flashlight. The flashlight has two large batteries in it, which | [
"provide light due to wiring",
"provide light through plastic",
"use light to heat the flashlight",
"provide light due to moisture"
] | A | a flashlight converts chemical energy into light energy |
OpenBookQA | OpenBookQA-21 | the-sun
2460163.500000000, A.D. 2023-Aug-07 00:00:00.0000, 6.625425330791064E-02, 3.556004033547897E+05, 5.050458943166362E+00, 2.761268189373863E+01, 2.787078308606339E+02, 2.460158097611625E+06, 1.548623091365481E-04, 7.228451565776196E+01, 7.968276040122535E+01, 3.808321533078448E+05, 4.060639032608998E+05, 2.324645693372517E+06,
2460164.500000000, A.D. 2023-Aug-08 00:00:00.0000, 6.507275768816487E-02, 3.554955131298805E+05, 5.053938392861703E+00, 2.761547227317707E+01, 2.775232172597620E+02, 2.460158014454506E+06, 1.552250039753550E-04, 8.698050648988226E+01, 9.443786013757804E+01, 3.802386934953690E+05, 4.049818738608575E+05, 2.319213984733781E+06,
$$EOE
The following is multiple choice question (with options) to answer.
the summer solstice is on June 21st in the | [
"in the south pacific",
"upper portion of earth",
"lower portion of earth",
"the equator near the tropics"
] | B | the summer solstice is on June 21st in the northern hemisphere |
OpenBookQA | OpenBookQA-22 | ## 35.
The Correct Answer is (1/29) — The probability of choosing one student wanting to enter finance is 6/30. The probability of choosing another student wanting to enter finance is then 5/29. The probability of both of these events occurring is therefore (6/30)(5/29) = 30/870, which can be reduced to 1/29.
## 36.
The Correct Answer is (40) — Since the small triangle and the entire triangle share two angles (the one on the right, and the right angle), they must share all three angles, and therefore are similar triangles. You can use the Pythagorean Theorem on the bigger triangle to find that the length of the horizontal side is the square root of 1002 - 602, which is 80. (This is a special 3-4-5 triangle with the side lengths multiplied by 20). Since the ratio of the vertical side to the horizontal side of the big triangle is 60/80 = 3/4, this must be the same as the corresponding ratio in the small triangle. Since the vertical side has length 30, the length marked x must have length 40.
## 37.
The Correct Answer is (10) — There are 6 full cages of mice, which means there are 6 × 5 = 30 mice. If we let n be the number of male mice, then the number of female mice is twice that at 2n. There are 30 mice in total, so n + 2n = 30. Solving for n gives you n = 10. Since n is the number of male mice, there are 10 male mice.
## 38.
The Correct Answer is (17) — The reduced cost of maintaining each cage is 0.5($1.25) =$0.625 per cage per day. The student needs 21 cages to house 102 mice, so her daily cost is $0.625 × 21 =$13.125. She has a budget of $225, so she can afford to maintain the cages for$225/\$13.215 = 17.14 days. Rounding this to the nearest whole day gives you 17 days.
The following is multiple choice question (with options) to answer.
A mouse is being hunted by a Great Horned Owl. The owl watches the mouse carefully, and the mouse is unaware that it is being hunted. The mouse is unable to tell where the owl is, because | [
"the owl is invisible",
"the mouse is oblivious",
"the mouse is blind",
"the owl matches its background"
] | D | camouflage is used for hiding by animals from predators |
OpenBookQA | OpenBookQA-23 | 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.
You would use a seismometer if | [
"A mysterious rumble off the coast of Japan",
"Someone farted in class",
"Kids were stomping on the floor",
"to track the buzz of a bee"
] | A | a seismometer is used to measure the strength or magnitude of an earthquake |
OpenBookQA | OpenBookQA-24 | reproduction
Title: Why are so many species reproducing late this year? Hope this question is OK for this site, couldn't see where else to ask it.
We've spent a few days out in the countryside recently, and have been very surprised at how many species appear to have very young offspring so late in the season. I was always under the impression that the vast majority of animals and fish produced young in the spring (March/April).
For example, we saw tadpoles, fluffy (ie obviously very young) coots and weeny minnows. I would have expected that all of these would have been born/laid a good 3 or 4 months ago, and so would be more mature by now.
Caveat: We didn't do a scientific study, this is just a strong impression we got from days out in north west England. It's hard to say without more information, but one substantial possibility is that you are mistaken that species are reproducing late - that's a problem with anecdotal rather than scientific data!
Additionally, species you mention like the common coot can attempt multiple broods where the season is long enough. Wikipedia specifically mentions Britain:
Eurasian coots normally only have a single brood each year but in some areas such as Britain they will sometimes attempt a second brood
The same could be true for species of frogs/toads and fish, so without knowing specific species it can't be known whether these are species reproducing again or species reproducing late.
The following is multiple choice question (with options) to answer.
Many animals that give birth to live young have | [
"gills",
"scales",
"exoskeletons",
"legs"
] | D | mammals give birth to live young |
OpenBookQA | OpenBookQA-25 | theoretical-biology, hematology, red-blood-cell
**As an intern, I once had the very sorrowful experience of admitting an healthy appearing, exuberant 4 year old child to the pediatric surgical service. The only presenting symptom was that the child started squatting during exertion (not good), and on exam, had a murmur which was caused by aortic stenosis. This was long before imaging studies were as sophisticated as they are now. The pediatric cardiac surgeon took him to the operating room (OR) to replace the valve, but there was so much atherosclerotic aortic damage that there was no healthy tissue which could hold sutures in place. The child died in the OR. I don't know what would have been done today, but had the child stayed home, they might have had a couple more years with the parents, who hoped for an uneventful procedure. So the exercise involved in this answer was fun, but the memory it brought back is still quite sad.
The following is multiple choice question (with options) to answer.
A child will only grow if they are provided with | [
"a bed",
"education",
"inspiration",
"energy"
] | D | an organism requires energy for growth |
OpenBookQA | OpenBookQA-26 | oceanography, sea-level, tides
Title: Why do high tides vary month to month? I've noticed that some ‘highest‘ high tides in one month are bigger than the highest high-tide of previous months. Why is this so? The dynamics of the tides are quite complex. The main idea is that gravity from the Moon and the Sun affect water (and everything else) on Earth. The issue is that there are several motions that alter the distance between the 3 systems and those motions cause interactions between the different frequencies involved. The Equilibrium Theory of Tides separates the different effects into a set of constituents by conducting a harmonic analysis. The relevant periods are:
the lunar day (period of lunar rotation), 24.84 mean solar hours.
the sidereal month (period of lunar declination), 27.32 mean solar days.
the tropical year (period of solar declination), 365.24 mean solar days.
the period of the lunar perigee, 8.85 years (1 year = 365.2421988 days).
the period of the lunar node, 18.61 years.
the period of the solar perihelion, 20940 years.
The explanation of each constituent can be rather complex (some examples in this other answer). The different amplitudes in a day and the spring-neap cycle are related to the combination of the main lunar and solar effects.
The differences in high/low tide from month to month are related to the next two main frequencies of oscillation. Mainly, the variations in Earth-Sun distance associated occurring in a period of tropical year. The lunar distance also contributes to these differences, but its cycle is much longer (~9 years). Also, the spring-neap cycle (with a frequency of half a lunar month ~13.5 days) will occur at different times of the month and can lead to differences in tidal amplitude if you compare the tides measured the same day of consecutive months.
(Source www.niwa.co.nz)
The following is multiple choice question (with options) to answer.
Every twenty-four hours and fifty minutes, the moon can have an effect on bodies of water causing them to | [
"swell",
"float",
"die",
"burn"
] | A | high tide is a stage in the tide cycle process |
OpenBookQA | OpenBookQA-27 | ecology
Title: Statement about Tropical Rainforests I made a statement about tropical rainforests, and I want to know if it's somewhat true or not:
The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The reason that a tropical rainforest has a huge amount of vegetation is because of the quick mineralisation. If a dead leaf falls onto the ground, it immediately gets turned into minerals, which the plants immediately use for sustaining theirselves There are many websites which describe this phenomenon. They all seem to confirm the basic premise of the question: in tropical rain forests most of the minerals are held in the biomass and rapid decomposition contributes to the recycling of these nutrients for new growth. One example is here.
Tropical rainforests are noted for the rapid nutrient cycling that occurs on the ground. In the tropics, leaves fall and decompose rapidly. The roots of the trees are on the surface of the soil, and form a thick mat which absorbs the nutrients before they reach the soil (or before the rain can carry them away). The presence of roots on the surface is a common phenomenon in all mature forests; trees that come along later in succession win out in competition for nutrients by placing their roots over top of the competitors, and this pattern is seen in the temperate rainforest as well. What does not occur in the temperate rainforest, however, is a rapid cycling of nutrients. Because of the cold conditions and the acidity released by decomposing coniferous needles on the forest floor, decomposition is much slower. More of the nutrients are found in the soil here than would be the case in a tropical forest, although like the tropical forest most of the nutrients are held in the plants and animals themselves.
I looked for actual evidence of these differences in rates of decomposition and I found this:
Salinas, N. et al. (2011) The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests. New Phytologist 189: 967-977
The following is multiple choice question (with options) to answer.
The many trees on a forest floor | [
"are unable to decay",
"are able to regrow themselves",
"are broken down for good",
"broke, passed, will decay"
] | D | if a tree falls then that tree is dead |
OpenBookQA | OpenBookQA-28 | newtonian-mechanics, friction, aerodynamics, speed
Title: Is possible to use the air friction to increase the speed of a car? Its possible to make a device that, attached to the car, it will use the air that hits the car at high speed and give the car a boost? Friction wants to resist relative movement between the air and the car. If the air is not moving forward relative to the direction your car is moving, the friction cannot be used to increase the speed.
If the wind were blowing in the same direction you wanted to travel, and faster than you wanted to travel, then yes, friction could speed up your car up until it reaches the wind speed. This would basically be using your car as a sail to assist it's movement.
You won't have much luck using the "hitting" of the air to help power your car though if you're traveling against the wind. The air would have momentum on the other direction that you are trying to generate momentum; so they do not constructively add; but instead combat each other.
The following is multiple choice question (with options) to answer.
A car is driving on a highway trying to get up the the speed limit. However, there are strong winds hitting the windshield of the car. Even though the driver is trying to speed up, the high winds | [
"flip the car over",
"help the car go faster",
"conflict with the driver's goal",
"move the car sideways"
] | C | a force acting on an object in the opposite direction that the object is moving can cause that object 's speed to decrease in a forward motion |
OpenBookQA | OpenBookQA-29 | 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.
a student leaves a nail line on a mineral sample, so that mineral can be described as what? | [
"a mineral",
"a soft mineral",
"a liquid mineral",
"a mineral melt"
] | B | if a mineral can be scratched by a fingernail then that mineral is soft |
OpenBookQA | OpenBookQA-30 | physical-chemistry, acid-base, equilibrium
*There is perhaps some subtlety here. As an example, consider the salt $\ce{MX}$, which dissociates weakly into $\ce{M+}$ and $\ce{X-}$. The intuition behind the greater degree of dissociation is that (1) upon dilution, the equilibrium constant for dissociation doesn't change, whereas (2) the concentration of each species decreases. Because dissociation produces more ions than was originally present, this always leads to $Q < K$, and more dissociation will occur.
If we add a salt $\ce{MY}$, then, we are introducing two effects: (1) decreased concentration of $\ce{X-}$ and (2) increased concentration of $\ce{M+}$. Because these effects pull the equilibrium in opposite directions, we can't conclusively determine what exactly will happen. Going back to your example, if we add a slightly stronger base, then we get exactly these two contrasting effects, and the change in the degree of dissociation is indeterminate. In contrast, if we add a much stronger base, then certainly (2) dominates and the degree of dissociation is reduced.
The following is multiple choice question (with options) to answer.
An example of a chemical change is acid breaking down substances, another is | [
"flour added to salt",
"milk added to water",
"corn added to soup",
"lemon juice added to milk"
] | D | An example of a chemical change is acid breaking down substances |
OpenBookQA | OpenBookQA-31 | mixtures, gas-phase-chemistry
Now as it happens, for ideal gases, which the atmosphere is close to being, you can mentally subdivide the volume into tiny little equal-sized cubes, one for each atom or molecule in the mixture, and on average there would be one atom/molecule of $X$ in each fourth cube if $X$ is 25% by volume of the mixture. (I emphasize "on average" because of course since the gas atoms or molecules are continuously moving around randomly, they will bunch up and spread out momentarily all the time, so at any given instant there may be zero or many more than one $X$ atom/molecule per tiny cube.) Real mixtures in the liquid state often have at least some nonideality, e.g. even in a dilute solution of $\ce{NaCl}$ in water, you will find "structure" in the solution, with the $\ce{Na+}$ cations and $\ce{Cl-}$ anions surrounded by a fairly fixed arrangement of $\ce{H2O}$ molecules, almost like a tiny piece of clathrate, so a mental arrangement of tiny boxes is an even less accurate atomic-scale description of the solution.
In short, the percent by volume description of a mixture is only a way to characterize the amount of material that goes into it, it is not intended as any kind of implication of what the mixture looks like at the atomic scale.
As for why NASA reports the composition of the atmosphere by percent by volume: probably because it's closest to the actual experiments done to measure it. You would typically measure the composition of a gas mixture by physically separating it (e.g. by lowering the temperature until each gas liquefied) and then measuring the volume of each component. You certainly could from those measurements easily calculate a percent by moles, but – why? You introduce a calculational step between the measurement and what you report, and scientists tend to prefer getting original data, right what comes from the instrument, if possible, as a way of avoiding even the smallest risk of some error introduced in calculation.
The following is multiple choice question (with options) to answer.
Matter in the gas phase has | [
"fluctuating volume",
"turned up volume",
"turned down volume",
"steady volume"
] | A | Matter in the gas phase has variable volume |
OpenBookQA | OpenBookQA-32 | electromagnetism, momentum, conservation-laws, classical-electrodynamics
There is a very nice example of all this, worked out concretely, in these notes.
The following is multiple choice question (with options) to answer.
an example of an excellent earth mover is | [
"cat",
"dog",
"annelids",
"fish"
] | C | earthworms create tunnels in soil |
OpenBookQA | OpenBookQA-33 | reproduction
Title: Why are so many species reproducing late this year? Hope this question is OK for this site, couldn't see where else to ask it.
We've spent a few days out in the countryside recently, and have been very surprised at how many species appear to have very young offspring so late in the season. I was always under the impression that the vast majority of animals and fish produced young in the spring (March/April).
For example, we saw tadpoles, fluffy (ie obviously very young) coots and weeny minnows. I would have expected that all of these would have been born/laid a good 3 or 4 months ago, and so would be more mature by now.
Caveat: We didn't do a scientific study, this is just a strong impression we got from days out in north west England. It's hard to say without more information, but one substantial possibility is that you are mistaken that species are reproducing late - that's a problem with anecdotal rather than scientific data!
Additionally, species you mention like the common coot can attempt multiple broods where the season is long enough. Wikipedia specifically mentions Britain:
Eurasian coots normally only have a single brood each year but in some areas such as Britain they will sometimes attempt a second brood
The same could be true for species of frogs/toads and fish, so without knowing specific species it can't be known whether these are species reproducing again or species reproducing late.
The following is multiple choice question (with options) to answer.
Which animal gives birth to live young? | [
"Shark",
"Turtle",
"Giraffe",
"Spider"
] | C | mammals give birth to live young |
OpenBookQA | OpenBookQA-34 | botany, plant-physiology
Title: Can any plant regenerate missing tissue? I have not yet found a plant that, when an insect eats a hole in one of its leaves, it can regenerate the lost tissue. Many plants will grow a new stem if the old one is cut, but it is not a perfect regeneration, and has no likeness in form to the previous stem. Are there any plants that can, even to a degree, regenerate missing tissue? In general, plant cells only undergo differentiation at special regions in the plant known as meristems. Two of the primary types of meristem are the root apical meristem (at the tips of roots) and the shoot apical meristem (at shoot tips)^. Within the shoot apical meristem the plant cells divide and begin to differentiate into different cell types (such as different cells of the leaf, or vascular cells). Later growth (of, say, a leaf) is largely a result of cell expansion (although cell division does still occur, but drops off as the leaf expands). Therefore, if you punch a hole in a leaf, it probably won't be filled in because the cells in that leaf have finished growing and dividing.
However, as a shoot grows, more meristems are created. These are found in the axillary buds, just above where the leaf meets the stem. The meristems in the axillary buds can grow to form branches. Different plants obviously make different numbers of branches, but there is a common control mechanism known as apical dominance, where the meristem at the tip of the shoot suppresses the growth of the lower axillary buds. This is why a shoot with no branches can be made to grow branches by cutting off the tip (gardeners often do this to make "leggy" plants more bushy).
All of that was a long explanation to say, no, a plant doesn't normally^^ regenerate in the sense of filling in cells that have gone missing. However, if you cut off a shoot, the next remaining bud might begin to grow and, in a sense, replace the part that was lost. In that case, an existing bud is recruited to form a new branch and replace lost functionality, but I wouldn't say that qualifies as regenerating missing tissue.
^There are other types of meristem as well.
The following is multiple choice question (with options) to answer.
As a plant's roots get bigger, they split apart | [
"worms",
"water",
"granite",
"atoms"
] | C | a plant 's roots slowly break down rocks as the roots grow |
OpenBookQA | OpenBookQA-35 | star, galaxy
If you're on a farm, away from cities, in a place with reasonably low light pollution, and your eyes are good, and you've been sitting in perfect pitch black darkness for at least 30 minutes prior - when you look up you can reasonably expect to see a few thousand objects, mostly stars. Keep looking, and after a while you will distinguish one or two thousand more stars, very faint, that you could not see at first sight. Practice this steadily for a few years, and you'll add maybe another thousand; but you won't be able to see those all at once - only one at a time.
Now travel to the Cerro Tololo site in Chile, up in the mountaineous desert, zero light pollution, excellent transparency, and you'll multiply all those numbers by a factor of 2x ... 5x.
As you can see, the numbers are very flexible because there are so many factors involved. You can't just slap a 44k label on it and call it a day; that doesn't make any sense in reality. Astronomers know that the pure magnitude number doesn't mean much by itself, because it is just one factor among many.
In a place with very high light pollution (like where I live, in the middle of a large, dense, sprawling urban area in California), you'd be lucky if you can see a hundred stars at night.
Or, in a place with zero light pollution, shine a flashlight into someone's face, and you've temporarily blinded them. You've reduced the number of stars they could see by an order of magnitude for the next half hour (night vision gradually recovers, and it takes 30 minutes to fully recover, according to US military manuals and visual astronomers practice).
The following is multiple choice question (with options) to answer.
In the wilderness, light pollution is? | [
"less",
"stronger",
"brighter",
"more widespread"
] | A | as distance to a city decreases , the amount of light pollution will increase |
OpenBookQA | OpenBookQA-36 | optics, water, evaporation, gas
Title: How are water vapors not visible? This site says that water vapor isn't visible.
However, take a look at this picture:
Isn't that water vapor? Water vapour is a clear and colourless gas, so it can't be seen by the naked eye.
What you see in the photo in your second link is (partially) condensed water vapour, i.e. fog (or mist). Fog contains tiny, discrete water droplets and light bounces off their surface in random directions, causing the visibility.
Water vapour by contrast only contain free molecules, too small for light to bounce off, so pure water vapour (without any condensate) is invisible, like most gases (some gases are clear but coloured like chlorine gas).
The following is multiple choice question (with options) to answer.
Water vapor is an example of what? | [
"moistness",
"warmth",
"heat",
"coldness"
] | A | An example of moisture is water vapor in the atmosphere |
OpenBookQA | OpenBookQA-37 | thermodynamics, geophysics
With supercooled water, this effect is even more pronounced - a water at -30 °C has about the same density as water at 60 °C.
Oceans cool mostly by evaporation - the surface layers of water "spontaneously" changing state from liquid to gaseous. You get a balancing act between energy lost to evaporation, and incoming sunlight. However, there's a huge gap between the surface and the deeps, a lot of water mass - the incoming sunlight is nowhere near enough to warm ocean waters throughout. So you get warm surface waters, then a gradient of cooler and cooler water, and finally about 0-3 °C in the deep. To illustrate how big this gap is, about 90% of the worldwide ocean water is in the 0-3 °C range (hence the "nowhere near enough sunlight to heat the whole thing through").
Of course, a 4 °C body of water is great for cooling systems running at 40 °C and more. Air is actually a pretty good insulator, so air cooling gets tricky with large systems. Water, on the other hand, is pretty thermally conductive, and it easily convects, so cooling a huge data centre becomes almost trivial.
EDIT:
Let me address the Sun part, since there seems to be some confusion there as well.
Nuclear fusion is something that happens very infrequently. Two nuclei must come very close together to fuse, and they need enough kinetic energy to overcome the repulsion between each other (since both have the same electric charge).
The first problem is solved by increasing density. The more nuclei you have in the same volume, the higher the likelihood of close contact. This is where pressure comes in - that's how you get a higher density. Stars are made of plasma, and plasma is easily compressible, similar to a gas, so as pressure increases, so does density. How compressed is it? Well, the Sun's core, where the fusion reactions are actually happening, contains 34% of the Sun's mass, in only 0.8% of the Sun's volume. In the centre, the density is around 150 times the density of liquid water. The pressure is about 100 000 times the pressure in the Earth's core, and about 100 000 000 times the pressure of the water on the bottom of the Mariana trench.
The following is multiple choice question (with options) to answer.
Heat and moisture in the ocean is a good recipe for | [
"a violent storm",
"violent sea animals",
"condensation",
"inland storms"
] | A | an ocean is a source of heat and moisture for a hurricane |
OpenBookQA | OpenBookQA-38 | thermodynamics, temperature, water, states-of-matter, liquid-state
Title: Why is it possible to raise the temperature of water over the boiling point? For example, if we take water at a constant pressure and increase the temperature fast enough over the boiling point, the water will not boil. Why does it happens? It happens because the kinetics of boiling have a finite time scale. This is because to begin boiling, a nucleus must be furnished to trigger the phase change. That nucleus usually takes the form of an air bubble in a crack or crevice in the water container's walls. If the bubble exists when the boiling point is reached, boiling begins without delay. If no nucleus is available, the temperature rises above boiling and the heated water becomes metastable. Since the size of the nucleus required to trigger boiling decreases with increasing temperature, as the temperature rises above the boiling point, progressively smaller nuclei (if they exist) become active. In the case of no nuclei at all, random density fluctuations within the fluid serve as nuclei but even these require time to spontaneously appear.
This initiatory time lag gets smaller and smaller as the temperature climbs higher and higher above the boiling point. In the limit of extremely rapid heat deposition into the fluid, the time lag asymptotically approaches zero and the temperature at which this occurs is called the thermodynamic limit of superheat, which for water is about 340 C.
By heating up water at a rate of > 100 degrees C per microsecond, it is possible to achieve superheats of roughly 280 C, at which the enthalpy stored in the superheated water is sufficient to provide the heat of vaporization of that superheated water and the result is a violent, near-instantaneous vapor explosion.
The following is multiple choice question (with options) to answer.
if the boiling point of water is attained, what ensues beyond this point? | [
"the water turns evaporates rapidly",
"the water then solidifies",
"the water becomes black",
"all of these"
] | A | steam is a kind of water above 100 degrees celsius |
OpenBookQA | OpenBookQA-39 | inorganic-chemistry, acid-base, everyday-chemistry
$$\ce{H2O + CO2(aq) <=> H2CO3}$$
and the protolysis of true $\ce{H2CO3}$
$$\ce{H2CO3 <=> H+ + HCO3-}$$
For a weak acid
$$\begin{align}
\log[\ce{H+}]&\approx\frac12\left(\log K_\mathrm a+\log[\ce{H2CO3^*}]\right)\\
&=\frac12\left(-6.3-5.0\right)\\
&=-5.65\\
\mathrm{pH}&=5.65
\end{align}$$
Thus, pure rain in equilibrium with the atmosphere has about $\mathrm{pH}=5.65$. Any acid rain with lower $\mathrm{pH}$ would be caused by additional acids.
The following is multiple choice question (with options) to answer.
What is the most likely to be an effect of acid rain on an aquatic environment? | [
"decrease in plant life",
"increase in fish population",
"increase in plant growth",
"cleaner and clearer water"
] | A | acid rain has a negative impact on water quality |
OpenBookQA | OpenBookQA-40 | the-moon, moon-phases
Because the full Moon happens when the Moon and Sun are on opposite sides of the Earth, the Moon is most directly opposite the Sun near the Spring and fall equinox. That makes the Harvest Moon (full moon closest to the fall equinox) and the full Moon closest to the spring equinox, more directly opposite the sun, so they reflect slightly more light to the Earth. This effect basically just makes the Moon a bit rounder than other full moons. If you've ever noticed, mid summer or mid winter, the full moon can appear fatter than it is tall. That's not an illusion, it's due to the 5 degree inclination.
This effect on overall brightness is small, but your eyes might be noticing a rounder moon and seeing it as brighter. It's theoretically possible.
This year's largest moon was in March, so today's full moon is actually smaller than average. Astronomical measurements will always say that the closest full moon is the brightest one because it's larger in the sky and it reflects more total light towards the Earth, but apparent brightness to your eyes might have little to do with it's increasing or decreasing angular diameter and likely has more to do with how clear the night sky is. Our eyes can fool us. It's possible that the smaller moon appears brighter even though it reflects less light because it also scatters less light across the rest of the sky, similar to how a smaller flashlight might appear brighter if you stare into it, compared to a flashlight with a wider opening that gives off more total light.
A clear night is probably the best explanation. I'd pick that over smaller angular diameter or greater roundness. On a clear night, the Full Moon can appear brighter because less light gets scattered around it, making it look bright against a sky that's slightly darker, but you don't notice the sky's variation.
The full moon is also higher in the sky in winter, because it moves mostly opposite the sun. Being higher in the sky mans there's less atmosphere between the Moon and you. Directly overhead should be brighter than at an angle to a person viewing from Earth.
Edit
doing some looking I came across this website. It claims:
The following is multiple choice question (with options) to answer.
When the moon is full is has a different | [
"size",
"weight",
"distance",
"appearance"
] | D | the phases of the Moon change the appearance of the Moon |
OpenBookQA | OpenBookQA-41 | the-sun, coordinate
Title: Is the sun flipped on the other side of the world? As the orientation of the moon is different in the northern and the southern hemisphere, is the orientation of the sun different in both hemisphere?
Does a sunspot appearing in the Sun northern hemisphere from the Earth northern hemisphere will look as located in the Sun southern hemisphere from the Earth southern hemisphere ?
If I understand well, an equatorial mount can compensate for the Earth tilt, but how is possible to compensate from one hemisphere to the other one? Is the image flipped?
thank you! Yes, the orientation of the Sun will be different from the Earth's northern and southern hemisphere, just like your example of the Moon.
I would not say that a sunspot in the "northern" hemisphere would appear to be in the "southern" hemisphere just because of the change in orientation. North is fixed on the Sun and Moon, just like they are on the Earth. (If you turn a globe of the Earth "upside down", the northern and southern hemispheres do not switch, just the orientation."
The view through a telescope may change the orientation, but the directions North, South, East, and West on the Sun and Moon remain the same. The user of the telescope needs to determine which directions those are (up, down, left, right). It changes with the design of the telescope (reflector versus refractor) and the number of optical elements.
The following is multiple choice question (with options) to answer.
What happens when a hemisphere is tilted away from the sun? | [
"cools",
"nothing",
"heats",
"warms"
] | A | winter is when a hemisphere is tilted away from the sun |
OpenBookQA | OpenBookQA-42 | geology, fossil-fuel, petroleum
For some transport applications, the energy density is still a winning attribute of hydrocarbons: most notably, powered flight for freight and travel.
We already have two routes to non-fossil hydrocarbons: biological sources, and direct chemical synthesis. Each involves capturing atmospheric CO2, and combining with water, to generate a blend of hydrocarbons.
Now, we already have means of creating hydrocarbons suitable for flight (e.g. Jet-A and Jet-A1 fuels). And there are already demonstration plants that have closed-loop generation of synthetic hydrocarbons, for use in electricity-grid-balancing, by using surplus electricity to synthesise methane, which is then burnt in gas turbines when required. Similarly, Tony Marmont's team have been synthesising petrol (gasoline) from air, water, and electricity.
However, none of those things mean that hydrocarbons necessarily have much of a future, beyond plastics production. Because hydrocarbon-powered aviation has a lot of environmental problems beyond just CO2 emissions, in particular it makes other contributions to exacerbating global warming. And there are lots of options for energy storage within the electricity supply chain.
The following is multiple choice question (with options) to answer.
One renewable fuel source is | [
"vegetable oil",
"coal",
"fossil fuel",
"petroleum fuel"
] | A | alternative fuel is usually a renewable resource |
OpenBookQA | OpenBookQA-43 | thermodynamics, energy, electricity, efficient-energy-use
Title: Cutting down on power by bypassing mechanical to electrical conversions: Why not? The only answer to this I can think of is energy portability issues.
Another modern-world insanity is converting mechanical energy to electrical, only to turn it back into mechanical. The example I like to use is a refrigerator's reciprocating compressor.
If we directly attach a steam turbine's axle to the crankshaft of the compressor, we will not need to suffer losses in heat in our conversion of mechanical to electrical (at the power plant) then back to mechanical energy (in our appliance). Long ago, a primitive factory used one big engine or turbine or water wheel to rotate a set of overhead shafts, from which leather belts were suspended at intervals to power small pieces of machinery scattered throughout the factory. This arrangement was inflexible in that when the single big engine stopped, so did the entire factory, and when electricity came into common use, this overhead shafting arrangement fell quickly out of favor.
The power losses in long-distance electrical power transmission are more than made up for by the ease with which it is performed and the flexibility it affords. This makes "local power generation" as you describe it impractical because a hundred small steam turbines are much more wasteful of heat energy than one large turbine.
The only practical exception is integrated co-generation in which a small engine running on, for example, natural gas powers a generator while also spinning the shaft of a heat pump. The waste heat from the engine's cooling system makes residential hot water, the waste heat from its exhaust goes through a heat exchanger to provide hot air for space heating, the heat pump furnishes air conditioning (or pulls heat from outside the dwelling) and the electricity from the generator powers up your small appliances in the home while also charging a set of batteries.
Overall thermodynamic efficiency of such a device can exceed 95%, and examples of this technology are just now coming onto the market.
The following is multiple choice question (with options) to answer.
I can use electrical energy to | [
"Run a mile",
"Swim",
"bake a bagel",
"Rock climb"
] | C | a doorbell converts electrical energy into sound |
OpenBookQA | OpenBookQA-44 | • This answer is more intuitive than the @ross's answer, if you fleshed out why it's 8 ways, then 6, etc... this would be a great answer. – user138559 Apr 10 '16 at 22:16
• I think part of the elegance of this answer is that it doesn't require fleshing out. The answer self-fleshes. There is a hidden elegance even in the meaning of the "That's obvious" comment at the beginning. It sound's dismissive. But it's actually descriptive. – Mowzer Apr 11 '16 at 18:43
• Something rubs me the wrong way about "That's obvious". I don't think that language has a place on a Q&A site. If it was obvious, they wouldn't have asked. – JPhi1618 Apr 12 '16 at 14:19
• Telling the question asker "That's obvious" violates the Be nice principle that the Stack Exchange network and community tries to adhere to. You can write an answer without belittling the question asker. If it was obvious, then the question wouldn't be asked. Furthermore, you should flesh out what you mean by your various numbers and how you arrived at them. You just stated "8, then 6, then 4..." which is hard to read and understand. And Mowzer, you should not be encouraging this kind of language or vague answers. – The Anathema Apr 12 '16 at 17:58
• @TheAnathema I agree it took me a minute and to look back at the picture to see why $8,6\ldots$ make sense. I can imagine it'd take longer if you don't 'see it' and the answer doesn't help you arrive at it, except by giving the numbers. I do however agree it is intuitive once you see it. – snulty Apr 13 '16 at 12:15
Looking at the picture, there are 4 phases.
1. Draw the petals
2. Draw the upper stem
3. Draw the leaves
4. Draw the lower stem
Lets label these $A,B,C,D$. Clearly, the total number of ways to draw the flower is simply;
$$Total = A \times B \times C \times D$$
The following is multiple choice question (with options) to answer.
On the list of a flower's goals would be to | [
"produce carbon dioxide",
"deroot and die",
"produce offspring",
"remain sterile"
] | C | a flower 's purpose is to produce seeds |
OpenBookQA | OpenBookQA-45 | equipment, history-of-chemistry
Title: Help me identify this glassware! I'm a freshly graduated physics and math teacher moved into a small school from the late 1920s. The equipment here is old and confusing, at the very least. I have found many things which I have never seen before. I would like some help identifying what I have and what I can do with them, if anything.
(Click the images to view them at full size.)
1. A load of copper pots. For boiling something perhaps?
2. Some sort of wash bottle? Why is the cork on there?
3. I managed to make out "unitized wash bottle" on the back. This serves the same function as the last one, I presume.
4. It reminds me of a graduated cylinder until the frosted top and the "arms" that poke out the sides. What is this for?
5. This reminds me of halogen bulbs. Again, I have no idea what this is for.
6. I've taken to calling this "trumpet" glass pipe. What is it used for?
7. This large bulb has confused me since day one. I feel like it needs some sort of current passed through the ends. It reminds me of a cathode ray tube in a way. I'm completely lost on this one.
8. Here. Have a free safety poster! Not as good as old Carol, though. #4 is a collection vessel of some sort.
The ground glass fitting would have connected to some other ground glass fitting. A set of the ears would be on the connecting piece of glassware also. Then springs would hold the two pieces together.
The following is multiple choice question (with options) to answer.
A person wants to buy some reusable equipment for the kitchen, so they get | [
"paper plates",
"ceramic plates",
"solo cups",
"plastic forks"
] | B | something reusable can be used more than once |
OpenBookQA | OpenBookQA-46 | thermodynamics, temperature, phase-transition
If water and ice are both present finally, then T = 0
If only water is present finally, then $m_{if}=0$
If only ice is present finally, then $m_{wf}=0$
The following is multiple choice question (with options) to answer.
The only stage of the water cycle process that is nonexistent is | [
"evaporation",
"evaluation",
"precipitation",
"condensation"
] | B | evaporation is a stage in the water cycle process |
OpenBookQA | OpenBookQA-47 | Hey, thanks for your help guys. For a minute there, I thought that this theoretical person could not safely expect to live to be 82 years old.
9. Jun 16, 2012
### SW VandeCarr
In fact, on a purely probabilistic basis, for any finite time no matter how large, there is a non zero probability that a person would survive that long. So for a sufficiently large population, there would be a theoretic person that would live 100,000 years. This, of course, has no basis in biology.
In terms of the probability of being murdered, the model would not hold for the 100,000 year old person. In terms of the model, probably the best one can do is assume the proportion of causes of death would be constant. The calculation above needs to be corrected for overall survival in terms of death from any cause.
Last edited: Jun 16, 2012
10. Jun 16, 2012
### viraltux
Interesting... but 0.37% is not that small percentage, don't you think? That means, roughly speaking, that a community of around 300 persons can expect that one of them will be murdered.
If you consider that the number of people we know plus acquaintances can easily be around 300 persons that would mean that most 82 year old persons know of someone in their circles who has been murdered. Mmm... that might be an interesting survey.
11. Jun 16, 2012
### SW VandeCarr
As I said in my previous post, this is a misapplication of statistics. You have to consider survival in terms of all cause death. If you just consider the murder rate, then at some point nearly everyone gets murdered.
12. Jun 16, 2012
### moonman239
I know that.
This person will not die until he reaches age 82, if he is not murdered. As mentioned before, this person has a 68% chance of living to be 82.
13. Jun 16, 2012
### D H
Staff Emeritus
The probability of living to 82 per this problem is 99.63%, not 68%. You missed the decimal point on the 0.37%.
14. Jun 16, 2012
### SW VandeCarr
The following is multiple choice question (with options) to answer.
which of these would more likely survive? | [
"a lost dog by the river, with small rodents",
"a cat left in the desert",
"a man drifting a raft at sea without supplies",
"none of these"
] | A | the ability to access resources has a positive impact on an organism 's survival |
OpenBookQA | OpenBookQA-48 | 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 | [
"is smooth on the entire surface",
"contains large cavities cause by explosions",
"contains an internal core of cheese",
"is filled with lakes"
] | B | the moon 's surface contains many craters |
OpenBookQA | OpenBookQA-49 | mechanical-engineering, structural-engineering, control-engineering
For example, if I wanted to setup such a facility, who would I have to consult?
You either find a consulting engineering firm with a lot of experience in designing and planning (and building!) such a plant. Or you find anexperienced hydroponics expert (the first bullet point) and a consulting firm with experience in a relevant field like wastewater.
Alternativly, you find a company specialized in building and selling hydroponics farms. This will give you less choice over the final plant - the company will want to work with their preferred components and concepts, and crucially they will want to reuse as much egnineering work from previous projects as they can.
The following is multiple choice question (with options) to answer.
Greenhouses | [
"trap the dangerous gases released by plants",
"protect plants from snow and frost",
"keep plants from getting warm",
"protect plants from mild weather"
] | B | a greenhouse is used to protect plants from the cold |
OpenBookQA | OpenBookQA-50 | newtonian-mechanics, angular-momentum, conservation-laws, planets
Title: Why are the planets rotating on their own axis? Earth is revolving around sun because of gravity but what causes the earth to rotate itself?
This question has been already asked here, but the answers are like, earth had a collision and it formed moon so it started rotating. But what is it with the case of all other planets?
Every planet is rotating on its own axis that too venus and mercury has no moons, so what caused them rotating? First of all, you must know how the Earth formed. When the Sun first formed by the compression of nebulae matter, the rest of the nebula consisted of quite a few debris, that began to orbit around the sun. These debris eventually clumped together and formed planets. So basically, the particles that make up the Earth were already in motion. As they clumped together, they still retained their velocity, and of course, their angular momentum about the Earth's to be axis. The Earth has been spinning from the day (can I use the word day?) it was created.
Further reading (for the fun of it):
Why does the Earth rotate?
How was the Sun formed?
Angular momentum
The following is multiple choice question (with options) to answer.
Earth rotating causes | [
"the cycling of AM and PM",
"the creation of volcanic eruptions",
"the cycling of the tides",
"the creation of gravity"
] | A | a planet rotating causes cycles of day and night on that planet |
OpenBookQA | OpenBookQA-51 | education
Title: Conduction, Convection, or Radiation Am I using Conduction, Convection, or Radiation when cooking in the oven using a metal tray vs. a glass tray? As mentioned in the comments , all heat transfer methods are present in the oven, particularly one with a fan.
In glass versus metal tray, the metal tray will heat faster than the glass one because it is more conducting and will reach the equillibrium temperature of the oven faster, by absorbing radiation and heat from convection, and spreading faster to the bottom of the food, but once there, there is no difference in the way the food is cooked, to first order. It might be that for high settings of temperature the metal tray heats faster in the thermostatic on/off, and because of conduction the bottom of the food bulk might brown and "catch" versus a glass tray that heats slower and transfers heat slower.
The following is multiple choice question (with options) to answer.
which one of these can help a person cook their food? | [
"a stack of clothes",
"a stack of cans",
"a pack of cigarettes",
"a counter cooker appliance"
] | D | a stove generates heat for cooking usually |
OpenBookQA | OpenBookQA-52 | temperature, light, heat
Title: Why does sunburn cause fever? Today I found out that sunburns can cause fever.
What I don't understand is how/why? In my understanding fever is the side effect of an immune reaction against an intruder, mainly bacteria (though I admit I can be wrong).
Google searches like "can sunburn cause fever" only bring up that it is possible, but not why. Here is a good article on the topic.
https://www.nlm.nih.gov/medlineplus/ency/article/003227.htm
But it's most likely due to the fact that a sun burn is an actual burn on the skin that can cause inflammation, inflammation can in turn cause fever. Also having a really bad sunburn can open you up more to the possibilities of skin infections. If this happens then once again you might get a fever due to infection. If you really want to find out more on the cause of fever after sunburn you need to examine the pathophysiology of fever and why fever happens. I bet my money on fever due to skin inflammation after a sunburn, I guess the real question would be why does inflammation cause fever since sunburn = skin inflammation
Here is a good article
http://antranik.org/inflammation-and-the-pathophysiology-of-fever/
The following is multiple choice question (with options) to answer.
Sunlight produces heat that causes | [
"dogs to bark",
"stones to form",
"warmth on bodies",
"plastic to form"
] | C | sunlight produces heat |
OpenBookQA | OpenBookQA-53 | homework-and-exercises, optics, lenses, camera
Title: Size of object from its image If the quality of the camera (i.e. the megapixels) (assume to be $x$) of the camera is known and an object is kept a known distance from the camera (assume to be $d$), can the actual width and length of the object be determined? Yes it can, if you know the focal length as well.
Assume that the focal length is $f$ and the distance from lens to object is $d$.
To get the object in focus, you need the distance from the lens to the sensor to be
$$f' = \frac{f * d}{f + d}$$
Once you have the distance from the optical center to the sensor, you know the magnification:
$$M = \frac{d}{f'}$$
which in most practical situations will be a "minification" (i.e. $d \gt f'$).
Finally you divide the size of the image on the sensor by the magnification to get the object size. If the image is $m\times n$ pixels of size $p$ each, then the object size is
$$width = \frac{m \cdot p\cdot d }{f'} = \frac{m \cdot p \;(f+d)}{f}$$
and similarly for the height.
Now the size of the pixels can usually be derived from the sensor type. It is not quite enough to know you have a "12 Mpix" camera, as sensors come in (many) different sizes. Typically the best cameras have the largest sensors (and large lenses). To complicate matters further, some camera manufacturers will quote the focal length of the lens in "equivalent for 35 mm" (especially for super zoom cameras with "1200 mm" telephoto capability). But that is going a bit off topic perhaps. See https://mattsassamatt.files.wordpress.com/2011/09/sensor-size7.png for a chart (somewhat out of date) of different sensor sizes, from which you can calculate the parameter $p$ I used above.
Let me know if you have enough information here.
The following is multiple choice question (with options) to answer.
with which could you tell the exact size of an object? | [
"a plain stick with irregular shape",
"a plastic tape with graduated markings",
"a thermometer with mercury in it",
"a metal cooking spoon"
] | B | a tape measure is used to measure length |
OpenBookQA | OpenBookQA-54 | speciation, artificial-selection
Title: Is there any artificial species (in particular, an artificial species of animal)? Dogs were artificially selected from wolves, but a dog and a wolf can produce fertile offspring, and thus are of the same species. I had heard that the aurochs and cattle were different species, but I could not find this information anywhere. I had heard also that some artificially selected flies are considered to be a new species.
Is there any human-made species (especially a species of animal) which is not able to produce fertile offspring witch any other species, in particular with the one from which it evolved?
EDIT: (A similar question in different words.) Is there any human-made animal lineage which was conceived by artificial selection and which is broadly accepted as not being a race or subspecies, but a species on its own. Artificial selection leading to new species - Domestication
As you talk about dogs in your intro, let's consider them.
You will fail to breed a great dane and chihuahua for obvious mechanical reasons. You will also fail to breed a chihuahua with a wolf. So, yes artificial selection have lead to reproductive isolation.
Artificial selection leading to new species - lab experiment
Artificial selection have also lead to reproductive isolation in non-domesticated species. See for example the post Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?
Concept of species
As a side note... Above, I consider the so-called 'biological species concept'. For a discussion on the definition of species, please have a look at this post.
The following is multiple choice question (with options) to answer.
Which would be the result of the breeding of two wolves? | [
"kittens",
"wolf pups",
"fox pups",
"dog pups"
] | B | reproduction produces offspring |
OpenBookQA | OpenBookQA-55 | Z_C:=\frac{CX}{\|CX\|}=\frac{CX}{\|X_C\|}\tag{5}
Removing size or scale means scaling to the unit size. Thereby, two configurations with different sizes lose their size information and also their scale. The scale is a quantity that expresses the ratio between sizes of two configurations, either two with different shapes or two with the same shape (one is the scaled version of the other one). In another scenario (like the full Procrustes analyses), if two or more configuration are scaled with different scale (factors), they also lose their scale/size information (relative to each other) although their sizes may not be unit.
12) Reworded definition of a shape: A shape is an equivalence class of geometrical figures/objects/configurations modulo (what remains after) the similarity transformation. The shape of X is denoted by [X]. In order to visualise the shape of an configuration, a representative of the equivalence class is considered and called icon, denoted by [X].
Two configurations and have the same shape, i.e. iff there exist such that:
X’=\beta X \Gamma + 1_k\gamma^{\text T}
In other words, two configurations have the same shape if they perfectly match after the removal of their location, rotation, and size/scale.
13) Shape space is the space/set of all shapes, i.e. equivalence classes. For example . All have their locations, rotations, and size removed.
14) Reworded definition of form (size-and-shape): form is an equivalence class of geometrical configurations modulo translation and rotation. The form/size-and-shape of a configuration/object X is denoted by , i.e an icon for the class. Two configuration and have the same form, i.e. iff there exist such that:
X’=\Gamma X + 1_k\gamma^{\text T}
15) Size-and-Shape/Form space is the space/set of all forms, i.e. equivalence classes. For example .
16) By removing the size of a form (scaling to unit centroid size) of a configuration, the shape of the configuration is obtained.
The following is multiple choice question (with options) to answer.
Scales | [
"measure how much belly fat the user has",
"measure height of the user",
"help users know if they need to drop some lbs.",
"help users determine their blood sugar levels"
] | C | a scale is used for measuring weight |
OpenBookQA | OpenBookQA-56 | biochemistry, food
Title: Who creates first nitrogen compounds in the food supply chain As I understand the food supply chain, organic compounds have to be created from a unlimited source (air, water...).
For instance, I figure that plants transform CO2 from air to organic carbon compounds, mainly carbohydrates, which are then the main source for most other life forms.
But I never heard about a plant turning atmospheric N2 to nitrogen compounds.
Where nitrogen compounds come from, and from which source ? There are nitrogen fixing bacteria who turn N2 into NH3. Some are free-living in soil, others live symbiotically with plants.
https://en.wikipedia.org/wiki/Nitrogen_fixation
The following is multiple choice question (with options) to answer.
When producers create food in an ecosystem, a portion of the nutrients are | [
"carbs",
"energy",
"grass",
"flowers"
] | A | a producer is a source of sugar in an ecosystem |
OpenBookQA | OpenBookQA-57 | # related rates help!!!
• November 15th 2007, 04:53 PM
singh1030
related rates help!!!
At noon, ship A is 125 km east of ship B. Ship A is sailing west at 35 http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif, and ship B is sailing north at 35 http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif. How fast is the distance between the ships changing at 2:00 P.M. in http://maple-ta.nss.udel.edu:8080/tm...pogppajdcb.gif?
• November 15th 2007, 05:35 PM
Soroban
Hello, singh!
Quote:
At noon, ship A is 125 km east of ship B.
Ship A is sailing west at 35 km/hr, and ship B is sailing north at 35 km/hr.
How fast is the distance between the ships changing at 2:00 P.M.?
I hope you made a sketch . . .
Code:
B * | \ | \ | \ 35t | \ x | \ | \ | \ * - - - - - - - * - - - - - - * Q 125-35t A 35t P : - - - - - - 125 - - - - - - :
At noon, ship A is at point P.
In $t$ hours, it has moved 35t km to point A.
Then: $AP \:=\:x$, and $QA \:=\:125-35t$
At noon, ship B is at point Q.
In $t$ hours, it has moved 35t km to point B.
Their distance is: . $x \;=\;\sqrt{(125-35t)^2 + (35t)^2}$
So we have: . $x \;=\;\left(2450t^2 - 8750t + 15,625)^{\frac{1}{2}}$
Can you finish the problem?
• November 15th 2007, 05:39 PM
poofighter
The following is multiple choice question (with options) to answer.
Two ships grazing each other as they pass will | [
"cause mayhem",
"sink them",
"speed them up",
"slow them down"
] | D | friction acts to counter the motion of two objects when their surfaces are touching |
OpenBookQA | OpenBookQA-58 | biochemistry, botany, plant-physiology, photosynthesis, agriculture
The above image is an example of a "potato battery" made without the potato. Identical setup and the energy obtained is identical given everything else the same.
Potato power- er, metal power?
This experiment is supposed to demonstrate the concept of an electrochemical cell. Electrochemical cells obtain their energy from the reduction-oxidation reactions that happen between two metals with different reduction potentials. When two metals - such as copper and zinc - are placed in a medium that permits the exchange of electrons and ions, an electrical gradient is produced as electrons move from one metal to the other and ions move the other direction. This gradient can then be captured and used to do work such as powering a lightbulb or an AI.
In the potato powered example, the power comes from zinc and copper. If you want a more powerful battery, use more zinc and more copper- not a bigger potato. If that is not good enough, try replacing the zinc with something like lithium- this is what we've done with modern, rechargeable batteries.
In truth, the potato battery would be better described as a normal battery that just happens to be inserted into a potato. You'll make a better battery if you use copper pennies and aluminum foil in vinegar.
I do not mean to shoot down your idea, and I am glad you are looking into renewable energy sources- but you may be better served by a class on electricity and batteries than by asking questions on biology.SE!
EDIT: I would assume that the electrical potential of this kind would also kill the plant, given that you're essentially electrocuting it. However, I was unable to find any information on the resistance of potato plants to electrocution.
The following is multiple choice question (with options) to answer.
A battery converts chemical energy into | [
"energy stored due to the relative positions of charged particles or electric fields",
"energy stored due to the bombardment of particles",
"energy stored between the cells of nonadjacent particles",
"energy that is broken down in particles"
] | A | a battery converts chemical energy into electrical energy |
OpenBookQA | OpenBookQA-59 | botany, color
Hypothesis 1
It should be remembered that chlorophyll is far from being the only pigment found in leaves. For example, carotenoids - which give yellow and reddish colors - are present in plant leaves. There are many carotenoids (according to Wikipedia there are over 1100 known, but that number will continue to grow). The biological roles of these carotenoids are also varied. In the course of the question, we may be interested, for example, in the photoprotective role of carotenoids. They are involved in the deactivation of reactive oxygen species (ROS). ROS can be formed during photosynthesis and can potentially be harmful to cells. Therefore, in conditions of excess solar radiation, plants can increase concentrations of carotenoids to prevent oxidative stress. It has already been pointed out to you in the comments that younger leaves look yellow - this is a common occurrence. The leaf is a very expensive organ, in the sense that the plant invests a lot of plastic substances in its development. So it makes sense that young, growing leaves get extra protection. That is, a young leaf that has not yet formed all the necessary structures (thick enough cuticle, efficient conductive system, etc.) is less efficient in terms of photosynthesis and therefore more susceptible to negative processes of photodamage. Increased concentrations of carotenoids, among other things, can reduce such risks. If you add to this the small thickness, it is understandable why young leaves often look more yellow.
Hypothesis 2
I have already said that leaves are expensive organs. They have a high protein content, which is very valuable to the plant. If a leaf is damaged or aged, there is a threat of irreversible loss of protein, which would be a great waste. Therefore, in such cases, plants trigger complex processes of removing valuable substances from the leaves. In particular, chlorophyll begins to break down, and the decomposition products are transported to the more durable parts of the plant. This is the reason why leaves change color in the fall, before defoliation. When the concentration of chlorophyll decreases, other pigments, such as carotenoids, increasingly affect leaf color. That's why damaged and old leaves often turn yellowish.
Although, I doubt that in the case of your plant, this process is often the cause for yellow leaves.
Hypothesis 3
The following is multiple choice question (with options) to answer.
The leaves of a plant benefit from? | [
"dog",
"sun",
"human",
"dust"
] | B | chlorophyll is used for absorbing light energy by plants |
OpenBookQA | OpenBookQA-60 | optics, atmospheric-science, weather
Title: Explanation for an unexpected rainbow Yesterday, I observed an unexpected rainbow in the sky. There was no forecast for rain, neither was it raining anywhere nearby. I have been trying to find an explanation but don't seem to find any. Can someone please explain what this rainbow is?
Note:the colours were way more vivid as compare to the picture I have taken These are tropospheric Iridescent Clouds
According to AtmosphericOptics:
When parts of clouds are thin and have similar size droplets, diffraction can make them shine with colours like a corona. In fact, the colours are essentially corona fragments. The effect is called cloud iridescence or irisation...
The usually delicate colours can be in almost random patches or bands at cloud edges. They are only organised into coronal rings when the droplet size is uniform right across the cloud. The bands and colours change or come and go as the cloud evolves...Iridescence is seen mostly when part of a cloud is forming because then all the droplets have a similar history and consequently have a similar size.
I've saturated the image so the interesting part can be appreciated
And here you have a very similar observation I quickly found by google image search:
The following is multiple choice question (with options) to answer.
Quartz may produce rainbows when light is shined | [
"around the crystal's area",
"through any of its sides",
"in the room its in",
"in to a mirror at it"
] | B | a quartz is made of six-sided transparent crystals |
OpenBookQA | OpenBookQA-61 | fossils, drilling
Title: What would people drilling through Mount Everest find? I am interested in knowing what kind of fossils we would find if we were to drill horizontally through the mountain and what we would find if we were to drill vertically. Would we find anything interesting other than the fossils? Looks like some basic hints are necessary (as a complement to @AndyM's answer):
stratigraphy usually goes from younger to older when going down.
there'll be little chance to find any macrofossils in rocks that formed before sufficiently complex life was around.
there'll be little chance to find fossils in rocks that underwent metamorphism, that is have been in pressure/temperature regimes that aren't conducive for their preservation, even if they initially were present in the pre existing rocks.
'trace fossils' are not small remains of fossils but fossilized traces ('footprints'). Very rare thing.
it may be possible to find fossils in overlaying, younger sediments that formed during or after the uplift or were trapped or transported in depressions, but that's not the point of the question I think.
So, below the uppermost formations around the summit you'll likely find nothing of interest in the sense of the question when drilling down.
Will provide sources on specificically focussed request, but this isn't top notch geoscience.
The following is multiple choice question (with options) to answer.
A woman is digging under a tree on a tall mountain. She is looking for interesting rocks, and a foot down into the soil, discovers a fossilized fish skeleton. From this discovery, the woman is able to determine that | [
"the mountain used to be underwater",
"some bears in mountains eat fish",
"some fish can climb mountains",
"sometimes rain can move fish to high spaces"
] | A | if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past |
OpenBookQA | OpenBookQA-62 | zoology, sensation
Title: Can animals that rely heavily on sonar sense colour? Apparently there're species around as rely heavily on sonar to sense the world around them.
E.g. Bat, Dolphin, Whale ...
The humans, and other terrestrial beings in a lighted world are capable of distinguishing colour in varying degrees of acuity. Is this ability to sense colour in our environment applicable to species (terrestrial, avian, and marine) that rely heavily on sonar? Any animal using sound cannot sense color though sonar directly, though these animals are not entirely blind and can probably see colors in the infrared we can't.
Even on the darkest night there is some light around and all bats use this. Old World fruit bats have colour vision, which is useful to them as they are often quite active in daytime, roosting on trees in exposed positions, rather than tucked away in dark crevices like most microbats, which can see only in black-and-white.
Dolphins have additional senses in addition to seeing they can sense electrical fields. So if an animal has its eyes covered, they will seem to be able to do things you would not expect. Its not the same as seeing the color though.
Such animals using sonar can additionally sense density and hardness as well as other material attributes which would cause the acoustic properties of the material as well as movement.
A hard-bodied insect produces a different quality of echo from one with a soft body, so bats can distinguish between some different groups of insects in this way. They can also determine the size of the object.
What's really interesting is that even human beings can experience this unusual sense. Blind people have learned to echolocate by making clicks with their mouth, and there is a movement to teach this skill.
Anyone can try it. In just an hour or two I was able to tell how close I was to a wall, whether the wall was concrete. I couldn't play video games (2:20 on the link) or see colors though.
The following is multiple choice question (with options) to answer.
Which animal lacks the ability to see by sensing light? | [
"Southern cave crayfish",
"lobster",
"cod",
"salmon"
] | A | eyes are used for seeing by animals by sensing light |
OpenBookQA | OpenBookQA-63 | zoology, sensation
Title: Can animals that rely heavily on sonar sense colour? Apparently there're species around as rely heavily on sonar to sense the world around them.
E.g. Bat, Dolphin, Whale ...
The humans, and other terrestrial beings in a lighted world are capable of distinguishing colour in varying degrees of acuity. Is this ability to sense colour in our environment applicable to species (terrestrial, avian, and marine) that rely heavily on sonar? Any animal using sound cannot sense color though sonar directly, though these animals are not entirely blind and can probably see colors in the infrared we can't.
Even on the darkest night there is some light around and all bats use this. Old World fruit bats have colour vision, which is useful to them as they are often quite active in daytime, roosting on trees in exposed positions, rather than tucked away in dark crevices like most microbats, which can see only in black-and-white.
Dolphins have additional senses in addition to seeing they can sense electrical fields. So if an animal has its eyes covered, they will seem to be able to do things you would not expect. Its not the same as seeing the color though.
Such animals using sonar can additionally sense density and hardness as well as other material attributes which would cause the acoustic properties of the material as well as movement.
A hard-bodied insect produces a different quality of echo from one with a soft body, so bats can distinguish between some different groups of insects in this way. They can also determine the size of the object.
What's really interesting is that even human beings can experience this unusual sense. Blind people have learned to echolocate by making clicks with their mouth, and there is a movement to teach this skill.
Anyone can try it. In just an hour or two I was able to tell how close I was to a wall, whether the wall was concrete. I couldn't play video games (2:20 on the link) or see colors though.
The following is multiple choice question (with options) to answer.
Which animal emits something that many autistic people would be extra sensitive to? | [
"cow",
"dog",
"cat",
"skunk"
] | D | a skunk produces a bad odor |
OpenBookQA | OpenBookQA-64 | sun
Title: Is there an instance where the sun sets or rises partly, then return back? I am reading Longest Sunset from XKCD. At first, I've thought that he mentions these phenomena just for fun, but it turns out to me that it might happens, based on the level of somewhat seriousness that I perceive from his writing. He doesn't talk about that in detail.
For the sunset:
Sunset starts the instant the Sun touches the horizon, and ends when it disappears completely. If the Sun touches the horizon and then lifts back up, the sunset is disqualified.
I'm not sure if the sunset is disqualified is because it happens, but we don't count it, or because he's just making fun. But I can't prove that this cannot happen. The more we head to the poles, the shorter the night is. Ultimately there will be a point that the sun still sets, but not completely, right?
For the sunrise:
For the purposes of our question, this is not a sunset:
The phrase for our purposes strengthen my doubt that he is being serious. The logic is the same above.
But these two illustrations are in the series of other apparently amusing ones, which are the sun as the cell in division, or as the egg in hatching (if you read the book, you will see this effect stronger).
So, is there an instance where the sun sets or rises partly, then return back? Yes, such sunrises happens every year at the beginning and end of the polar nights at high latitudes. One can have a few days with a glimpse of the sun but disqualified sunsets and sunrises.
Sunsets occur at the end of the midnight sun period by the end of the summer, the first sunset is not complete.
Sun at it's highest elevation at midday. (To be honest, the picture might be taken the day after the first sunrise, as some mountains are hiding the horizon.)
Here is e.g. an article from Svalbardsposten, the northernmost newspaper in the world, reporting of the first rays of sunlight after the polar night and some pictures from the last sunrise/sunset before the polar night in northern Sweden.
The same occurs at the southern polar circle and south thereof, unless it's cloudy...
Update: here is a great time laps from Davis Station in the Vestfold Hills showing exactly what you asked about: Mid winter
The following is multiple choice question (with options) to answer.
which of these usually occur over the shortest period? | [
"a super size earthquake",
"a torrential rain fall",
"all of these",
"the eruption of a volcano"
] | A | an earthquake usually occurs over a period of 10 to 30 seconds |
OpenBookQA | OpenBookQA-65 | sun
Title: Is there an instance where the sun sets or rises partly, then return back? I am reading Longest Sunset from XKCD. At first, I've thought that he mentions these phenomena just for fun, but it turns out to me that it might happens, based on the level of somewhat seriousness that I perceive from his writing. He doesn't talk about that in detail.
For the sunset:
Sunset starts the instant the Sun touches the horizon, and ends when it disappears completely. If the Sun touches the horizon and then lifts back up, the sunset is disqualified.
I'm not sure if the sunset is disqualified is because it happens, but we don't count it, or because he's just making fun. But I can't prove that this cannot happen. The more we head to the poles, the shorter the night is. Ultimately there will be a point that the sun still sets, but not completely, right?
For the sunrise:
For the purposes of our question, this is not a sunset:
The phrase for our purposes strengthen my doubt that he is being serious. The logic is the same above.
But these two illustrations are in the series of other apparently amusing ones, which are the sun as the cell in division, or as the egg in hatching (if you read the book, you will see this effect stronger).
So, is there an instance where the sun sets or rises partly, then return back? Yes, such sunrises happens every year at the beginning and end of the polar nights at high latitudes. One can have a few days with a glimpse of the sun but disqualified sunsets and sunrises.
Sunsets occur at the end of the midnight sun period by the end of the summer, the first sunset is not complete.
Sun at it's highest elevation at midday. (To be honest, the picture might be taken the day after the first sunrise, as some mountains are hiding the horizon.)
Here is e.g. an article from Svalbardsposten, the northernmost newspaper in the world, reporting of the first rays of sunlight after the polar night and some pictures from the last sunrise/sunset before the polar night in northern Sweden.
The same occurs at the southern polar circle and south thereof, unless it's cloudy...
Update: here is a great time laps from Davis Station in the Vestfold Hills showing exactly what you asked about: Mid winter
The following is multiple choice question (with options) to answer.
If the sun has set it is | [
"easy to cook a meal",
"time to eat breakfast",
"necessary to wear a coat",
"harder to see outside"
] | D | if it is night then the sun has set |
OpenBookQA | OpenBookQA-66 | optics, geometric-optics, lenses
I found a hand magnifier whose focal length was approximately $5$ cm and set it up to be about $4$ cm from the lens so that the virtual image would be about 25 cm from the lens.
I then put another grid 25 cm from the lens as shown in the photograph.
What was pleasing was that the iPhone simultaneously brought into focus the grid viewed through the lens and the grid 25 cm below the lens.
Note that the grid 4 cm from the lens was out of focus and "bigger" than the grid 25 cm from the lens.
If I had used that as my direct view grid as the reference the magnification found would have been in error.
10 magnified small squares were equal to 63 unmagnified small squares which gave a magnification of approximately $6$ which is not bad when compared with the theoretical value of $\frac {25}{4} \approx 6$.
So perhaps it is worth having another go at measuring the magnification of your $12$ cm lens noting that it is not only the focal length but the optical configuration which determines the magnification?
Later
The magnification $M$ of a magnifying glass is defined as
$$M = \dfrac{\text{angle subtended by image of object when 25 cm from the lens}}{\text{angle subtended by object when 25 cm from the naked eye}} = \dfrac {\alpha '}{\alpha}$$
The HyperPhysics article Simple Magnifier gives some more theory.
The following is multiple choice question (with options) to answer.
A magnifying glass | [
"would allow the user to better view the legs on an ant",
"would enhance the smell of a viewed specimen",
"would blur the legs of an ant",
"would enhance the feel of the user"
] | A | magnifying glass is used to see small things by making objects appear bigger |
OpenBookQA | OpenBookQA-67 | newtonian-mechanics, rotational-dynamics, air
Title: Direction of rotation of a celing fan From Constellation Energy
Quick energy efficiency tip: To stay cool and manage your energy at
the same time, use ceiling fans to create a “wind chill” in rooms you
are using. The wind chill will help you feel cooler than the actual
temperature. Make sure the ceiling fan is set to turn in a
counter-clockwise rotation.
I was wondering why the ceiling fan is set to turn in a counter-clockwise rotation, instead of the other way around?
Thanks! The blades of a ceiling fan are pitched out of plane slightly. As a result, when the fan spins, the blades push air either up towards the ceiling or down towards the floor. Which direction it pushes air is determined by the direction the fan is spinning, and the direction the blades are pitched. The usual convention is given by the right hand rule: if you hold your right hand so that you can curl your fingers in the direction the fan is spinning, then it will push air in the direction that your thumb is pointing.1 When it's pushing air down on you, it will then be spinning in a counter clockwise direction as you look up at it. You can make it follow a left hand rule by reversing the pitch of the blades.
Once you have set the direction of the pitch of the blades, you can reverse the airflow by reversing the direction the fan spins. Many (most?) modern ceiling fans provide some mechanism to do this. The fans in my house have a small black switch that slides up and down. @Ignacio Vazquez-Abreams mentions using a pull chain in a comment to another answer.
In warm weather, you set the fan so that it pushes air down towards the floor. This causes you to feel a breeze, which cools you. In cold weather, you set the fan so that it pushes air up into the ceiling. You don't feel a breeze,2 but it circulates warm air from the ceiling towards the walls and down towards the floor.
The following is multiple choice question (with options) to answer.
What do rotating vanes on an electric fan do to air? | [
"dampen",
"circulate",
"cool",
"warm"
] | B | the vanes rotating in an electric fan causes air to move |
OpenBookQA | OpenBookQA-68 | evolution, anatomy, organs
Title: Why Is Most Life Symmetrical Externally But Not Internally? Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance.
Take a human for instance, make a line from the top of our head right down the middle. However, internally it is not the same. Our organs excluding the kidneys, lungs, reproductive organs, etc are not symmetrically placed in our body.
The following is multiple choice question (with options) to answer.
An animal would have its inner parts better protected if it had which of these? | [
"a backpack on its back",
"a calcium fortified internal structure",
"none of these",
"a shell of cotton"
] | B | the skeletal system protects internal organs |
OpenBookQA | OpenBookQA-69 | evolution, biochemistry, plant-physiology, plant-anatomy, life
Title: Plants without bacteria? is it theoretically possible? I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But it is a natural way.
But is it possible to have a world with plants (without mammals or microorganisms and without bacteria) that could exist in the long term. Saying the atmosphere of these world has already enough nitrogen, oxygen and CO2, and of course there is water.
What could break this artificially created world with such conditions (say the world created not from low-level living structures)?
Could bacteria emerge in the world? This is the sort of question that should be considered from more than one perspective. Since this is speculation, take it as a given that there is a lot of 'what if' here.
I doubt most animals and plants can do entirely without bacteria - as you say most of the essential nutrients come from bacteria, who fix nitrogen. If only plants were left on earth, eventually the plants would use up all the nitrogen and they would have to find a way to fix more.
Can bacteria emerge from just a world of plants? I don't think viruses arise spontaneously, but since genomes often have viruses embedded in them, over the course of a billion years or so, its possible since bacteria and viruses continue to be impressed upon our genomes. Would it happen in time? Most would be skeptical whether that timing could work out.
In practice it would be hard to create a world like this. I would be interested to see whether you could sterilize the microorganisms off of seeds without killing the plant for instance. If you're asking about a small sterile environment with only plants, you could do it by adding the nutrients the plants need and giving them sunlight. Such self sustaining systems have been made with cyanobacteria and i'd be surprised if plants could not be included. But these are closed systems and judged by limited amounts of time, so whether this is an answer to your question is not clear. Here it looks like some water plants and fish have been done. If there was a plant that created CO₂ at an adequate rate its possible.
The following is multiple choice question (with options) to answer.
Plants require this to grow | [
"fertilizer",
"cool temperatures",
"non-organic matter",
"H2O"
] | D | a plants require water for to grow |
OpenBookQA | OpenBookQA-70 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
Renewable resources | [
"often come from fossil fuels",
"take centuries to biodegrade",
"can be used ad infinitum",
"should be used conservatively"
] | C | renewable resources can be used over again |
OpenBookQA | OpenBookQA-71 | So our resultant is 30.8 meters, 35.8 degrees north of west. What we can see is that if there is an obstacle in the path here, some big rock that you want to avoid, you can get to the same place by taking a different route which is kind of obvious, but now we just sort of demonstrated that that's true using analytical techniques.
The following is multiple choice question (with options) to answer.
a day hiking will most likely result in which of these? | [
"a paling of the skin",
"a greening of the skin",
"an even darker tone",
"none of these"
] | C | if something is outside during the day then that something will receive sunlight |
OpenBookQA | OpenBookQA-72 | refraction, geometric-optics
=v_x\hat{i}+v_y\hat{j}+v_z\hat{k} \\
=v_x\hat{e}_1+v_y\hat{e}_2+v_z\hat{e}_3
$$
The following is multiple choice question (with options) to answer.
Refraction | [
"makes objects appear to be twice their size",
"moves heat energy thru sound waves",
"is the phenomenon involved in mirrors",
"makes a straw appear broken when in a cup of water"
] | D | refraction causes something to look different |
OpenBookQA | OpenBookQA-73 | 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.
which of these can be considered a stage in the water cycle? | [
"all of these",
"the combination of nails and hammers",
"the presence of H20",
"the combination of chlorine and gas"
] | C | condensation is a stage in the water cycle process |
OpenBookQA | OpenBookQA-74 | zoology, mathematical-models, software, imaging
Title: What would it take to recognize a deer by its photo? I am trying to recognize a deer by its antlers or any other means.
Elaborating:
I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so it would be difficult to recognize it from the last year's photo unless these antlers retain the same pattern every year.
If not the antlers, what other characteristics should I be looking for?
Is there any software that can help me in recognizing a deer? There is a lot of variation in how and when deer shed their antlers. In most arctic and temperate-zone species, antler growth and shedding is annual, and is controlled by the length of daylight. In tropical species, antlers may be shed at any time of year, and in some species such as the sambar, antlers last several years. Some equatorial deer never shed their antlers.
The horns change every year and, especially, increase the number of branches (and consequently, change their shape). You can't recognize them by antlers, but by other features, such as color of the hair or the lineaments. Like us, animals have individual morphological differences that are recognizable and listable.
Biologists specializing in studies of particular animal species not only take photos, but also make drawings and write descriptions of behavior, to identify individuals within herds.
An optical examination, however, of the subject through drawings and photos (and if possible, direct observation), is more useful than a PC program. This involves identifying particular similarities and equalities that are not "identical". This is possible to do visually on a large (but limited) number of specimens. The human eye is the best computer.
The following is multiple choice question (with options) to answer.
Which of these items is required for a deer to live | [
"sun",
"iron",
"sand",
"cafeteria"
] | A | the sun is the source of energy for life on Earth |
OpenBookQA | OpenBookQA-75 | Tourist Places In Coimbatore Near Gandhipuram, Sunrunner Pembroke Welsh Corgis, Where Is Serana In Fort Dawnguard, Hello Etch A Sketch Font, Monkey King Characters, Adam Bradley Amazon,
The following is multiple choice question (with options) to answer.
Where is the best place to shoot animals? | [
"national park",
"sky",
"forest",
"sea"
] | C | national parks limit hunting |
OpenBookQA | OpenBookQA-76 | Case I: The spider at $A$ moves to $B$.
The spider at $C$ can only move to $D$ or $G$ (since $CE$ isn't an edge). If the spider at $C$ moves to $D$, then there are two ways for the spiders at $F,H$ to move: $(A,C,F,H) \to (B,D,E,G)$ or $(A,C,F,H) \to (B,D,G,E)$. If the spider at $C$ moves to $G$, then there is only one way for the spiders at $F,H$ to move: $(A,C,F,H) \to (B,G,E,D)$ (because $BH$ and $DF$ aren't edges). This gives $3$ ways for the spiders at $A,C,F,H$ to move to distinct vertices if the spider at $A$ moves to $B$.
Case II: The spider at $A$ moves to $D$.
Similarly to Case I, there are $3$ total ways for the spiders at $A,C,F,H$ to move to distinct vertices if the spider at $A$ moves to $D$.
Case III: The spider at $A$ moves to $E$.
Similarly to Case I, there are $3$ total ways for the spiders at $A,C,F,H$ to move to distinct vertices if the spider at $A$ moves to $E$.
This gives us $9$ ways for the spiders at $A,C,F,H$ to end up at distinct locations. Hence, the probability of no two of these spiders ending up at the same vertex is $\dfrac{9}{81} = \dfrac{1}{9}$.
The following is multiple choice question (with options) to answer.
Spiders can catch prey by doing all aside from | [
"building webs",
"building traps",
"hunting",
"howling"
] | D | a spider web is used to capture food by spiders |
OpenBookQA | OpenBookQA-77 | thermodynamics, solid-state-physics, electric-current, conductors, metals
Title: Why is the heat flow in metals slower than the current flow? When we apply a voltage across a metallic conductor, the current starts to flow almost instantaneously. But when a temperature difference is established across the same conductor, the flow of heat is much slower. It takes larger time for the heat to reach from one end to the other than the current. Why is this so? The current flows almost instantaneously because it is driven by an electric field which appears across the conductor almost instantaneously (near the speed of light). All electrons in the conductor are set into motion by a chain reaction. Collectively they all move through the conductor at what is called the drift velocity at the same time.
By contrast, heat transfer by conduction requires the transfer of energy by collisions between particles in the material that starts at the high temperature end of the conductor and progresses gradually to the low temperature end of the conductor. In the case of metals, the particles are primarily electrons.
Hope this helps.
The following is multiple choice question (with options) to answer.
When does electricity flow through a conductor? | [
"when it's outside around lighting",
"when it's attached to a battery",
"when it's attached to a human",
"when it's near a light bulb"
] | B | sending electricity through a conductor causes electricity to flow through that conductor |
OpenBookQA | OpenBookQA-78 | java, timer, benchmarking
Title: A simple Java class for implementing code stop watches - follow-up I have received a nice answer for this post. Now, it is my attempt for some improvement:
package net.coderodde.time;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;
/**
* This class provides easy-to-use means for measuring elapsed time.
*
* @author Rodion "rodde" Efremov
* @version 1.6 (Feb 12, 2019)
*/
public final class StopWatch {
private boolean isMeasuring; // false by default.
private long startTimeMillis;
private long markTimeMillis;
private final List<Long> memory = new ArrayList<>();
/**
* Starts measuring time.
*/
public void start() {
setImpl(true);
}
/**
* Stops measuring time.
*/
public void stop() {
setImpl(false);
}
/**
* Resets the starting time to the current moment.
*/
public void reset() {
setImpl(true);
}
private void setImpl(boolean expectedStatus) {
if (expectedStatus) {
checkMeasuringStatusIsOff();
} else {
checkMeasuringStatusIsOn();
}
startTimeMillis = System.currentTimeMillis();
markTimeMillis = startTimeMillis;
isMeasuring = !isMeasuring;
memory.clear();
}
/**
* Marks current time for future calculation of lap times.
*/
public void mark() {
checkMeasuringStatusIsOn();
markTimeMillis = System.currentTimeMillis();
}
/**
* Returns the time elapsed from beginning of the current lap.
*
* @return the lap time.
*/
public long lap() {
checkMeasuringStatusIsOn();
long now = System.currentTimeMillis();
memory.add(now);
long saveMarkTimeMillis = markTimeMillis;
markTimeMillis = now;
return now - saveMarkTimeMillis;
}
The following is multiple choice question (with options) to answer.
I can use a stopwatch to track | [
"The number of freckles I have on my back",
"How long the road is",
"My weight loss in 6 months",
"how many marshmallows I can eat in 10 minutes"
] | D | a stopwatch is used to measure time |
OpenBookQA | OpenBookQA-79 | ### Show Tags
29 May 2017, 10:14
1
60*3 = 180
+
24*5= 120
120+180 =300
Speed= Distance/Time = 300/8 = 150/4=75/2=37.5
Manager
Joined: 03 Aug 2017
Posts: 103
Re: Jim travels the first 3 hours of his journey at 60 mph speed and the [#permalink]
### Show Tags
09 Dec 2019, 07:43
Bunuel wrote:
Jim travels the first 3 hours of his journey at 60 mph speed and the remaining 5 hours at 24 mph speed. What is the average speed of Jim's travel in mph?
A. 36 mph
B. 37.5 mph
C. 42 mph
D. 42.5 mph
E. 48 mph
tIME = 3 S=60 d=ST = 60*3 =180 miles
time 2 = s=24 d st = 120 Miles
Total d = 180+120 =300
Total time =5+3= 8
Total Avg speed = Total Distance / total time = 300/8 = 37.5 or B
Re: Jim travels the first 3 hours of his journey at 60 mph speed and the [#permalink] 09 Dec 2019, 07:43
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The following is multiple choice question (with options) to answer.
If John were going to the store, how would he measure his trip? | [
"kilometer",
"centimeter",
"decameter",
"meter"
] | A | kilometers km are a unit used for measuring distance generally used for values between 1 and 50000000 |
OpenBookQA | OpenBookQA-80 | electricity, electric-circuits, electrons, electric-current, charge
Title: Electrons in an electric circuit , its movement and power delivered Does an electrical appliance convert electrons into its respective work , I mean is electron being consumed by appliance (say bulb ) and then this mass gives us energy.
or the same number of electron , just revolve around the circuit, then from where does power comes from, Electrons have charge and so when there is a potential difference across a circuit, this charge moves through it. In an incandescent light bulb, there is a high resistance, meaning that there are many atoms with which the charges collide, transferring some of their kinetic energy. No electrons are being "consumed" by the light bulb, i.e. the number of electrons in the circuit does not change. The ability of the charges to do work is because of a potential difference, which can be achieved through a number of means, e.g. using voltaic cells or electromagnetic induction.
To gain a better idea of why potential difference moves charges, consider two isolated point charges of opposite charges, one positive and one negative. If you pull the negative charge away from the positive one, you are doing work on it in the form of potential energy, as you are opposing the electric field of the positive charge. If you let go, the negative charge will convert this potential energy into kinetic energy, as it is attracted to the positive test charge. A potential difference across a circuit, albeit simplified, essentially does this – it brings electrons from a higher potential to a lower potential, converting potential energy into the kinetic energy in the process.
The following is multiple choice question (with options) to answer.
A man plugs his television into an outlet behind a cabinet. He sees that the television may now be turned on so that he can watch his favorite show. The man knows that by hooking the t.v. cord into the outlet | [
"he completed a lap",
"he made a good deal",
"he invented new circuits",
"he completed a circuit"
] | D | when an electrical conductor is plugged into an outlet , a circuit is completed |
OpenBookQA | OpenBookQA-81 | heating-systems
Comparison between the two.
So you can see that, while you use more efficiently the primary energy with the steam boiler, if the electricity you get is from a renewable source then the ceramic might be more environmentally friendly.
Of course, I avoid going into the discussion about carbon emissions, or the total impact on the environment (e.g. consider if your electricity came from nuclear). That makes the problem even more complex.
A Better solution
If you live in a relatively warm climate (i.e. you don't get temperatures under 0 more that a few days per year), a better alternative for electrical power can be a heat pump.
The difference with heat pumps, is that they don't use the electrical energy directly for heating. (Simply put) What they do is they use the electrical energy to mechanically move an arrangement of pumps/compressors/condensors to pump heat energy from one side of the wall to the other. Heat energy that would not usually be inclined to flow towards that direction. More specifically, they take heat from the colder environment and pump it inside a warmer room.
That process, in ideal conditions, is very efficient. For example, for one unit of electrical energy you can nowadays move up to 4 units of heat energy. That ratio of useful energy to energy expended is the basic formula for the famous COP - Coefficient of performance. In this specific example COP would be 4.
So in ideal conditions, if you used 100 units of fossil fuel, and got 35 units of electrical energy, in theory you could get 140 units of heat energy pumped in your room.
Of course, there are limitations. E.g. at cold climates using a heat pump would create ice/frost on the heat pump, which ultimately would lower significantly the COP.
The following is multiple choice question (with options) to answer.
Which type of energy is the most environmentally friendly? | [
"Coal",
"Petroleum",
"Natural Gas",
"Sunlight"
] | D | solar energy is a renewable resource |
OpenBookQA | OpenBookQA-82 | It could not be only square because if it is square then it is a rectangle too and if it is rectangle then it is trapezium too. And I don't think so that it is multiple correct type. But it is sure that it cannot be a triangle as it is a four sided figure.
Yes you were right. By the given information it can't be proved that it is rectangle or square so the answer I think must be F.) trapezoid
One might also point out that a square is also a special case of trapezoid, rectangle, rhombus, quadrilateral and parallelogram, so any of those answers would technically be correct, assuming the object in question was, indeed, a square.
However, I think what everyone is missing is that while in a classroom the "right" answer is the one the teacher is looking for, even if that answer isn't the "correct" one... I've found in my experience that teachers can be obstinate, and aren't likely to be pleased by being corrected by a student in front of the class. Better (for ones academic success) to do so after class and let the teacher correct him/herself in a future class, or not...
• The problem wasn't to have the teacher corrected in the first place but that the student with the right answer was humiliated in front of the class. – JFS May 20 '15 at 18:27
The following is multiple choice question (with options) to answer.
Which form can be made into a triangle? | [
"ice",
"steam",
"water",
"salt water"
] | A | Matter in the solid phase has definite shape |
OpenBookQA | OpenBookQA-83 | • I understood the question differently. The answer to the puzzle is irrelevant: The fact that D has more information than C still gives an "educated blind" guess by D lesser chances of being right than an "educated blind" guess by C (assuming OP's calculations etc are correct). Normally one would expect that the higher information you have, the better your chances of making a guess in general... Jun 24, 2011 at 21:44
• @Aryabhata: that's exactly what I meant to ask. I've updated the question to clarify. Jun 24, 2011 at 21:47
• @shambulator I realized this after my initial answer - I've edited this answer now to reflect that. Sorry! Jun 24, 2011 at 21:53
• not to worry, the conclusion in your amended answer and the analogy leading up to it have given me a lot to chew on :) Thanks for answering! Jun 27, 2011 at 19:38
With the aim of making this question/answers post self-contained, I've inserted the image from the linked puzzle, below, followed by the solution given in that link.
Four Men and a Hat
Shown above are four men buried up to their necks in the ground. They cannot move, so they can only look forward. Between A and B is a brick wall which cannot be seen through.
They all know that between them they are wearing four hats--two black and two white--but they do not know what color they are wearing. Each of them know where the other three men are buried.
In order to avoid being shot, one of them must call out to the executioner the color of their hat. If they get it wrong, everyone will be shot. They are not allowed to talk to each other and have 10 minutes to fathom it out.
After one minute, one of them calls out.
Question: Which one of them calls out? Why is he 100% certain of the color of his hat?
This is not a trick question. There are no outside influences nor other ways of communicating. They cannot move and are buried in a straight line; A & B can only see their respective sides of the wall, C can see B, and D can see B & C.
Spoiler/solution, and see Steven's answer for clarification
The following is multiple choice question (with options) to answer.
who would see better through an underground tunnel? | [
"a boy with a pen",
"a man with a stick",
"a man with a spoon",
"a man with a candle and match"
] | D | a candle is a source of light when it is burned |
OpenBookQA | OpenBookQA-84 | And the odds only get better as the number of doors increases... :)
-
## protected by Ragib ZamanDec 18 '13 at 11:32
Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
The following is multiple choice question (with options) to answer.
There are now many more people because of | [
"efficient farming",
"more cities",
"computers",
"global warming"
] | A | the increase of something required by an organism has a positive impact on that organism 's survival |
OpenBookQA | OpenBookQA-85 | dna, cloning, dna-isolation
If you do this, regular freezers are not cold enough to prevent freezer burn. This is what happens when you put a steak in to the freezer, wrapped in plastic even it will shrivel up and start to dry out as the water in the ice starts to sublime out of the package (the dry air in the freezer basically sucks the water out of the food). If this happens to your animal tissue, its probably not going to revive.
Scientific labs use -80C freezers and liquid nitrogen storage because the water turns into a glass and all biochemical reactions are basically stopped. (besides drying out, the enzymes like DNAse are still nominally functioning in the cells at -20C and even simple bacterial cells don't live for more than a year at -20C, much less mammalian cells). For preserving cell lines, liquid nitrogen is much more preferred. I would say that properly produced cell lines can theoretically revive after indefinite liquid nitrogen storage.
So that's a quick answer. Sorry to be a party pooper - things could change quite a bit in the next 20 years, but we just don't know how much. popping a paw in a baggie or some DNA extract into the freezer might work, but its hard to say for sure.
As far as the choice of where the DNA comes from in the animal, its true that skin cell lines are often producing imperfect animals - the DNA may be modified in the skin in various ways that cause the animal to be smaller, weaker, or even deformed compared to the donor. At this time all the protocols I see (and i could be wrong) are skin cells. I would expect that there is a better tissue to preserve, but that might be just a guess at this point. Its likely that in the next 20 years the choice of cell line from the donor will change quite a bit as well.
The following is multiple choice question (with options) to answer.
Water in a sealed jar might do what when placed in the freezer? | [
"evaporate",
"break it",
"melt",
"run off"
] | B | when water freezes , that water expands |
OpenBookQA | OpenBookQA-86 | reaction-mechanism
It is generally said that reactants react so that they can achieve a
lower energy state. Then why does a reversible reaction occur in the
first place?
Good question. Remember that we can always add energy to make an unfavorable reaction proceed. For example, the sodium ion, which is isoelectronic with neon, is stable with a full octet of electrons. However, we can still take away more electrons. It just takes a rather sizable application of energy.
The following is multiple choice question (with options) to answer.
What causes a chemical reaction? | [
"mixing and heating edible items",
"putting water in a bowl",
"petting a small cat",
"rolling a ball on a floor"
] | A | cooking causes a chemical reaction |
OpenBookQA | OpenBookQA-87 | food-chemistry
popcorn (kernels)
honey (jar of)
sugar (most forms)
alcohol (spirits like vodka, whiskey)
dried beans, dried lentils
I would not be planning to eat any of these stored for 25 years myself. And in general I'd suggest testing the items before trying them after 25 years or more (if you feel you must).
I would not expect cans or glass or plastic bottles of soda to be in good shape after anything like 25 years. The plastic might not survive without degrading. The can and plastic might react with the liquid over that timescale and the glass would survive but I'd be less optimistic about a sugar laced chemical soup like soda or cola not undergoing some changes. Hard to say.
If you want more info on this try this website.
Will it be ok to drink it, if it won't explode?
I would not try it. At best it soda would be flat and possibly not taste the same (chemical changes over that timescale ?) and at worst it could actually be harmful.
Exploding seems very unlikely.
Also, what about Snickers or a hamburger in a ziploc package with air sucked out of it with vacuum cleaner?
Air isn't the issue. There are bacteria that will happily live (and increase in numbers) on what's in the food. Well, it is food, after all. There are bacteria that will survive refrigeration as well. Over the timescale you're talking about I'd say it's all bets are off territory.
So: will Snickers, Hamburger in a ziploc, Bottle (or can) of Cola, all not opened, go crazy in 25 years? In 50 years?
All of those could be dangerous over such a long time period, IMO. At the very least they'd taste bad and at worst they'd kill you if you consumed them.
If so, can they go out of their packages and ruin the contents of the time capsule? If not, will it be safe to consume one of them?
Depends on the packaging. Glass would last indefinitely baring physical force or extreme of hot and cold (which might possibly cause fatigue cracking). The other wrappers would last pretty well (structurally), but 25 years is way past their design intentions. It would be a dice throw.
The following is multiple choice question (with options) to answer.
What stores food for future use and is green? | [
"bacteria",
"trout",
"virus",
"tree"
] | D | usually plants store the food they produce for future use |
OpenBookQA | OpenBookQA-88 | thermodynamics, water, pressure, ice, freezing
Title: Why did my frozen water bottle explode when I opened it after it defrosted a bit? Last night I filled a 20 fl oz bottle (http://www.thenibble.com/reviews/main/beverages/soft-drinks/boylans-mash.asp) with lukewarm water from my tap. I filled the bottle pretty much to the brim, capped it, and put it in my freezer.
Today, I took the bottle out, and left it on the table in my far-too-hot room for 10 minutes or so. When I unscrewed the cap, water flew everywhere, like a can of soda that's been shaken up really intensely. What happened? Can anyone explain this? Water is an unusual substance in that it expands when it freezes. Evidently this expansion wasn't enough to burst the bottle in your case, but it left the bottle's contents under pressure. After you'd defrosted it for a while there was, presumably, some ice and some water in the bottle. Because the ice was taking up more volume than it did when it was water, the liquid water in the bottle was pressurised. I expect that the bottle's sides were bowed out slightly to accommodate the extra volume. When you unscrewed the cap, the pressure forced the liquid water out of the bottle. Essentially (I would guess) it was being pushed out by the slightly elastic sides of the bottle contracting back to their usual shape.
The following is multiple choice question (with options) to answer.
Filling a bottle full of water and then placing it in the freezer can lead to | [
"loosening of the bottle lid",
"deflation of the bottle",
"ice cubes in the freezer",
"bursting of the bottle"
] | D | when water freezes , that water expands |
OpenBookQA | OpenBookQA-89 | javascript, collision, canvas
// run loop
setInterval(loop, 20);
}); Haven't looked at the code in detail, but here are some thoughts on the overall structure:
Right now, there's some mixing of concerns and tight coupling going on. The engine calls update on the active block, but the block then calls back to the engine to check for collisions. In other words, the two are tightly coupled; they're dependent on each other, and its unclear where certain responsibilities lie.
The block is a pretty simple object, which can be reduced to simply being an x, y position, and a velocity. And it should probably stop there. The engine would be responsible for moving the block (the block object can do the calculations, though), checking collisions, accepting keyboard input, etc.. I.e. keep the block "dumb"; it doesn't need to know its context.
I'd also suggest making a similarly "dumb" grid object that the engine object can interrogate and instruct. I.e. the grid doesn't move blocks around, it simply keeps track of them for the engine. The grid could check for collisions, but it'd be up to the engine to ask.
Where exactly to draw the boundaries between the objects and their responsibilities is up to you (there are many ways to break it down), but the idea is to keep things decoupled when possible. I.e. blocks don't rely on a grid or an engine being there; the grid may or may not care about blocks being blocks, just that there's something in a given cell, etc.. Perhaps there are more things, you can extract and/or abstract and encapsulate in objects or constructors, while the engine sits in the middle acting as controller.
On a purely syntactical level, I'd move the methods of into the prototypes for the objects. That is, from this
function block() {
// instance variables ...
this.update = function () { ... }
}
to this
function Block() { // CamelCase since it's a constructor
// instance variables ...
}
Block.prototype.update = function () {
...
};
This will make it easier to do prototypal inheritance, as the methods will actually be prototypal.
The following is multiple choice question (with options) to answer.
What functions without contact between objects? | [
"weight",
"friction",
"opposites attracting",
"pressure"
] | C | magnetism does not require contact between objects to act |
OpenBookQA | OpenBookQA-90 | physical-chemistry, thermodynamics
In space, both the temperature and pressure are very low. That would put beyond the bottom left corner of the diagram, well within the ice field. So simply speaking, water would be ice.
However, there is the concept of vapour pressure. Any condensed material (just a fancy word for both solids and liquids) has that same material in the vapour around it. That's why you can smell alcohol, even though it's liquid as one example. That's why a puddle of water will eventually dry out even though it's below the boiling point of water.
The way vapour pressure works is that if you look on the phase diagram, for a certain temperature, the liquid-vapour and the solid-vapour lines have certain pressures associated with them. For example, if you look on 50 C, then the pressure on the curve is 10 kPa. Roughly speaking, this means that in atmospheric pressure, one tenth of the air (which is at 100 kPa) has to be water vapour. If it's any less, water will keep evaporating until it reaches that amount. On Earth, wind and diffusion will disperse the water so it will basically evaporate until there are no more liquid water left.
Now let's think what would happen in space. The temperature is very low, so the vapour pressure is very low. Thus, it should evaporate also in space. However, because the vapour pressures at such low temperatures are extremely low, you might end up with a situation where the gravitation of that ice blob is enough to overcome evaporation, so that will be an agonizingly slow process.
The following is multiple choice question (with options) to answer.
Which doesn't contain water? | [
"Sea of Tranquilitiy",
"Caspian Sea",
"Dead Sea",
"Caribbean Sea"
] | A | the moon does not contain water |
OpenBookQA | OpenBookQA-91 | ecology, mycology
Title: Is there an antagonistic association between Penicillium and Aspergillus? Some Aspergillus species appear to like walnuts. My question concerns the association of Penicillium and Aspergillus. No sooner does Aspergillus colonize a walnut (or some other challenging carbon source) than Penicillium seems to move in, eventually killing the Aspergillus colony.
A totally unscientific guess is that Aspergillus is a good colonizer and Penicillium a good opportunist and that this is a common pattern with these two species. Is there any science in this direction? I do recall a sort of well-known picture from an old text in which Penicillium is shown more or less strangling a species of Aspergillus. I didn't think about it much at the time.
The image attached is not very incriminating but the theme is the same. Penicillium are the green hand-like structures strewn about the clover-like Aspergillus. Foot-cell of the latter cropped.
This seems like a simple question but a quick search doesn't reveal a lot, I think in part because this would generally come up as a contamination issue. It is hard to find any articles on the association between Penicillium and Aspergillus species, although they are both considered two of the most common mold species found indoors.
In this study, the most prevalent spore types detected in both the indoor and outdoor air samples were generally from the Penicillium/Aspergillus group [...] these findings are qualitatively similar to those observed in other geographical locations, confirming the ubiquitous nature of these fungi.
Although these genera seem to be found commonly, it also has to do with environmental factors, and the relative humidity of the area as well.
Geographical location, climate, and short-term meteorological
conditions are responsible for outdoor types and levels of fungal
spores.
As for the association and apparently colonization/opportunistic behaviour of the genera, it seems like there are not any associations between the two, unless perhaps environmental conditions are subject to changing, and different mold species have different moisture/temperature thresholds, although again these mold groups tend to be generalists and do well at a wider range of environmental conditions than other fungi.
The following is multiple choice question (with options) to answer.
Fungi | [
"can do their food chain jobs without ingestion",
"act as predators in the food chain",
"are always safe to ingest",
"occupy the top of the food chain"
] | A | In the food chain process fungi have the role of decomposer |
OpenBookQA | OpenBookQA-92 | thermodynamics, pressure, everyday-life, fluid-statics
Title: Holding one's breath while scuba diving Recently when I went scuba diving, the instructor told me that it would be extremely fatal to a scuba diver to hold his breath during the dive. I searched up on the internet and came across Boyle's law ($PV = c$). However, I am still unable to comprehend the explanation. Perhaps someone can provide me with a more detailed and easier to understand explanation? This is the problem, the deeper you go, the higher the pressure, say that initially you're at a depth where the pressure is $P_1$. You then breath in a volume $V_1$ or air and hold your breath while swimming up.
You do so until you reach a depth where the pressure is lower $P_2 < P_1$, according to Boyle's law
$$
P_1 V_1 = P_2 V_2 \tag{1}
$$
or equivalently
$$
V_2 = \left(\frac{P_1}{P_2}\right)V_1 > V_1 \tag{2}
$$
That is: the air in your lungs is going to expand which may cause some serious issues. For instance, bubbles can go into your blood stream, or they can rupture.
To give you a quick example, if you inhale at a depth of $10$ m ($P = 2$ atm), and them hold your breath up to the surface Eqn (2) tells you that your lungs should increase twice its size! Look at this link
The following is multiple choice question (with options) to answer.
Compared to a regular swimmer, a scuba diver deals with more | [
"heat",
"pressure",
"water",
"air"
] | B | as an object descends into water , the pressure on that object will increase |
OpenBookQA | OpenBookQA-93 | thermodynamics, statistical-mechanics, entropy
Systems that persist over some duration of time, including living things, have to persist stochasticity in the state dynamics to remain with some distribution of states in which we still identify them as the thing they are. For example, if the particle configuration of a dog would change out of the distribution of particle configurations that we consider to be dogs, we would not call it a dog anymore.
I think your question may be what is known as Schrödinger's "paradox":
The following is multiple choice question (with options) to answer.
What is an example of the fact that a thing is dead once it dies after having previously lived? | [
"a small squirrel falls from a tree and breaks its leg",
"a panda stops eating and falls into a coma",
"a dog is paralyzed and is unable to move",
"a vibrant cat is deceased after being hit by a car"
] | D | if a living thing dies then that living thing is dead |
OpenBookQA | OpenBookQA-94 | optics, atmospheric-science, weather
Title: Explanation for an unexpected rainbow Yesterday, I observed an unexpected rainbow in the sky. There was no forecast for rain, neither was it raining anywhere nearby. I have been trying to find an explanation but don't seem to find any. Can someone please explain what this rainbow is?
Note:the colours were way more vivid as compare to the picture I have taken These are tropospheric Iridescent Clouds
According to AtmosphericOptics:
When parts of clouds are thin and have similar size droplets, diffraction can make them shine with colours like a corona. In fact, the colours are essentially corona fragments. The effect is called cloud iridescence or irisation...
The usually delicate colours can be in almost random patches or bands at cloud edges. They are only organised into coronal rings when the droplet size is uniform right across the cloud. The bands and colours change or come and go as the cloud evolves...Iridescence is seen mostly when part of a cloud is forming because then all the droplets have a similar history and consequently have a similar size.
I've saturated the image so the interesting part can be appreciated
And here you have a very similar observation I quickly found by google image search:
The following is multiple choice question (with options) to answer.
Thunder clouds are | [
"filled with beautiful music",
"of a significant weight",
"the color light pink",
"take 10 years to form"
] | B | clouds produce rain |
OpenBookQA | OpenBookQA-95 | newtonian-mechanics, forces, rotational-dynamics, torque
Title: Falling off a chair, how best to save yourself If I consider a man sitting on an office chair that reclines backwards iff you lean backwards.
What could be done to prevent hin from falling?
a) raising his legs till they are parallel to ground.
b) bring the feet closer to himself(as close as possible) and press them down on the ground.
Please don't suggest any other way. I want to compare these two. Ie, which is better.
Argument in favor of a)
The center of mass moves away from the rear end of the chair towards the forward end of the chair so torque of weight will restore the chair. (This works if you are in an armchair, and are rocking to and fro).
However, intuition says contrary to this. I feel scared of falling If I do this.
Argument in favour of b)
Intuition favours this. Normally when we talk about balancing our body, what "feels right" is better for the safety. So, I can not say what is right. Please explain what your views are in this case. Again, the purpose of this question is not to ask what should be done, only what is better to do out of these two choices. This sounds to me like an experimental question (but be careful not to hurt yourself!).
Note that since you want the chair to rotate forwards towards the ground, you'll want to consider the direction of the angular momentum your motion introduces. If you kick your legs out rapidly, not only does the weight of your feet tilt the chair forward, but the angular momentum of your legs moving upwards in front of the chair will tend to be balanced by an upward motion of the back of the chair. However, if you're tilted too far backwards before you kick out your legs, you'll get a second and opposite angular momentum kick once your knees are straight, which might send you over backwards.
This is why the best approach is to stick out your legs and pinwheel your arms.
The following is multiple choice question (with options) to answer.
If someone is experiencing frequent falls | [
"they should move out of their house",
"they should just stop trying to walk",
"they should try wearing slicker bottomed shoes",
"they should try putting down carpet or throw rugs"
] | D | as the smoothness of something increases , the friction of that something will decrease when its surface moves against another surface |
OpenBookQA | OpenBookQA-96 | astronomy, astrometrics
Depending on how much "around the limb" you can see in each direction, this gives you an offset from the sub-lunar point from which you can determine the position of the photographer.
The amount of "extra" moon you can see is going to be very small and the best accuracy you can achieve will probably depend on the resolution of the image. Higher resolution images will give you better results. I have no idea how accurate it would be that that would be the method to do the calculation.
Now if you had stars in the image as well as the Moon, you could do even better. Given a good sky atlas and the date and time of the observation, you could match up the starfield behind the Moon. Again depending on the resolution of the image and how accurately you could measure stellar positions, you could then determine where on the Earth you would have to be at that time to have the Moon exactly in that position relative to the background stars. If you moved a little in any direction, the Moon would move relative to the background stars so this would constrain you quite a bit.
I don't know of any programs that would do this for you. The information exists, and you could work it out, but it might be easier to just send the photographer an e-mail and ask them where they were when they took the picture. :) That would probably be more accurate in any case.
The following is multiple choice question (with options) to answer.
It is easiest to get a clear photo of the moon by | [
"using a large magnifying glass",
"using a telephoto lens",
"using a telescopic lens",
"looking through a microscope"
] | C | as the size of an object appears larger , that object will be observed better |
OpenBookQA | OpenBookQA-97 | pressure, home-experiment, atmospheric-science
Title: Atmospheric pressure experiment using a cup with a fluid to hold a glass plate When I was in high school, my teacher did an experiment to show the power of atmospheric pressure.
Experiment:
Prepare a glass bottle, fill with water, put a glass plate on the bottle, make sure there is no air in the bottle, just water. Hold the glass bottle and plate, and invert them. Slowly, release the hand which hold the plate. Because the atmospheric pressure, the glass plate will not fall down.
The following is multiple choice question (with options) to answer.
Filling a glass with markers for cup amounts on it would be | [
"seeing how much data is left on a phone",
"a part of making chili",
"a way to consider getting something",
"a way to collect data"
] | D | An example of collecting data is measuring |
OpenBookQA | OpenBookQA-98 | 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.
Winter snows follow Autumn's falling leaves by | [
"three months",
"three days",
"three years",
"12 months"
] | A | a new season occurs once per three months |
OpenBookQA | OpenBookQA-99 | 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.
The way that squirrels put away food during the cool season ensures that they | [
"survive",
"eat",
"live",
"grow"
] | A | squirrels gather nuts in the autumn to eat during the winter |
OpenBookQA | OpenBookQA-100 | Going further, this MO question has a hint about how to make an example $q$ that is $C^\infty$.
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The following is multiple choice question (with options) to answer.
An example of a consumer would be | [
"a deer munching grass",
"a plant beginning to photosynthesize",
"a squirrel eating a bug",
"a wolf eating a deer"
] | A | consumers eat other organisms |
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