Wikipedia:Reference desk/Archives/Science/2012 May 30

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May 30

Calories consumed during periods of intense activity

How many calories per day are typically consumed by a person (say an average-sized, fit guy) training for a marathon? Training for an Olympic swimming event? A triathlon or iron-man competition? I'm talking about high-intensity activities, where one isn't trying to gain weight (so, not weightlifting or its ilk). Now, roughly how many calories were consumed daily by Bobby Fischer and Boris Spassky during their chess competition? LadyofShalott 01:43, 30 May 2012 (UTC)

For athletes anywhere from 3500 Kcal/day up to 10,000 Kcal/day. Normal people will need about 2500 Kcal/day, one hour per day exercise will add 1000 Kcal to the energy needs and one hour per day is pretty much the lower limit of what you need to do to be able to perform at a decent amateur level. Michael Phelps is a example of someone near the upper limit of 10,000 Kcal/day, see here. Count Iblis (talk) 01:58, 30 May 2012 (UTC)

That's exactly what I needed to see - thanks! So I can rest assured that the crazy guy who claimed to me he'd eaten about 12-14,000 Kcal/day all his life (some of that time running about 4 miles/day) really is as crazy as I assumed. I asked about the chess players because he specifically mentioned that they'd comsumed such quantities during their tournament, and he'd eaten his highest amount when he was working on his invention. (I didn't learn what said invention was.) LadyofShalott 02:21, 30 May 2012 (UTC)

Four miles a day is not nearly enough to require that much food. Even the explorers who walked to the south pole from the coast of Antarctica were only eating 8,000 Kcal/day. There are certainly people who eat far more. There are documented individuals who consume in excess of 30,000 Kcal/day (the absorption of calories by the body is actually quite inefficient at that level), but all of them have one or more mental issues, and are quite obese. Someguy1221 (talk) 02:44, 30 May 2012 (UTC)

Thanks, this was not a fat person. You've both given me some good perspective on just how "off" the claim was. LadyofShalott 02:59, 30 May 2012 (UTC)

Goethian Optics

In his Theory of Colors, Goethe criticized Newton's theories of light and color. As far as I can tell, the theory he developed to explain the observations he made are nonsense. But that said, is there a way to make his observations compatible with Newton's ideas (in particular, light coming out of a prism, as in the picture in the article)? My guess is that a combination of Newton and the complexity of the human visual system can explain anything, but has a detailed analysis been performed? 65.92.6.118 (talk) 02:57, 30 May 2012 (UTC)

I believe Goethe's theory of light will always fail under modern (or even late 19th century) understanding of light due to his insistence on the physicality of darkness. We know well today that true darkness or blackness is the absence of detectable electromagnetic wave emissions off a surface, rather than "the polar opposite of light". And we further know that darkness does not interact with light to produce colors. What Goethe saw in his experiment was not an interaction of light and dark at the border of a beam projected through a prism, but the selective removal of wavelengths near the border. So once again, while his ideas were intriguing at the time, you have to forget the last 140 years of electrodynamics for them to be compatible with anything. As for Newton's own ideas, the article on Goethe's book doesn't go into detail on how Newton explained the physicality of the colors themselves - it merely mentions that he theorized they were all present in white light. In fact, Newton further theorized that light existed as rotating particles in a continuum of possible rotational frequencies. Each frequency corresponded to a distinct color, and the refractive index through a material boundary varied with rotational frequency. Given this fuller theory, it is impossible to merge Newton's and Goethe's theories without leaving out something essential. Someguy1221 (talk) 03:38, 30 May 2012 (UTC)

Oh, sorry, I thought you were asking to merge the theories, and here I reread and see that you were asking to explain his observations. But I did sort of answer that. But anyway, I think a fuller explanation only requires there things. The easiest experiment to explain is the creation of colors at the border of light and dark. As I said, this is due to a selective removal of wavelengths near the border. What you can imagine is that the light is passing through the prism as a column, and the colors are being separated into distinct columns. If the projection plane is too close to the prism, those columns overlap. In the center, all color-columns overlap, and you see white. But near the border, you are seeing just the edge of a single column, giving the appearance of red or violet. As you move the projection surface further away, the columns separate more, and the colors become more apparent. With regard the change in the color of light passing through a turbid medium, this may just be an effect of the absorption spectrum of the medium he was using (the article doesn't mention what its makeup was, merely that it was turbid). If that is the case, it simply means that his medium was absorbing the blue out of sunlight ever more at increasing concentrations, giving rise to a yellow or orange color. Now, with regard the blueness of and illuminated medium through which you are viewing darkness, there is an excellent experiment you can do outside your own home! Just look up at the sky during the day. It's blue. But you know that beyond that blue is actually darkness. What you are seeing is diffuse sky radiation. Basically, the blue wavelengths of light are being disproportionately scattered back toward your eye as sunlight passes through the atmosphere. This concept also applies to other media besides air, although you typically have to look through several meters to see a significant effect, and the color may vary with the material. Someguy1221 (talk) 03:52, 30 May 2012 (UTC)

"But near the border, you are seeing just the edge of a single column, giving the appearance of red or violet. As you move the projection surface further away, the columns separate more, and the colors become more apparent. "

Sorry, could you explain this a little more? Photos like the one in the dispersion (optics) seem to say that colours are always quite separated when they leave the prism. 65.92.7.168 (talk) 02:31, 31 May 2012 (UTC)

The first picture in the wiki dispersion article is not a photo, but a diagram. Whoever drew the diagram took an easy path and just drew specific colours, rather than the gradual variation that actually occurs. The second photo is of the spectrum of a compact flourescent lamp. You can be misled by such photos, because what such lamps emit is NOT white light, it is what looks like approximate white light to the human eye, and is not a continuous spectrum. It is a limitted number of specific colours. You cannot separate out what isn't there in the first place. To use a prism to show that white light comproses a continuous spread of wavelengths/colours, you must use a true white source, for which a back body radiator, such as the sun or an incandescent light, is a usable approximation. Ratbone124.182.150.22 (talk) 02:44, 31 May 2012 (UTC)

A wayyy better (re: more accurate) diagram can be seen about halfway down this page. Basically, in Newton's time there was no method for producing bright light in a laser-like beam. For color-splitting experiments, you instead put a circular aperture over a window and used the sun. What would come out is a relatively even column of approximately white light. For the image you pointed to, you can see that instead of a column of light entering the prism, it is a very thin beam. If you had access to a sufficiently thin beam, then yes, the colors would be separated immediately. If you like that concept, think of the column of light as a bunch of thin beams entering the prism at slightly different locations. When you're too close to the prism, the reds coming off of some beams overlap with the greens and blues coming off of some other beams. Someguy1221 (talk) 05:36, 31 May 2012 (UTC)

Not a wayyy better diagam at all. Not only does it show discrete colours where there should be a continuous spectrum, it shows no splitting at all within the prism. The separating out of colours in a prism is due to the fact that the refractive index of typical prism glass (or plastic etc) is a function of wavelength, ie colour. This means that some colour spreading occurs within the prism. At least our wiki articles get that right. And the 3rd diagram on Someguy's link is nonsense. Wickwack58.167.248.70 (talk) 11:34, 31 May 2012 (UTC)

Okay good, I thought the discrete color separation thing was fishy. But I still can't see why there would be white light coming out of the prism when the projection plans is close to the prism. 65.92.7.168 (talk) 15:47, 31 May 2012 (UTC)

The colours are only well separated when they leave the prism if the input to the prism is a narrow beam of light. Goethe illuminated the prism with a wider beam of light. With a wider beam, the colors come out at the same angles as with a narrow beam, but close to the prism the colors overlap. In the middle of the beam, green light from the middle of the input beam overlaps with red light from one side of the input beam and violet light from the other, and you get white light. Each color light propagates with a distinct angle, but light from different parts of the input beam start at different initial positions in the plane perpendicular to the beam's path. Because of this, different colours can overlap near the prism.--Srleffler (talk) 17:30, 31 May 2012 (UTC)

Perfect, thank you. 65.92.7.168 (talk) 18:33, 31 May 2012 (UTC)

2867 Šteins — common-noun nomenclature

Craters on 2867 Šteins are named for precious stones, and have been given the English-language names of these stones, e.g. Diamond, Opal, Jade. Are there other similar examples of solar system nomenclature where English-language common nouns have been officially assigned to features or objects?--Cam (talk) 04:52, 30 May 2012 (UTC)

I couldn't find any other examples of English common nouns featured on the USGS's list of "Categories for Naming Features on Planets and Satellites". ---Sluzzelin talk 01:46, 2 June 2012 (UTC)

Polar oceanic climate?

Since the talk page of Köppen climate classification is not very active, I am posting here. Where does Macquarie Island, which has average temperatures in the 1–9 °C range year-round, fall under the Köppen system? No type on that page seems to fit this model. GotR ^Talk 08:05, 30 May 2012 (UTC)

Why would the Tundra climate (ET) not fit the model? Condition is that the warmest month average is between 0 and 10 degrees Celsius. - Lindert (talk) 08:20, 30 May 2012 (UTC)

Most tundras regularly experience temperatures much colder than Macquarie's record low, and the island averages above freezing at night in its "winter". Köppen does distinguish between continental and oceanic subarctic, though. GotR ^Talk 09:08, 30 May 2012 (UTC)

It sounds like it's maritime temperate/oceanic to me. It narrowly misses the 10C threshold, but climate classification is far from an exact science. The key feature is that it has a very narrow temperature range, due to the moderating effects of being surrounded by ocean. That fits the spirit of maritime temperate, even if the temperatures don't quite fit the letter of the definition. --Tango (talk) 11:26, 30 May 2012 (UTC)

In strict terms it's a Koeppen ET climate. The Australian government calls it "extreme oceanic", which is a good description but as far as I know is not a formal classification. The overall character of the climate is more like the Cfc classification (which it only misses by a degree in one month) than ET. A good illustration of the arbitrary nature of climate classification. Short Brigade Harvester Boris (talk) 01:02, 31 May 2012 (UTC)

Birds that humans can ride?

There's the ostrich, emu and the mute swan. Are there any others? --95.148.107.232 (talk) 08:53, 30 May 2012 (UTC)

If a human tried to sit on a poor mute swan (only 12kg and about as tall as swans go), he would squash the life out of it. Wickwack60.230.210.162 (talk) 10:23, 30 May 2012 (UTC)

And I'd have serious doubts about riding emus too. (Have you seen one?) So, to the OP's question, no. HiLo48 (talk) 10:33, 30 May 2012 (UTC)

I saw a Chinese circus act in the late 1990's which featured a goose pulling a cart, in which sat a driver. I thought it very cruel when I saw it (and I still do).--TrogWoolley (talk) 11:05, 30 May 2012 (UTC)

See this attempt to ride an emu. An adult would have no luck. A child might get away with it, but there'd be safety issues preventing such an attempt. -- ♬ Jack of Oz ♬ ^{[your turn]} 01:51, 3 June 2012 (UTC)

Elephant bird? Extinct now, but alive until relatively recently in human history. --Mr.98 (talk) 12:37, 30 May 2012 (UTC)

However, riding an ostrich seems to be possible (see YouTube: Ostrich Riding); allthough why anyone would want to, remains unclear. Alansplodge (talk) 12:55, 30 May 2012 (UTC)

Since any answer is presumably restricted to ratites, I think the answer must be no.--Shantavira|^{feed me} 16:05, 30 May 2012 (UTC)

The Cassowary is big enough but they lack the temperament to be messed with. SkyMachine ⁽⁺⁺⁾ 21:55, 30 May 2012 (UTC)

Premature babies could be carried by a wide variety of birds. Or are they not human? 101.173.42.164 (talk) 10:05, 31 May 2012 (UTC)

Storks even. However it depends on how you define "ride". SkyMachine ⁽⁺⁺⁾ 10:24, 31 May 2012 (UTC)

There are many stories besides the stork about people flying with the help birds. For example, The Little Prince has probably ridden many migrating birds at once; Baron Münchhausen recounts of the inhabitants of the Moon riding enormous vultures to war; some unknown guys in the József Attila poem “Indiában, hol éjjel a vadak” have tried to fly a chariot with eagles harnessed to it; Nils Holgersson has ridden on geese (though he was shrunk down at that time); Simonyi óbester has flown using birds in Móricz Zsigmond's novel Légy jó mindhalálig, etc. Apparently the trick in riding birds is either you need to be very light, or you need to harness more than one bird for a single bird isn't strong enough. Of course, in some of these stories it's questionable not only whether harnessing birds counts as “riding” them, but also whether the rider is human: the natives of the Moon in Baron Münchhausen's story are definitely not human. – b_jonas 12:35, 31 May 2012 (UTC)

Hmm wait, this is the science desk, not the humanities desk. – b_jonas 10:33, 1 June 2012 (UTC)

Woken up during non-REM sleep, i feel tired, why?, prevention?

When WAKED during NON-REM sleep, i feel tired in the rest of my wakefullness. in other words - someone wakes me in NRs? = will feel tired all day. (when waked in REM, feel active all day).

what is the name, mechanism, and possible prevention to this thing? thanks. — Preceding unsigned comment added by 79.177.180.234 (talk) 11:20, 30 May 2012 (UTC)

How do you know where you were in your sleep cycle? If you've been to a sleep clinic to have your sleep patterns analysed (which is really the only way you could know), then you should be asking the doctors there. If you haven't, then I would doubt the accuracy of your analysis. The article, sleep inertia, may be useful to you, but that shouldn't last more than a few minutes. --Tango (talk) 11:30, 30 May 2012 (UTC)

How to get hydrogen from electrolysis into a balloon?

Some time ago I tried to fill a small plastic bag with hydrogen obtained from electrolysis, but this didn't work. I put some sodium hydroxide in water and electrolysed that using a 40 volt DC power source. I measured the current, it was 0.1 amps. I had to make sure it didn't exceed 0.1 amps, to prevent the transformer from overheating, I did that by putting small amounts of sodium hydroxide in the water until the current was just below 0.1 amps.

The negative electrode was wound into a coil inside a small plastic cylinder. I attached this to the opening of a small plastic bag and then made sure it was sealed tight. The idea was that the hydrogen would collect into the bag. With 0.1 amps, this should happen at a rate of about 1 liter per day.

However, after one day, I didn't see any signs that the bag had inflated. So, what is going wrong here? Count Iblis (talk) 17:47, 30 May 2012 (UTC)

The "inside a small plastic cylinder" part confuses me. You need both electrodes to contact the water directly and have a direct electrical path from one to the other. If this plastic cylinder prevented that, this would be your problem.

Also, before trying to collect any gas, leave the collection balloon off, and see if any bubbles form (a few air bubbles will form in any case, but a continuous stream of rising bubbles means it's working). You could also use an electrical meter to see if any current is flowing (break the circuit and touch one end of the circuit with one probe and the other end with the other probe). StuRat (talk) 18:27, 30 May 2012 (UTC)

The best way I think would be to use some kind of a Hofmann voltameter, this way the oxygen and hydrogen is collected at the top of the seperate tubes. Once you see you have a decent amount of hydrogen collected, open the valve and collect it. - Lindert (talk) 18:45, 30 May 2012 (UTC)

StuRat, the cylinder is submerged in the water, and I can measure a current of 0.1 amp. Also I can see bubbles, the water changes color after a while (after one day it is a dark smelly mess). Somehow the gas isn't collecting in the bag. Lindert, yes, if I can make something similar to a voltameter, that would be an improvement. But it's not clear how I can make something like that with the stuff I have available, though. Count Iblis (talk) 19:54, 30 May 2012 (UTC)

Hydrogen diffuses (or maybe effuses?) quickly through a balloon wall, so my guess is that the same may be occurring with the plastic bag. Hydrogen molecules are very small and fast, so they diffuse through a thin solid like that more easily than other gasses do. Red Act (talk) 20:14, 30 May 2012 (UTC)

Very good point. When I did this in middle school, I used glass. Didn't collect much hydrogen, or very pure (due to the electrodes and electrolytes), but it was definitely there :) SemanticMantis (talk) 20:58, 30 May 2012 (UTC)

Plastic bags can work. My brothers made a "hydrogen bomb" out of a dozen garbage bags filled with hydrogen for one 4th of July. Made a nice deafening boom. However, maybe plastic bags are not all the same in this respect. StuRat (talk) 22:41, 30 May 2012 (UTC)

Proper electrolysis of water should generate hydrogen and oxygen - no place for a "dark smelly mess". Whatever your electrode is, it must be undergoing some electrochemical reaction that is replacing H+ as the acceptor for the electrons. Wnt (talk) 22:48, 30 May 2012 (UTC)

Oh, and StuRat, as this appears to be a real-life exercise, let's be clear that we're helping a valued colleague set up a basic science demonstration, not conspiring to produce an explosive device! Had the OP suggested any such intention I would rather strongly have discouraged people from directly involving themselves. Also note that the "deafening" in that statement is not a rhetorical flourish, but a real danger. Wnt (talk) 22:51, 30 May 2012 (UTC)

I can't imagine a faster way on to a government watch list than posting "Totally not making a bomb here guys!" :D RunningOnBrains^(talk) 02:12, 31 May 2012 (UTC)

Agreed, "DON'T TRY THIS AT HOME, KIDS !" StuRat (talk) 23:07, 30 May 2012 (UTC)

In order to eliminate a leaking plastic bag from the list of possibilities, why not invert a glass jar over the electrode and see if you can collect gas inside it ? (A plastic jar would tend to float away and/or capsize.) StuRat (talk) 23:10, 30 May 2012 (UTC)

The dark smelly mess is undoubtably chlorine gas. Where is the water from? 203.27.72.5 (talk) 05:00, 31 May 2012 (UTC) Ok, I think I know what's going on here. The water you're using contains NaCl. You're also adding NaOH. The reaction scheme is as follows:
NaCl->Na⁺+Cl^-
2Cl^-->Cl₂+2e^-
Cl₂+H₂->2HCl
HCl+NaOH->H₂O+NaCl
The net effect is that you regenerate your reactants from your products and produce a little heat from the electrical energy. 203.27.72.5 (talk) 05:11, 31 May 2012 (UTC)

However, both chlorine and humid hydrogen chloride tends to eat through plastic bags and rubber balloons. Plasmic Physics (talk) 05:52, 31 May 2012 (UTC)

They also tend to stay in solution and react without ever getting to the plastic bag in any significant concentration. 203.27.72.5 (talk) 06:06, 31 May 2012 (UTC)

Also, you need to check your math regarding 0.1A gives 1 litre of gas/day.

${\text{Assuming}}H_{2}{\text{behaves as an ideal gas,}}$

$1mol_{H_{2}}=22.4L$

${\text{so }}{\frac {1L}{22.4L/mol}}=0.0446mol$

$2H^{+}+2e^{-}\rightarrow H_{2}$

${\text{so }}N_{e^{-}}=2N_{H_{2}}$

$N_{e^{-}}=0.0446\times 2=0.0892mol$

${\text{For 1 second,}}$

$0.1A=0.1C/1s$

$F=96485.3365C/mol$

$96485.3365\times 0.0893=8615C/L$

$8615C/L\times 0.1C/s=861.5s$

${\frac {861.5s}{60s/min}}=14.36min$

203.27.72.5 (talk) 06:05, 31 May 2012 (UTC) My mistake. Should be x10s/C not x0.1C/s. Then the units work out and it's 23.9hours for 1 litre. 203.27.72.5 (talk) 06:37, 31 May 2012 (UTC)

I wouldn't say chlorine gas is undoubtedly a dark and smelly mass. Doing the electrolysis on a tiny scale as a kid, I don't remember it as dark at all, though sure, it could react. But the metal in an improvised electrode could also react. Look up the reduction potentials for various electrochemical half-reactions for various metals, chlorine, hydrogen. Oddly, I don't see a table here, but [1] covers some basics. Stuff that really hates electrons, like lithium or potassium ion, has a negative potential, hydrogen ion has a potential arbitrarily defined as zero, and stuff like chlorine gas that wants to be chloride has a positive potential. I'm not sure which metal would react and how to release a dark and smelly mass, or whether it's the metal itself or an oxide coating, etc. (I'm a bit rusty on this and perhaps someone will spot an error here...) Wnt (talk) 23:47, 31 May 2012 (UTC)

You're not going to get too many volatiles from metals, which would be needed to account for the smell. Chlorine from NaCl is the only candidate as far as I can see. Also, because the voltage supplied is 40V, and pretty much all of the ions in solution have an oxidation/reduction potential less than that, everything will react. I don't know what the electrodes are made out of, but assuming it's copper, it will enter solution as $Cu^{2+}$. That might account for some of the colour, but chlorine makes a dark green/yellow and it stinks. 101.171.213.82 (talk) 06:06, 1 June 2012 (UTC)

Metals often contain sulfur or arsenic, and they will result in smells (arsine hydrogen sulfide) when hydrogen reacts with them. With an inert electrode material such as platinum or gold you should not get that problem. Graeme Bartlett (talk) 06:41, 1 June 2012 (UTC)

Moon tilting

I have noticed that when waxing moon rises, the southeast part isn't lit. When moon sets, the northeast part is non-lit, so moon seems to tilt during the day. Why does this happen? I have noticed this from 60 N latitude. — Preceding unsigned comment added by 88.113.124.190 (talk) 22:16, 30 May 2012 (UTC)

During one night, the main effect you are seeing is the earth's rotation, relative to that the moon it self is roughly stationary. It does move across the sky a little bit, but only a tiny fraction of how much it appears to move due to the rotation of the earth. Draw a crescent moon on a piece of paper and pretend your head is the earth, keep the paper stationary on one side of your head and move your head through 180 degrees, now imagine you are standing on your nose and notice what the moon looks like from that perspective. Vespine (talk) 23:44, 30 May 2012 (UTC)