Wikipedia:Reference desk/Archives/Science/2006 October 9

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==Edison]] 14:26, 10 October 2006 (UTC)

As long as the car is on level ground, the only work done is that to overcome the rolling friction. With a well lubricated system, that should be quite low. You could also have the car at a slight negative incline, so that the downward force due to gravity is almost equal to the friction. In this case, you could push the car with you little finger. StuRat 12:07, 22 October 2006 (UTC)

Babirusa

I was wondering if you could help me find a source for a piece of information that could go in the article; I don't know if it goes here but their doesn't seem to be a help section for Wikipedia itself. On the talk page it has a section called 'The antidote?'. I don't know a good way to sum it up, so go and read it. The point is, the piece of information removed is true; I saw it on The Life of Mammals. The animals congegrate at a natural patch of a type of clay that neutralises poison in plants they eat. Although this is a fact, my Googling skills are poor so I don't know a reputable webpage I could cite. Any help? (P.S., the section on if they're kosher or not is bizarre and I don't know if it should be in.) Vitriol 01:21, 9 October 2006 (UTC)

The BBc's own website http://www.bbc.co.uk/nature/animals/features/274feature1.shtml is much more guarded on the reasons for them eating the clay so maybe it is uncitable as a fact. Curse that evil Attenborough. MeltBanana 01:48, 9 October 2006 (UTC)

Size of Human Epidermis Cell

Around how many micrometers in length is a human epidermis cell? Thanks. --Proficient 01:33, 9 October 2006 (UTC)

Which bit? Try here. Vitriol 01:42, 9 October 2006 (UTC)

I'm not sure actually. Whichever would come off if you scraped off a sample and put it under a microscope... --Proficient 05:02, 9 October 2006 (UTC)

I have another question: What color are the organelles of cells, specifically eukaryotic cells? (I know chloroplats are green, but what about ribosomes, mitochondria, and such?) I would assume that it might depend on the specific type of cell, but I want to make sure. When looking at them in microscopes, it would also depend on the dye, I believe. Whenever I see diagrams, they tend to be different from one another. So what color are they if they were able to be seen clearly without dye? This is a weird question, but thanks if you can answer it. --Proficient 05:08, 9 October 2006 (UTC)

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bursting cells

how come an animal cell will burst if it lets to much water in but plant cell dont? —Preceding unsigned comment added by 68.19.209.91 (talk • contribs)

Cuz plant cells got cell walls of cellulose and animal cells ain't now stop asking homework questions and do your own research. It's probably in that bio book of yours. =O Hyenaste ^(tell) 02:54, 9 October 2006 (UTC)

nah.. i looked in my book for about an hour for all of these questions and never found anything. ive been looking on the net for at least 3 hours for an answer to any of these and havent found anything close to an answer. —Preceding unsigned comment added by 68.19.209.91 (talk • contribs)

Have you got the right book? Its the biology one you need! 8-)--Light current 03:10, 9 October 2006 (UTC)

yes...i hae the right book$$~& —Preceding unsigned comment added by 68.19.209.91 (talk • contribs)

Look here Plant_cell--Light current 03:19, 9 October 2006 (UTC)

If you are really having problems with your book, this website has some good narrated biology animations. Also, please sign your comments with ~~~~ Dar-Ape 03:20, 9 October 2006 (UTC)

What's in a plant cell that's not in an animal cell? --Bowlhover 05:52, 9 October 2006 (UTC)

Like Hyenaste said, cell walls of cellulose. And chloroplasts --GangofOne 09:46, 9 October 2006 (UTC)

Stop bitching at people who ask for help with homework, we dont do homework for people, we are happy to help with it though. Philc _T^E_C^I 17:43, 9 October 2006 (UTC)

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Human skin colour

Why is human skin the colour it is (ranging from a very pale pink to a dark brown shade)? I know the variations are caused by melanin levels, but I'm curious as to why we aren't blue or green or something. CameoAppearance ^orate 05:18, 9 October 2006 (UTC)

Great question. I don't know the answer, but looking at the box at the bottom of brown, I would say that human skin color is really all shades of brown (not so much pink, really). And brown is considered a "neutral" color, although I admit I don't really know what that means. Looking at nature, it seems that things that come in non-neutral colors tend to have good reason to be those colors -- leaves are green because the pigments for photosynthesis happen to absorb the other frequencies. Frogs and peacocks and butterflies come in crazy colors for defense, or sexual selection or stuff like that. But we humans, though we need some color for UV protection, it doesn't really matter what color it is. And things where color doesn't matter -- tree trunks, roots, worms, dog paws, most mushrooms -- seem to tend to be brownish. Could it have something to do with brown being (according to its article) a tertiary color in the "original sense"? It's what you get when you mix together all three primary colors, so maybe when you throw together various atoms and molecules, in the absence of evolutionary pressure on hue, you tend to get brown? --Allen 06:38, 9 October 2006 (UTC)

I don't have specific answer, but note ALL MAMMALS are in the range of browns to black, and maybe white hair, with only a few exceptions, like purple-assed baboon, and mandrill. The previous answer sounds good to me. --GangofOne 09:40, 9 October 2006 (UTC)

It seems that in mammals, skin colouring pigments such as melanin and [what was the other one, again?] evolved primarily to protect the skin from UV radiation, while for purposes of camouflage or mimicri, fur colour is varied. As fur is a common chararteristic of all (or most) mammals there was no evelotuionary pressure for varying skin colour -- it would pointless as one cannot see it underneath the fur, and so everything stayed with the UV protection compounds that worked out well. At least that's my guess. Simon A. 17:07, 9 October 2006 (UTC)

The "other one" is another form of melanin, orangy rather than brown. The two forms are pheomelanin (red to yellow) and eumelanin (dark brown to black).

Atlant 17:16, 9 October 2006 (UTC)

In order to be blue or green, wouldn't we have to have copper in our blood instead of iron? User:Zoe|(talk) 02:55, 10 October 2006 (UTC)

Yeah, I suppose. Well, my question's been answered. Thanks! CameoAppearance ^orate 16:25, 10 October 2006 (UTC)

Well, humans who don't have much (of either type) of melanin are pink as a result of our red blood, but that relatively-unsaturated color could be easily over-ridden by other pigments in the skin; note in particular the mandrill[1]. Also, pigments aren't the only way to generate color. Some of the most-brightly-colored feathers and scales are often colored as a result of diffraction patterns. So if there were some evolutionary advantage to us being, say, bright blue, that's probably what we'd be.

Atlant 17:41, 10 October 2006 (UTC)

Interesting. --Proficient 06:39, 18 October 2006 (UTC)

international awards in physics.

Nobel prize has been critized(particularly in science)for awarding people after their career has almost ended(as if a lifetime acheivement award) rather than award "to encourage young minds". IS THERE ANY UPCOMING AWARD CEREMONY THAT ASSURES PRIZE TO YOUNG MINDS(IN PHYSICS)?____202.71.153.76 05:22, 9 October 2006 (UTC)ANURAG

Please don't shout. DirkvdM 09:23, 9 October 2006 (UTC)

see List of prizes, medals, and awards --GangofOne 09:31, 9 October 2006 (UTC)

Did you try Ig Nobel Prize ? -- DLL ^{.. T} 17:03, 9 October 2006 (UTC)

The IISEF is one of the highest honors. — X [Mac Davis] (SUPERDESK|Help me improve)02:41, 11 October 2006 (UTC)

The LeRoy Apker award is one. There are many. sthomson 17:29, 20 October 2006 (UTC)

prices of toluene

when looking up the prices of toluene in chemical market reporter, I see "Toluene, spot" and then a per pound price. What does the "spot" mean?

Probably Spot price. Clarityfiend 05:42, 9 October 2006 (UTC)

Oil absorption into skin

When you rub oil into your skin (such as for massage or to moisturize dry skin) it seems to be absorbed. This is probably a dumb question, but can the oil go into the bloodstream and eventually become part of your body fat? Or if not, what happens to it? The more I think about it, the more I doubt it would work that way, but I don't know why. --Grace 05:46, 9 October 2006 (UTC)

A lot of the ingredients listed in moisturiser will be broken down and either excreted by the body (eg methylparaben), or used in metabolism (things like glycerol and stearic acid). it is possible for compounds to be stored in the fat layers of your body, but they are usually slowly broken down and excreted. Xcomradex 06:15, 9 October 2006 (UTC)

I'm talking about actual oil, though, like olive oil, which is sometimes used for massage. Surely you aren't saying that people watching their weight should avoid even external contact with fat? :) --Grace 09:20, 9 October 2006 (UTC)

The major component in olive oil, oleic acid, does travel through the skin. so at least in theory some of it wil contribute to yur overall energy uptake. however this is dependant on how much of it makes it past the outer dead layers of skin (which won't metabolise it) into the bloodstream. i'd say thats probably not a lot. Xcomradex 09:51, 9 October 2006 (UTC)

chemical engg

oxygen demand for prod of recombinant protein

production of recombinant protein by a genetically engineered strain of e.coli is proportional to cell growth .ammmonia is used as nitrogen source for aerobic respiration of glucose.the recombinant protein has an overall fortmula C H 1.55 O 0.31 N 0.25. THE YIELD OF BIOMASS FROM GLUCOSE IS MEASURED AT 0.48g/g.the yield of recombination of protein from glucose is about 20% (percent) that for cells..

1.how much ammmonia is required?

2.what is the oxygen demand?

3.if the biomass yield remains at 0.48g/g ,how much different are the ammonia and oxygen requirements for wild type e.coli unable to synthesize recombinant protein.......

Please read the text at the top of this page. Do your own homework. Simon A. 12:03, 9 October 2006 (UTC)

Please tell us what you understand in the text and what needs a particular help from us. -- DLL ^{.. T} 17:01, 9 October 2006 (UTC)

Skies of the distant past/future

Let's say that I want to know what the skies looked like 50 million years ago. Is there a star chart program that I can use for this? Of course it will need to take into account proper motion, because the stars move a lot over millions of years. --Bowlhover 06:29, 9 October 2006 (UTC)

There's a number of free astronomy programs that do this kind of stuff; I use Celestia although there are certainly other (and maybe better) programs. Keep in mind, though, that errors accumulate over time; it's possible to get an idea of how the sky looked like to ancient Romans (being only about 2000 years in the past), but I would not really trust any such program to show anything meaningful for a date several million years in the past. Ferkelparade π 06:35, 9 October 2006 (UTC)

effect of growth on oxygen demand

the chemical reaction for conversion of ethanol to acetic acid (C2H4O2) is

C2H6O + O2------> C2H4O2+H20

Acetic acid produced during growth of Acetobactor aceti, which has the composition C H 1.8 O 0.5 N 0.2; biomass yields from substrate is 0.14g/g. Product yield from substrate is 0.92g/g. Ammonia is used as nitrogen source. How does growth in this culture affect oxygen demand for acetic acid production???

I DON'T MEAN TO BE RUDE, BUT DON'T WRITE IN CAPITALS, PLEASE. Aaadddaaammm 08:41, 9 October 2006 (UTC)

Thanks for removing the caps, but please also sign your comments by adding four tildes. And do your own homework. Simon A. 12:02, 9 October 2006 (UTC)

It's perfectly fine to ask for homework help here. It is not, however, perfectly fine to dismiss a question with the rude "do your own homework". That sort of rudeness at the reference desk really should stop. If someone's sole contribution to an answer is "do your own homework", I would suggest either [1] silence, or [2] substituting "If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers."- Nunh-huh 12:10, 9 October 2006 (UTC)

I agree. Since this is the Science desk, we should have a proper calibrated "Scale of Rudeness", going from 1 to 5, with standardized rudeness templates. 'Very Rude' (5) will be reserved for those who copy their homework assignment directly, and don't sign. 'Slightly Rude' (1) is for those who don't use the search box first. --Zeizmic 13:18, 9 October 2006 (UTC)

i need help

hi im a student doing a national diplomea of allpied sciences and i have been looking for an atricle everywhere and just can find it its called 'a mind to crime' by Anne Moir and David Jessel. i would greatly apprectiate it if you could provide any revelant info.

thank you very much -demoness_althea66611:33, 9 October 2006 (UTC)

Anybody ever told you about Google Scholar. I just typed in "a mind to crime Anne Moir David Jessel", and it immediatly told me that this is not an article, but a book (Signet, 1995). See here: ISBN 071813768X Simon A. 11:54, 9 October 2006 (UTC)

http://www.amazon.com/Mind-Crime-Moir/dp/0451196295/sr=8-1/qid=1160394637/ref=pd_bbs_1/104-8179265-6067933?ie=UTF8&s=books. ISBN 0451196295. Click on the ISBN link to look for sources. Presumably you can ask your local library to obtain it through interlibrary loan. - Nunh-huh 11:52, 9 October 2006 (UTC)

Underground nuclear tests

From what I've read about today's test by North Korea, it was tested underground. So, basically, I'm wondering how they do this underground. Do they have a really big cave that it's done in or what? Do we have an article on it that I didn't see linked at the nuclear testing article? Dismas|^(talk) 12:49, 9 October 2006 (UTC)

They said it was in a mine (now abandoned). The difficult thing would be to seal it before the explosion, so it doesn't leak. --Zeizmic 13:13, 9 October 2006 (UTC)

Of course now it's abondoned. But Kim Jong Il stuffed babies in around the bomb to see the effects. — X [Mac Davis] (SUPERDESK|Help me improve)

That's not so hard, just use a manhole cover... but don't aim it at the ISS! --Jmeden2000 14:37, 9 October 2006 (UTC)

[after edit conflict]I think in general they just drill a hole, lower it in, and plug the hole, but they could also use old mineshafts. I think most caves might not be in a suitable type of rock. Wikipedia could do with more information if anyone has it.--Shantavira 13:15, 9 October 2006 (UTC)

It can vary a lot depending on the purpose for the test. But usually you dig a big hole, drop a bomb into it, and cover the hole. You can use old mines or whatever as well. The most important factors are the type of rock you are detonating it in and taking care that even if the bomb goes over the maximum predicted yield it won't vent. Other issues are whether or not the seismic activity will affect nearby people and wildlife but usually that sort of thing is set to the wayside, especially with small bombs. I imagine they also take into account whether or not there is water running through the area (the rock inside the test area will become quite hot and radioactive). One could create an article on it though personally I find the subject pretty boring — the technical issues are predictable and fairly banal. --Fastfission 14:59, 9 October 2006 (UTC)

Decoupling may also be a factor. You don't necessarily want all the evolved energy going into seismic activity lest everyone else know exactly how big a bang you produced, so you may excavate a larger cavity than you would need merely to hold the nuke's phsyical volume.

Atlant 17:20, 9 October 2006 (UTC)

News reports in Korea have said that a horizontal mineshaft is thought to have been used instead of a vertical one. --Kjoonlee 18:50, 9 October 2006 (UTC)

It was done under a 360-metre high hill/mountain. --Kjoonlee 18:53, 9 October 2006 (UTC)

Thanks for the responses, everyone! Although, in the case of N. Korea, I would think that they would want as much of the energy as possible to go into seismic activity. It makes for better advertising for themselves if they intend to sell the technology to someone else. Thanks again, Dismas|^(talk) 21:48, 9 October 2006 (UTC)

I agree. Most of the effect they'll get out of a nuke is rhetorical or political; there is little reason for them to want to make their tests look smaller than they are. --Fastfission 00:44, 10 October 2006 (UTC)

That brings into play a new skill: making the bomb appear bigger seismically than it actually is. Everything I've read in the past few years was about tricks to obscure the test. The near-surface location is good, packing with tons of old munitions would add to the effect. It's not hard to get an M4 explosion. Wouldn't it be funny if it wasn't nuclear at all? --Zeizmic 17:14, 10 October 2006 (UTC)

That's why the Americans (and, I think, the Russians) have various detectors to detect leaks of radioactive materials which would have been given off by the blast. [2]. If the Americans still had their Velas, they could have found the site and nature of the blast precisely (the ones which found the Gamma ray bursts which America mistook for Soviet nuke tests on the dark side of the moon) by detecting the gamma rays and EM pulse from the blast. Laïka 17:15, 11 October 2006 (UTC)

Which is why all the news reports are still saying things like unconfirmed or alleged about the test. --WhiteDragon 16:56, 16 October 2006 (UTC)

Reduced salt area

Sometimes while going on a highway we see a sign saying "Reduced Salt Area". What does this mean?

In Korea, only old people drive on highways with reduced salt... --Jmeden2000 14:08, 9 October 2006 (UTC)

Maybe one of the scientists assigned to the project has access to Wiki...

In seriousness, a quick google returns that a 'reduced salt area' is one where salt used to deice roadways is reduced or eliminated due to conservation concerns. --Jmeden2000 14:32, 9 October 2006 (UTC)

Not just conservation concerns. Watershed areas are often marked this way to limit the amount of sodium that ends up in the human drinking water supplies.

Atlant 17:23, 9 October 2006 (UTC)

That may be true for some areas, but most road salt used in the US is actually calcium chloride, since its more effective than sodium chloride and much less harmful to the local ecology (but still not 100% safe). --Jmeden2000 18:48, 9 October 2006 (UTC)

Here in my part of New England, it's definitely good-ole sodium chloride, probably because it's cheaper. The usual "winter mix" is sand and NaCl. On the other hand, I use CaCl₂ when I spread "salt" at all, primarily because I care about my plants and my concrete.

Atlant 00:39, 10 October 2006 (UTC)

its CaCl₂ of course, which is why it is more effective mole for mole than NaCl. Xcomradex 01:40, 10 October 2006 (UTC)

Correction accepted -- thanks!

Atlant 17:44, 10 October 2006 (UTC)

Gotta be careful with practical measurement of "effectiveness" though: to get a mole of ions from NaCl, you'll need 29 g of it, whereas you'll need 37 g if you use CaCl₂. DMacks 17:58, 10 October 2006 (UTC)

true, but there are other reasons to be careful with "real-world" measurements too. dissolving NaCl in water gives neglible temperature change, however dissolving anhydrous CaCl₂ in water gives a whopping exothermic reaction (release of heat) as the Ca(H₂O)_n²⁺ ions form. so in a simply weight for weight measure, i'd say calcium chloride still wins. Xcomradex 01:28, 11 October 2006 (UTC)

Refraction of light

[copied from talk page ]
Is the light sensible to changes of pressure? For example, the sound pressure, will affect in any way the direction of the light, even could be very little influence? —The preceding unsigned comment was added by 80.103.32.2 (talk • contribs) 30 September 2006.
[end copied]

According to List of indices of refraction, the answer is yes. --Allen 16:14, 9 October 2006 (UTC)

I agree. However, in most cases, the change due to temperature is larger, see e.g. twinkling. But I remember that in undergrad lab practice, we did an experiment, where one arm of a Fabry-Perot interfreometer is led though a glass cylinder. When the cylinder is being evacuated one can see the fringes move. A pretty complicated and imprecise way of building a barometer. Simon A. 17:16, 9 October 2006 (UTC)

narcotics

(1)is alcohol a narcotic. (2)is nicotine a narcotic. (3)is caffine a narcotic. i have spent 2 hours on the internet trying to figure this out and i cant. thank you kevin

No, no, and no. Narcotics are, by scientific definition, derived from opium. None of those are. Even under the slightly-looser US legal defition (which includes coca-derived drugs) they aren't included. -- Plutor ^talk 11:14, 10 October 2006 (UTC)

To be nitpicky, narcotics are not derived from opium, but work by binding to the opiate receptor. alteripse 23:05, 9 October 2006 (UTC)

I believe that that is actually the definition of opioids. From a cursory search and a quick read of our articles, it appears that narcotics are a subset of opioids. -- Plutor ^talk 11:14, 10 October 2006 (UTC)

In the early 20th century all known narcotics were derived from opium, but that definition is long obsolete. My point was that synthetic opioids are considered narcotics by doctors, pharmacologists, and US law enforcement people but many are not derived from opium in any direct way, but simply share the ability to bind and activate opioid receptors. The word narcotic is somewhat slippery. In a medical context opioids and narcotics are typically considered interchangeable terms. In a US law enforcement context, the term narcotic is sometimes used more widely for all controlled substances, a usage that makes doctors cringe. alteripse 15:27, 10 October 2006 (UTC)

They're all psychoactive drugs, though. From the article: "In the West, the most common by numbers of users are caffeine, alcohol, and nicotine, in that order." DirkvdM 08:22, 10 October 2006 (UTC)

Wood Integrity

What is the integrity of pine wood? I would like to know the exact formulas so that I can use them for a medival seige engine.-- Meteshjj _{We come from the land} ^{of the ice and snow} 20:55, 9 October 2006 (UTC)

I did a google search on "pine wood strength", and looked at our article wood, and it looks like the answer to your question might depend on too many things for an easy answer: species, growing conditions, treatments, and drying temperature may all need to be known to figure out exact strength. You might be better off directly experimenting with samples of the wood you have to figure out its particular strength. And do be careful with any war machines you build. You might want to check with local authorities for permission beforehand. --Allen 23:13, 9 October 2006 (UTC)

I know that there is a specific formula including the aforementioned variables. i counted on testing for the various variabls before I walked into a crapload of math. By the way, It is legal to build a trebuchet in my area, as we often host thePunkin Chunkin Contest.

Older engineering handbooks, from say before 1960, frequently contain this kind of information, and they can also be found very inexpensively in used book shops. For example, Eshbach's Handbook of Engineering Fundamentals, 2 ed. (1936) gives the modulus of elasticity of northern white pine as 1,280,000 lbs. per sq. in., as well as data on other parameters and species. I have no idea if these numbers, probably measured on old growth timber, will hold up for stuff you can buy today. -- The Photon 01:58, 11 October 2006 (UTC)

Thank. I will try to find the before sited books.-- Meteshjj _{We come from the land} ^{of the ice and snow} 05:47, 11 October 2006 (UTC)

Is it possible to artificially increase a metal's physical weight to indefinitive amounts?

Monday, 10-9-06; Portland, OR; 1:38pm West Coast Pacific Time;

Original post: http://wiki.riteme.site/wiki/Talk:Heavy_metals#I.27m_searching_for_information_on_how_to_artificially_increase_a_metal.27s_physical_weight_to_indefinitive_amounts.

Is there an authority who can provide an answer on how to artificially increase the physical weight of a small piece of metal (say the size of a 1/2 inch diameter galvanized steel washer)? Is this only theory, or has this concept actually been proven? Bear in mind, that I wish to affect only the weight (or density) of this size and not the physical dimensions of this size; in other words, is it possible to artificially increase the weight of this size to an indefinitive weight such as, for example, 50 lbs., 100 lbs., 150lbs., 200lbs., 500lbs., or even to a weight of 1,000 lbs.? Why would I want to try this? For a private science project I'm cogitating. --MyPresentCPUisTooSlow 21:08, 9 October 2006 (UTC) MyPresentCPUisTooSlow

Since metals cannot generally be compressed much, I think the answer is a firm NO!--Light current 21:19, 9 October 2006 (UTC)

You could make it out of Osmium or Iridium - the densest relatively common materials that we have available on Earth - a sphere with a radius of about 22 cm (~9 inches) of either metal has a mass of about 1 tonne. Into the realms of sci-fi - and if you could make it out of the same stuff and density that white dwarf stars are made from - then a sphere only 5 mm (~0.2 inches) in radius has a mass of about 1 tonne. Better still, get a lump of neutron star with the same density as a neutron star in the upper mass range - a sphere 5mm/0.2 inches in radius can have a mass approaching half a billion tonnes - and would have a significant gravitational effect if you got close to it!Richard B 21:49, 9 October 2006 (UTC)

Accelerate it to relativistic velocity; as it approaches the speed of light, it will gain mass. TenOfAllTrades(talk) 02:20, 10 October 2006 (UTC)

While the mass of the piece of metal is an inherent property of matter, and can only be altered by relativistic effects as it is accelerated to near the speed of light, the weight is technically an effect of the gravitational attraction. Just as you can make a metal washer weightless by putting it in orbit or dropping it, you can make it weigh more simply by taking it and the spring scale you are weighing it with to a planet where the gravity is greater. If you want a 1 ounce (say) washer to weigh 1000 pounds, which is 16,000 times as much, all you have to do is weigh at some place in the universe where the gravity is 16000 times as much as on earth. On the surface of a neutron star the gravity is at least 2×10¹¹ that on Earth, so the washer which weighs 1 ounce on earth would weigh at least 12,500,000,000 pounds.Edison 14:37, 10 October 2006 (UTC)

As long as you are talking about pounds-force, of course. You should identify them as such when you use them here, because they aren't the pounds a hardware store uses when it sells washers by weight. Gene Nygaard 18:36, 17 October 2006 (UTC)

Water...Sily question?

oxygen is h20, so if I took 2 parts hydrogen to 1 part oxygen could they be 'mixed' together to form water? Or does it take some form of binding much more complex than simply 'pouring' the two items together?? I know this is probably silly and that it takes much more than this, but I figure this is the perfect place to ask such a question! ny156uk 22:00, 9 October 2006 (UTC)

I assume you that water is H2O. All it takes is a little heat (or a spark). Hydrogen and oxygen will react explosively to form water. Not recommended for casual users. Dragons flight 22:04, 9 October 2006 (UTC)

You can also have a controlled burning of Hydrogen - say from a tap connected to a gas cyclinder to form steam - if you put a cold object above the flame, water will form from the steam produced. The reaction doesn't have to be explosive.Richard B 22:46, 9 October 2006 (UTC)

(edit con) You have to ignite the hydrogen, but also if they are in liquid, volume(ml) * concentration(m/dm³) = moles(m) and you need correct amount of moles not equal volume. You will need twice as many moles of hydrogen as oxygen (since they are both diatomic the ratios will be the same as in the molecular formula), but generally people would use one in excess to ensure the other is completely reacted, most likely oxygen in this case. Philc _T^E_C^I 22:06, 9 October 2006 (UTC)

but if you do the reaction in the gas phase, then you can simply mix one volume of oxygen to two volumes of hydrogen then ignite, since to the first approximation the molar volume of all gases is 22.4 L/mol. the above caveat on this reactions explosive nature does apply of course. Xcomradex 01:38, 10 October 2006 (UTC)

I believe the splendidly-named Gay-Lussac had something to say about this. --G N Frykman 07:00, 10 October 2006 (UTC)

We even have an article on oxyhydrogen flame. To add a few more things: As alrady poined out: if you mix hydrogen and oxygen you get highly explosive stuff which in German has the nice name Knallgas ("boom gas"). After you ignite it (from save distance) you get a load, sharp boom noise and water, in gaseous form, of course, because an explosio is hot. In class demonstration, one hence does it in a closed glass container such that one can wait for the water gas to cool down and condense. One might be disappointed to see that a litre of Knallgas condenses to less than a millilitre of liquid water. And in case you don't like explosions, a fuel cell is your device of choice. Simon A. 07:35, 10 October 2006 (UTC)

There are no silly questions, just silly moments to ask them. You actually stumbled on something big. See Hydrogen economy. DirkvdM 08:28, 10 October 2006 (UTC)

However, there may be such things as silly answers (not that the above is silly). 8-)--Light current 08:45, 10 October 2006 (UTC)

At the Exploratorium I saw a nice exhibit in which water was broken up by electricity to hydrogen and oxygen, The hydrogen and oxygen were then allowed to exit small glass tips near one another and burned. As I recall, the burning produced water. It was not perpetual motion, since the electricity input to break down the water was greater than the energy obtained by burning it. Edison 15:03, 10 October 2006 (UTC)

Youre talking complete hydrolysis 8-)--Light current 23:47, 10 October 2006 (UTC)

If we include the energy converted to sound and light, then the energy needed to split the hydrogen from oxygen should exactly match that created by burning them together. However, since you will never have a 100% efficient mechanism, there will be energy lost in the process, making a perpetual cycle impossible without the addition of outside energy. StuRat 00:52, 11 October 2006 (UTC)

Mother gull is double-clutching this year...

It's now October and it's starting to get cold, yet the GGB gull hen that nests on the roof opposite me (and has done for ten years or so) appears to be sitting on another clutch of eggs (her first brood fledged about six weeks ago). Any bird experts here? Do you think the chicks have any chance of making it through the winter? I'll do my best to make sure that the hen bird gets plenty of food... --Kurt Shaped Box 22:07, 9 October 2006 (UTC)

Perhaps the gull laid more eggs anticipating your urge to help her? --Russoc4 23:37, 9 October 2006 (UTC)

I was thinking that myself. Ever since I saw she had a nest, I've been lobbing food out of my window onto the roof for her. I guess I've made a commitment now... :) --Kurt Shaped Box 23:39, 9 October 2006 (UTC)

Yes, you've likely changed the whole local ecological balance. StuRat 00:42, 11 October 2006 (UTC)