Wikipedia:Reference desk archive/Science/2006 September 19

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September 19[edit]

Work, lifting vs walking - 7th Grade Physics[edit]

Yes, this is a homework problem for the kiddo; however, I am not understanding the concept trying to be taught here, so thought I'd see if someone can lead me in the right direction (38 Yr old CompSci Major slinks off to the corner and cries....) The problem is this - A woman lifts her 100-netwon child up 1 meter and carries her a distance of 50 meters to the crib. How much work does the woman do?

Because of Work = Force x Distance, I can see that the woman lifting her child exerts 100 joules by lifting the child 1 meter. How do we account for the 50 meters that she walks? Surely she is doing some work? But would the work exerted simply be 100 newtons times the 50 meter walk? 1001001 00:56, 19 September 2006 (UTC)

No! She is doing no work in carrying the child (assuming she is not bobbing up and down as she walks-- we will assume this) 8-)--Light current 01:49, 19 September 2006 (UTC)
While the horizontal movement requires energy, it is not work in the physics sense, except for the acceleration and deceleration of the combined mass of woman and child, which are probably only over short distances. If there are no figures for the mass of the woman, or the accelerations, (and it 7th grade) it's probably meant to be assumed negligible. (Probably bonus points for identifying the assumption.) Peter Grey 01:56, 19 September 2006 (UTC)
Peter, I basically agree with you, but I would say that most of the work she does is due to microscopic accelerations and frictions in her muscle cells, and that this does count as physics work (in real life, not for the kid's class). I would also argue that the work she does carrying the child probably far outweighs the work she does lifting the child. Almost certainly, though, the teacher wants the student to pretend no work is being done in the carrying. (Not that going for the extra credit isn't a good idea.) --Allen 02:25, 19 September 2006 (UTC)

TMI--Light current 02:33, 19 September 2006 (UTC)

I pretty sure that the question is asking how much work is being done only against gravity, and only whatever affects the baby - which I personally think should be stated very clearly in the question. Of course, some energy is expended in the part of the force that's counteracting friction in the vertical and horizontal directions, as well as all those biological processes mentioned before, plus the work necessary to lift the weight of her arms and etc. This was one of the toughest things for me to understand myself in middle school, because you have to understand that all of that "off-to-the-side" work is being ignored. All that they care about is the work against gravity. As another example, holding a pen up needs impulse and energy is being used in your hands/arms to create the impulse, but none of that energy is actually going into the pen (neither potential nor kinetic), so it doesn't count as work. Also note that heat transfer is being ignored too (though it'll eventually start playing a role in a future course, once you get into heat engines and gas laws and such). —AySz88\^-^ 04:25, 19 September 2006 (UTC)
Well put, AySz88. In my opinion, trying to teach kids, without explanation, that they're not doing any work as they carry things around, even though they intuitively know they are, is an unhelpful oversimplification. Light current, that's why I don't think it really is TMI. It's just enough "I" that kids can understand what the lesson is driving at without being sidetracked by apparent absurdities that aren't really there. --Allen 04:51, 19 September 2006 (UTC)

Just wanted to add my thanks to this - I really didn't understand what the question was going for, but it makes sense now. I think that I can even explain it to the kiddo now. (and they say raising kids doesn't generate work, HA!) 1001001 05:08, 19 September 2006 (UTC)

Isn't this a nice (and educative) example of how physics is a model of reality and not reality itself? An much used modelling 'error' is to assume no friction. Let's say the baby is lifted onto a table on wheels. Assume no friction in those wheels. It takes energy to get the table going, but stopping it 'releases' that energy again. In a modelled world, that is. I'm no physicist, so I'm not sure if that example was a good one, but the first sentence touches on the core of the problem, right? DirkvdM 07:08, 19 September 2006 (UTC)
Hmmm, one thing still bugs me about my example. If there were any energy lost by friction, that would go into heat, but what about the 'releasing' of energy by stopping. Where does that 'come from'? I assume this depends on which system you look at and whether it is open (to what?) or not, but I can't wrap my head around it. (Suppose my head isn't big enough. :) ) DirkvdM 07:12, 19 September 2006 (UTC)
THe energy of motion is of course 1/2 mv^2 and when you stop the trolley the energy goes into stretching your arms or dragging you across the floor creating heat by friction. And no, I woulddnt agrre with your last statement. 8-)--Light current 07:41, 19 September 2006 (UTC)
Yeah, I understand that. That's the reality bit. But I meant that in the model, if you pick up the baby and then put it back down, you end up with the old situation. But if you move the table and stop it, something has changed, namely the location of the table. Also, you excert energy twice. Maybe I should be thinking about energy as a vector. The model sort of assumes that the energy is 'won back' because it worked in opposing directions. (And in reality that would (to some extent) be possible if you slowed down with a dynamo.) So the two situations are 'energetically equal' (or how should I put that), despite the fact that a change has occured. This makes me think of something different, which I will ask a separate question about below (space travel). DirkvdM 08:45, 19 September 2006 (UTC)
Wouldn't the work be zero, according to the old saying "A woman's work is never done?"Edison 14:42, 19 September 2006 (UTC)
You should certainly not think of energy as a vector. If you're thinking that energy has a direction, you're probably thinking about momentum instead (which does). If I may quote myself here, I discussed some of the physiological aspects of this situation about two months ago. In this case, the important thing to say is that the woman does so much work on the child. She may do plenty more work on her own tissues, the floor, the air, etc., but that's not the (implied) question. --Tardis 16:41, 19 September 2006 (UTC)

Tylenol Overdose[edit]

A health question: I was recently told that taking more than the extra dose as said on the bottle of tylenol is a serious health risk; I have been feeling bad lately so I have been taking 4 Tylenol extra strength 500 mg tablets twice daily, double the twice daily two tablet this a health hazard? Thanks! ChowderInopa 03:03, 19 September 2006 (UTC)

Yes, taking more than the recommended dose is a health hazard, so is not going to the doctor when 1g of acetominophen/day is not enough to alleviate your pain. You should schedule a visit with a physician. In case you are curious, acetominiphen overdose has a slow onset and can lead to a very slow, very painful, very irreversible failure of the liver.Tuckerekcut 01:26, 19 September 2006 (UTC)

Thanks, this is only for today though...As in, for months I have not had any medicine, now when im feeling sick I took double starting this morning, then a friend said that was crazy and I should throw it up...but then i responded that it was just 8 pills in one day. All I am asking is, a one or two time double dosage during one day isnt a serious problem is it? By the way I am a 200 pound male, so the effects should be dampened. I mean it sounds like you are saying continual abuse hurts the liver, which i of course agree with, but just doing so today isnt horrible correct? This is not merely a context specific question, I am curious for general double doses with any medicine. Thanks! ChowderInopa 03:03, 19 September 2006 (UTC)

In your case, I would not recommend taking a double dose again, in some people without other obvious pathologies, taking the dose that you took even one time could cause clinically relevent, albeit minor and ephemeral, symptoms, especially if compounded by alcohol (be it in your beer or your cough syrup). The general case is even more fuzzy. For instance lithium can cause severe life threatening complications in certain circumstances if a patient takes a double dose. Other medicines have an even smaller theraputic ratio, (adriamycin/doxyrubicin comes to mind, but these things are not likely to be self-administered). In general, monoamine oxidase inhibitors and drugs for bipolar disease have some of the narrowest theraputic ratios, I believe. This information is all trivial, though. If you feel that you have a medical problem, see a doctor. She will be in a much better position to tell you what is healthy for you specifically. Also, please sign your edits with four tildes in the future. Tuckerekcut 02:12, 19 September 2006 (UTC)

No, I feel great and feel no problems whatsoever, I was just curious to make sure I hadnt done something completely stupid, like knock myself into a coma. How many would that generally take? 10 pills? 20? In the movies you always see a bottle full, but that seems to be way too much compared to what you are saying could hurt me... ChowderInopa 03:03, 19 September 2006 (UTC)

I have heard of people dying from as little as 8, which is only double what you're taking. You're at a much higher risk of harming yourself if you are in a weakened state (i.e. if you are sick) because your body is weak and may react strongly to the drugs that you (over) induce. Tylenol are generally pretty safe, which is why they're so easy to put on the market, but there is a reason that the warnings are there in the first place so there's no reason to deliberately put yourself in danger. I'm the kind of person that refuses to take any medicine, especially pain killers, unless it is really needed to help increase the speed of recovery. I can handle a little bit of pain and discomfort, and when it get's bad enough that I can't, I know that it's time to get some kind of treatment.  freshofftheufoΓΛĿЌ  03:27, 19 September 2006 (UTC)
I don't know if you've actually received a medical opinion or not yet. In Australia, acetaminophen is known as paracetamol, and the typical healthy adult dose is 1 or 2 500mg tablets 4 times daily, with a maximum dose of 8 tablet (or 4g) daily. If you have other health problems the safe dose for you may be less than this. Read the packet instructions on your tylenol. It will probably say something like this. If you exceed the dose, it means at least 2 things: 1.) it is not treating the illness you are using it for; and 2.) you risk toxicity, including irreversible liver damage. Either way - the most sensible course of action is to see your doctor. Best wishes, Mattopaedia 04:10, 19 September 2006 (UTC)
we do have an article on acetaminophen, you know... but the posters are right. Overdosing on paracetamol can nuke your liver, leading to a nasty death. --Robert Merkel 05:00, 19 September 2006 (UTC)

MPTP article image[edit]

Is the image in our MPTP article correct? If not, what needs to be done to fix it? On the talk page, a visitor has called the image's accuracy into question, but no one watching the article is qualified enough to fix a chemistry diagram. Thanks for any help you can give! Foobaz·o< 02:00, 19 September 2006 (UTC)

According to chemfinder, ChEBI, and University of Akron's Chemical Database both the formula and the structure (diagram) are correct.---Sluzzelin 05:45, 19 September 2006 (UTC)

the diagram is correct, it is just that the name is misleading. Xcomradex 10:54, 19 September 2006 (UTC)

Freezing to death[edit]

Would a warm or cold blooded animal (assuming that they are the same size, like a large toad and a rat) freeze first?--Peta 04:32, 19 September 2006 (UTC)

I figure the toad would freeze first, because it isn't producing as much heat of its own, and is probably starting from a lower temperature to begin with. But it might not freeze to death first, because some toads have weird abilities to live through freezings. --Allen 04:58, 19 September 2006 (UTC)
It depends, in part, whether the Ectotherm/poikilotherm was warmer or colder than the homeotherm at the time of the competition. The terms warm- or cold-blooded refer to the mechanism of thermoregulation, not the actual temperature of the organism itself. (that said, its likely the toad would freeze first, unless it was particularly toasty to begin with). Rockpocket 05:06, 19 September 2006 (UTC)
Are roast duck susceptable to the Mpemba effect? — [Mac Davis](talk) (SUPERDESK|Help me improve)05:35, 19 September 2006 (UTC)
As Allen said, there are some cold blooded animals which can freeze, and still live (I know of snakes and frogs). So the question as to which would die first, it is dependent upon the species. It would be interesting (though horrible and cruel) to see which would die first between the Wood Frog and the Arctic Fox. --liquidGhoul 05:47, 19 September 2006 (UTC)
Warm blooded animals have a constant temperature. Cold blooded ones don't. So the toad's temperature seems to be one piece of information that's missing. But even if they started off at the same temperature the rat would use its metabolism to keep it warm, so the toad would freeze faster. All this assuming were talking about live animals here and I don't know how much heat a toad can store. It would have to be one hot toad to compensate for the rat's metabolism. That said, I wonder what happens to coldblooded animals under freezing conditions. Do they all manage to survive freezing? Or do they dig themselves in at a warmer spot or something? DirkvdM 07:24, 19 September 2006 (UTC)
I can't speak for all, but it is certainly true for frogs. During winter, the tree frogs in my area will bury themselves under leaf litter, compost to keep warm. A lot of the ground dwelling frogs bury themselves underground, and some can just take it (Common Eastern Froglet seems to be able to live in absolutely freezing conditions). Mind you, this isn't Canada, the coldest it gets is -7 celcius. --liquidGhoul 08:47, 19 September 2006 (UTC)
Some cold blooded animals use antifreeze to keep from freezing, some find warm spots to survive, others die, but leave eggs that can survive freezing temps. However, the evidence that warm-blooded animals can handle cold better is in the relative scarcity of cold blooded animals in arctic environments. The problem with cold-blooded animals is that, while they may survive freezing temps, they can't do anything at those temps, like eat, breed, migrate, etc., which is a problem in places where temps are almost always below freezing. StuRat 12:38, 19 September 2006 (UTC)

Space travel[edit]

In the 'walk, lifiting vs walking' questions a few posts back it is claimed that it requires no more energy to move a baby than the energy needed to pick it up. In reality energy is expended because of friction. But take space travel, where the friction is negligible. Would it be possible to make a spacecraft that consumes no energy because it can regain the stopping energy when it reaches its destination? Of course, energy has to be put into the sytem for the first acceleration, but if the spacecraft shuttles back and forth it can use it's stopping energy to start again in the opposite direction and thus consume no more energy than for the first flight. This sounds wrong, but I can't find the flaw. DirkvdM 08:54, 19 September 2006 (UTC)

Is it possible? No. Hmm… *thinks again* Well, yes, actually. If the spacecraft could use its kinetic energy to "charge its batteries", or something, when it slows down at the destination, it could use that energy for going back. This is what electric automobiles usually do when you brake – instead of using the brakes, they start to charge the batteries with the movement of the wheels (which also slows the vehicle down). —Bromskloss 10:19, 19 September 2006 (UTC)
No, it's not possible, for two main reasons: The first is theoretical, no energy conversion is 100% efficient (second law of thermodynamics). Your theoretical spaceship would have to perform several energy conversions to 're-use' its deceleration energy, so something will always be lost in the process. The second is practical - I know of no technology which allows you to 'recover' some of the energy used for deceleration in space. Remember that, in space, there is no difference between decelerating and accelerating, both use energy. You need a certain amount of energy to accelerate to your 'cruise speed', and the same amount again to decelerate. And even if you did come up with a technology which would allow you to 'recover' some of your energy (perhaps some kind of drag against the magnetic field of a star which would induce a current in a wire?), the second law will still get you in the end.
Also, to be pedantic, there is some (very very small) amount of friction in space. Space contains particles, and these hitting your ship will slow you down. However, there are very few particles in interstellar space (tens of atoms per cubic meter, if I remember the figures correctly off the top of my head), so the friction they exert is nearly negligible. — QuantumEleven 11:40, 19 September 2006 (UTC)
Oh, come on. Of course the energy conversion isn't perfect, we all know that. I don't think the questioner was thinking of actually go out and build the spaceship! As for deceleration is acceleration, that is very true, but this time we might have a planet to crash into – freeing a lot of energy. You might wan't to "crash" smoothly, of course, but if done well (again, perfect conversion) you would still get the same energy. —Bromskloss 12:49, 19 September 2006 (UTC)
Yes, but that's exactly the problem - crashing on a planet will stop you, obviously, but I know of no way how this energy can be 'recovered', it's wasted as heat and terrain deformation. The energy is there, but it's not in a useable form (unless you want to use the heat of re-entry to boil water to turn it to steam to turn a turbine to produce electricity... but then you have to carry all this extra equipment around, so your ship is heavier, which needs a bigger heatshield... you can see where this is going, it's just not practical). — QuantumEleven 15:09, 19 September 2006 (UTC)
OK, you're clearly on a more practical level in this discussion than I am. Boiling water with the heat would have been perfectly satisfying for me. One could also imagine landing on a very high (many kilometers) platform that is not firm (as to avoid a crash), but gives way with only a little resisting force and takes care of the energy the spacecraft gives to it by pushing it down. —Bromskloss 21:32, 19 September 2006 (UTC)
This reminds me of a quite funny thought experiment: suppose you were to bore a tunnel straight through the earth that came out at exactly the other side of the globe (assuming this would be possible, of course). You could then jump into the tunnel and be accelerated until you passed the center of the earth, from which point on you would be decelerated by exactly the same amount. At the other end of the tunnel, you would stop and could just step out into the open. -- Ferkelparade π 11:50, 19 September 2006 (UTC)

Actually, it is possible, and it's being done for ages now. The moon's been going to and fro from Earth's sunside to the other side without ever having needed to charge it's batteries. It is, maybe, not a very practical way of making space ships fly, but it is certainly very economic. David Da Vit 12:12, 19 September 2006 (UTC)

Note that spaceships do reuse the energy going one way and use it for the return trip, by using the destination star's, planet's, or moon's gravity to turn the ship around (possibly after many orbits). Also, the ship may even gain velocity by using the slingshot effect. They don't come to a "stop", of course, in either case, but can get close enough to make good observations and maybe drop a probe, then return back home. StuRat 12:15, 19 September 2006 (UTC)
Ah, you're right. Clever. And that probe, you could even go down in it yourself. —Bromskloss 12:49, 19 September 2006 (UTC)
That's true, you can use gravity assist to get some "free" (it's not completely "free" as you alter the trajectory of the body you're passing near, but the effect is so small it can be ignored) acceleration or deceleration. However, you can't slow down very far this way, so you still have to shed the rest of your speed some other way, either with rocket engines or aerobraking, neither of which obviously nets you any energy. — QuantumEleven 15:09, 19 September 2006 (UTC)
What do you mean when you say that you can't slow down very much? Relative to the body you use for gravity assist, you can't slow down at all, actually. You can only change the direction of your movement. —Bromskloss 21:32, 19 September 2006 (UTC)
Gravity slingshots do address this when you can use them, but it's important to realize that you always have the problem of conservation of momentum. If you're going to stop when you get to Alpha Centauri, something else has to gain that momentum. If this is fuel that you carry with you, you'll have to give it energy to get it moving (in your reference frame). What you'd "want" to do would be push off of a counterweight you left behind at Earth, and then pull on it again when you got there. But this would require a light-years-long tether, or else some magic like a tractor beam, and so has its own problems. --Tardis 16:30, 19 September 2006 (UTC)
The reason it is impossible is that, even theoretically, energy will be lost (due to the second law).
Um, what do you mean? I can't see why you would loose energy (apart from practical imperfections, of course) or what Newton's second law has to do with it. —Bromskloss 21:32, 19 September 2006 (UTC)
Read the articles on the second law of thermodynamics and Newton's laws
The third answer is that, due to the absence of appreciable friction, accelerating an object in space requires using Newton's third law. (See the second paragraph in the Overview at rocket.) That is, fling something backwards away from the ship. Since the center of mass of the rocket/exhaust system is unaccelerated by this maneuver, if you want to travel arbitrarily great distances, you have to let the exhaust escape. Having done this, your ability to subsequently accelerate (to stop at the destination, for instance) is reduced because you have less stuff left to use as exhaust. If, for example, your exhaust were a lead brick and you attached an infinitely long, internally frictionless rope to it, you could throw it away at the start of a maneuver, then grab the rope at the end and recover (most) of your kinetic energy. But the example is strongly unrealizable except for very short maneuvers (say, the length of the capsule).
Semi-relatedly, there are very low energy transfer orbits in the Interplanetary Transport Network. Some of these transfers are free, and others are surprisingly low-energy. -- Fuzzyeric 19:01, 19 September 2006 (UTC)
If there is a large mass at the point of destination that can be used as an anchoring point, then you could stretch a large rubber band between two poles and have the ship fly into the band. Just as the ship would be about to be catapulted back, you secure the stretched band, storing energy. At departure time, use as a catapult. --LambiamTalk 21:19, 19 September 2006 (UTC)

Global Warming/ Ozone layer[edit]

Seeing as the ozone layer is closing, does that mean global warming will stop? If not, what does it have to do with global warming?


The hole in the ozone layer has nothing to do with global warming. The ozone layer is a region of the atmosphere that shields us from ultraviolet radiation coming from the sun, and prevents you from sunburning too easily and getting skin cancer (amongst other things). Global warming is the result of increased amounts of greenhouse gases (such as CO2) which 'trap' more of the sun's heat, changing the global climate. I recommend you browse through some of the articles I've liked to for more info. Hope this helps! — QuantumEleven 11:33, 19 September 2006 (UTC)
The confusion is that both are caused by air pollution. The hole in the ozone layer was caused by CFCs, which used to be in every spray can and air conditioner. They have been largely eliminated now due to government actions, and this explains why the ozone hole seems to be closing. The greenhouse gases which cause global warming have not been stopped, however, thus global warming continues to worsen. There are two main reasons why there is no agreement to reduce greenhouse gases:
  • The Bush administration is denying that anything needs to be done and has rejected the Kyoto Protocol, which would have addressed this issue.
  • Unlike CFCs, a significant portion of greenhouse gases are produced by third world countries, which can't afford to eliminate them. They are produced by agriculture, heating homes, etc.
However, since action on stopping the use of CFCs did fix the ozone hole, it's reasonable to think that reducing greenhouse gases would reduce global warming. We've now seen evidence that human intervention can affect the atmosphere, for good or for bad. StuRat 11:59, 19 September 2006 (UTC)
Sidenote: the fact that most greenhouse gas production takes place in third world countries is caused by the fact that those countries house the vast majority of mankind. DirkvdM 18:56, 22 September 2006 (UTC)
Of course the ozone hole had decreased in some years before CFC's were discontinued, and the Earth has been warmer than this before the industrial age began adding more greenhouse gasses. The Climate is more complex than many are willing to admit.
No no it wasn't. The ten year average is the highest in history, as far back as reliable estimates can be made via the current methods. And we are indisputably at the high point of recorded temperatures. --Darkfred Talk to me 16:22, 19 September 2006 (UTC)
Most people seem surprised when to find that current levels are relatively low, at least from a long-term perspective - understandable considering the constant media/activist bleat about current levels being allegedly "catastrophically high." Even more express surprise that Earth is currently suffering one of its chilliest episodes in about six hundred million years.[1] On the 650,000 year time scale, it is following pattern remarkably well.[2] On the 20,000 year time scale it is pretty hot.[3] Regarding post-Industrial Revolution[4], this is for sure the hottest time (how hot is disputed). However, the point is often brought up that only a few decades before the Industrial Revolution was the CO2 ppm measured as higher than current. (Thenard, 1812 Traité élém. de chimie, 5 edit., vol1, p. 303. | Value: 385.0 ppm) (W. Kreutz 1941, Kohlensäure Gehalt der unteren Luft schichten in Abhangigkeit von Witterungsfaktoren,” Angewandte Botanik, vol. 2, 1941, pp. 89-117 | Average 1939-41: 438 ppm) The current value is around 381 ppm. I see you have mentioned "as far back as reliable estimates can be made via the current methods"—that is where opinon comes into play often more than scientific objectivity.— [Mac Davis](talk) (SUPERDESK|Help me improve)16:53, 19 September 2006 (UTC)
The problem with examining the whole 650,000 year timescale is that different studies have had radically different results. As far as the last 20,000 years the results are undeniable. You mentioned C02 levels, according to ice cores testing, (where the granularity of testing is in 10-100 year range) we are at a 300,000 year high. The high 1800s numbers are during the heydey of Coal consumption, the problem is the numbers have never returned to their pre-coal/pre-industrial levels. By propping up the less reliable statistics you are basically just giving political ammunition to the "do-nothing" crowd, when there IS a concensus on the danger even from the scientists who have recorded the outliers. --Darkfred Talk to me 14:54, 20 September 2006 (UTC)
Although the Bush administration has its own motives for denying, there is an extremely heated controversy on almost all parts of the anthropogenic global warming hypothesis. Back to the original question, the ozone layer is a thin dynamic blanket that absorbs some parts of the ultraviolet spectrum. Relation to climate seems negligible at current. — [Mac Davis](talk) (SUPERDESK|Help me improve)16:46, 19 September 2006 (UTC)

While there have certainly been climactic variations in geologic history, that fact is unrelated to human-caused global warming, which most scientists and national governments accept as a serious problem. If the scenario is true, then failure to heed the warning signs in time would have serious consequences. Oceans could rise due to melting glaciers and ice shelves: just a few feet of rise could destroy the fresh water reservoirs for the country of Kiribati. The city of Venice would become uninhabitable. Other inhabited lowlands such as coastal Louisiana and parts of Florida would have to be evacuated. Durova 22:27, 19 September 2006 (UTC)

Climate change can be a serious problem [in some aspects] as you say, however it is not as if it is not going to happen if we stop CO2 emissions. — [Mac Davis](talk) (SUPERDESK|Help me improve)00:12, 20 September 2006 (UTC)
I'm going to be rude, and rather than refuting what you've said, Mac Davis, I'm going to suggest that you're buying in to tobacco and oil company sponsored propaganda. I don't know how you could say our CO2 levels are anything but at an all time high. By funding a large number of organisations, Exxon helps to create the impression that doubt about climate change is widespreadPengo talk · contribs 15:13, 20 September 2006 (UTC)
If only that were true... my friends sure wish exxon would pay them! [Mαc Δαvιs] (How's my driving?) ❖ 15:30, 23 March 2007 (UTC)

Also note that the rate of change of global temps is at least as significant as the current level of global temps. Normally, global temps would only change slowly, allowing people time to adapt (moving slowly inland as the coasts flood, for example). However, rapid change can lead to disasters. There may be some rare natural causes of such rapid temp changes, too, such as a supervolcano or large meteor. Of course, those events can be catastrophic to life on Earth too, just ask the dinosaurs (oops, you can't !). :-) StuRat 00:33, 20 September 2006 (UTC)

I would have to disagree that humans or climate change could cause a supervolcano or meteor impact. — [Mac Davis](talk) (SUPERDESK|Help me improve)04:00, 20 September 2006 (UTC)
Mac Davis, you are setting up a straw man here. No-one has claimed that humans or climate change causes a supervolcano or meteor impact. Gandalf61 14:50, 21 September 2006 (UTC)
I think he was joking. StuRat 04:05, 22 September 2006 (UTC)

Perspective viewpoint[edit]

What are the main gaseous products of volcanoes? And how much do they produce per year? Are these greenhouse gases? How much of these gases does the human race produce? 8-)--Light current 04:04, 20 September 2006 (UTC)
A clue: Volcanic activity releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year. SO2 output shown here: [[5]] Looks like at least 10 megaton per year to me --Light current 04:21, 20 September 2006 (UTC)
I believe SO2 is more 'greenhousey' than CO2 and water vapor is the worst! So how now?--Light current 15:21, 20 September 2006 (UTC)


does magma contain magnetic material?

It can. For example, moving molten iron can react with the Earth's magnetic field and cause a weak magnetic field to form. Most magma, however, is not magnetic. StuRat 11:49, 19 September 2006 (UTC)
Indeed. If there is some kind of metal in it. --Proficient 06:30, 21 September 2006 (UTC)
I don't believe that most metals can be magnetized. Only certain metals, like iron, can be. StuRat 04:03, 22 September 2006 (UTC)
Ferromagnetism--Light current 04:06, 22 September 2006 (UTC)

Fidel Castro's eyes[edit]

Why do the irises of Fidel Castro's eyes appear completely black in recent pictures? Does some drug dilate the pupils that much? If so, how can he stand daylight?


The man is barely alive. 'Intestinal surgery' usually means something really bad, like stomach cancer or some such thing. As well, he might be on a hose-pipe of morphine. --Zeizmic 12:59, 19 September 2006 (UTC)

the magnetic field can effect to FO ( mazut oil) using in burner[edit]

My manufacturer has one boiler made in UK, produced by Wellman Robey, this boiler uses FO (mazut oil) for burning, I make the maximum magnetic field by the Neodyme magnets in the input type of the oil line to the boiler , I hear that this system will be saved the oil after the magnet treatment ,but the oil used the same, not reduced. For the burner using the DO, it's OK, Why? Please give me the answer. Thanks. Ngocthuan_06 , 13:30 (UTC) 19,SEPT,2006

The "magnets on a fuel line" scheme is an urban legend at best. They never have any effect. There are, of course, countless shady companies with these worthless products. DMacks 14:17, 19 September 2006 (UTC)

I have the fuel saver from USA for the truck used the Diesel Oil, this product uses the magnet treatment for reducing the dimension of the fuel drop, from 300Micron into 3 micron, the fuel will be burned completely.The fuel reduced about 15% for my truck in highway You can find out it by go to, type fuel saver [[User:Ngocthuan_06] 14:30, 19 september 2006 (UTC)

I'm not really sure why you appear to be answering your own question, but DMacks has summed up the situation nicely. Magnetic "fuel savers" are hoaxes. If they weren't, they'd be standard equipment with every car manufacturer who likes bragging about fuel economy. — Lomn 15:57, 19 September 2006 (UTC)
The question posed (as I interpret it) was: "It works fine for diesel oil. Why does it not work for fuel oil?" --LambiamTalk 21:30, 19 September 2006 (UTC)
I think that any products are selling in USA, it must be checked the quality and purpose. I bought one fuel saver for fuel car, and one for truck, my truck is OK , it reduce 15% of DO in the highway, and 6% in city.But my car, it can not go over 70km/h, the speed can not increase but I still open the throttle(it means the fuel is increased but the speed is saturated), but if below 65km/h, it can reduce 20% of fuel in the highway. And now I get this for the FO burner, but no effect . I pose the question, why is it the difference of the same hydro carbon molecules but one is effected with magnetic field, one don't >User:Ngocthuan_06 00:51, 20 September 2006 (UTC)
The additive is reducing the octane of your fuel, destroying its performance while slightly increasing mileage rating. This will also damage your engine, your manual states a minimum octane. Plus, for a 6% increase in fuel efficiency (which I doubt) you are paying $15. This is NOT a good deal, you could simply have paid for 50% more fuel. --Darkfred Talk to me 14:59, 20 September 2006 (UTC)
because neither are being effected by the magnetic field. Xcomradex 00:18, 20 September 2006 (UTC)
Ayup. Can't rule out observer bias in the driving case: you know the magnet's there, and you unintentionally drive in a more fuel-efficient manner. OTOH, you could believe all this hooey, and think about the differences between what form of energy you get from a piston engine and a combustion furnace: maybe magnets increase the expansion that occurs during burning but don't increase the heat output. "I think that any products are selling in USA, it must be checked the quality and purpose" is entirely false—there are as many unscrupulous quack vendors selling useless, counterproductive, dangerous, and even illegal things are there are gullible people willing to pay for them. DMacks 01:53, 20 September 2006 (UTC)
indeed, i'm sure these[6] have been tested for "quality and purpose". Xcomradex 03:03, 20 September 2006 (UTC)

I am slightly embarrassed to say that I was taken in by the whole magnet thing; so much so that for 2 or 3 years I ran a site in the 90s called As I understand it, magnets have an effect at a molecular level, when the constituents of the material are POLAR - ie have a north and a south. For this reason magnets have an effect on water, and on anything containing water -like blood; as Hydrogen is polar. The problem with petrol or diesel is that it does not contain any significant elements that are polar. Therefore magnets just cannot make a big difference. I would like to know if this is correct, as we did independant tests on fuel savers a few years ago; which resulted in interesting stories. A rally car business did a bench test and found the magnetic fuel saver boosted engine performance a fraction. A taxi driver took his Toyota in for its annual MOT test, and they found the emissions way below normal. There were lots of stories like that, which makes me think there must be something in fuel that is affected by a magnetic field. Has anyone any ideas? pedro

Contact glue[edit]

I bought some superglue with instructions along the lines of applying glue to both of the surfaces to be affixed, waiting 10-40 minutes and then pushing both surfaces together. I want to know what is going on here - why can't I just apply glue to one surface, push the other suface against it and leave them overnight to get acquainted. --Username132 (talk) 14:12, 19 September 2006 (UTC)

The strength of the bond depends on the amount of pressure the two objects are under whilst the glue dries. The stronger the pressure, the stronger the bond.

What you're talking about isn't superglue, but a type of contact glue (I haven't found a Wiki page on it yet). I have used it for many years, and, yes, it does work best if you apply it to both sides, leave them both to dry for a little bit (10-40 min sounds good, less if the ambient temperature is warm) and then press them together hard. The strength of this type of glue depends on the force with which the two objects are pushed together. After you've pressed them together you then need to leave it for a bit to set properly. You can, of course, just apply the glue to one side, press the two together without waiting, and leave it overnight, it will still work, but the joint won't be as strong. — QuantumEleven 14:51, 19 September 2006 (UTC)
The products I've used call themselves "contact cement" and several wiki pages (including glue) have redlinks to contact cement as well. So I guess: 1) that's this thing's official name, and 2) we there isn't a wiki page for this thing. DMacks 18:51, 19 September 2006 (UTC)
The "why" is that glues set by evaporating solvent and polymerizing (or engaging in other, more complicated chemistry). If you press the parts together soon, then the evapoartion can take a long time and therefore the time to set can become unduly long (possibly infinite). -- Fuzzyeric 18:42, 19 September 2006 (UTC)
Rubber cement is a common name. Rmhermen 21:24, 19 September 2006 (UTC)
No, I'm afraid that rubber cement is something different again. I have used both, and they are very different beasts... — QuantumEleven 14:42, 20 September 2006 (UTC)

Rows of teeth...[edit]

An adult human can grow only 2 sets of teeth...Why is this? And why can animals (e.g. A shark), grow many sets of teeth?

Presumably, due to evolution. Some animals (i.e. shark, crocodile) lose their teeth a lot because they like to feast on large, live prey. They have to bite down on an animal struggling for it's life, and some of the teeth or lost. If the teeth didn't grow back, that would be one toothless shark. For humans, we don't have to worry about that problem. We never bother to grow teeth after they've been lost.— [Mac Davis](talk) (SUPERDESK|Help me improve)17:05, 19 September 2006 (UTC)
I've actually heard speculation that wisdom teeth were evolved in order to replaced lost teeth. This explains why many modern day humans don't have room for these teeth, because they haven't lost any others. --best, kevin [kzollman][talk] 19:29, 19 September 2006 (UTC)
I grew three sets. Maybe I should've feasted upon live prey while I had the chance. AEuSoes1 19:36, 19 September 2006 (UTC)
What do you mean, you don't do that now? *slurps in the last, gory piece of flesh* —Bromskloss 21:16, 19 September 2006 (UTC)
"and the people did feast upon the lambs and sloths and carp and anchovies and orangutans and breakfast cereals and fruit bats and large chu--" – b_jonas 14:21, 20 September 2006 (UTC)

I understand what you guys are saying, yet it still doesn't tell me why we don't grow more than two sets. IS there a reason? Or is it something no one can explain? Its very weird and I have no idea what the answer is! HELP MEEEEE!

It's not that humans don't grow more than two, it's that other animals do. We don't grow more because we don't need to. That is to say, evolutionary pressures are not sufficiently strong to have mutant genes like mine more reproductively advantagious. Although I do attribute my attractive set of straight cavity-less teeth to the fact that my last set came in when good dental hygiene practices were finally engrained into my prepubescent psyche. AEuSoes1 21:47, 19 September 2006 (UTC)
Are your last teeth falling out? What sense of "why" do you mean? After all, why don't we grow an extra set of eyes for when the first set starts failing? And why don't we grow a pair of eyes in the back of our heads? Why can't we fly? It's so very weird. WHY? WHY? --LambiamTalk 22:01, 19 September 2006 (UTC)
Evolution is based on epending the minimum amount of energy, whilst spending it well so that it increases the chances of survival to the point that it was worth the change. Since we have survived just fine as a species with only 2 sets of teeth, we have no need for any more. Philc TECI 22:08, 19 September 2006 (UTC)

I would say the cost of growing new teeth includes the possibilities of impacted teeth, infection, abscess, and death. We need to grow one new set of teeth, or else either babies would have impractically large teeth or adults would have useless tiny teeth. (I know someone who never got their adult teeth, and those baby teeth are almost useless as an adult.) But, growing more teeth would have more of a cost (potential death) than a benefit, so we don't do it. StuRat 00:01, 20 September 2006 (UTC)

Urrr, what? Naturally we grow a second set, and rarely (never) have I heard this result in death... Philc TECI 17:51, 20 September 2006 (UTC)
Just because you haven't heard of it doesn't mean it doesn't exist: [7]. It certainly happens more rarely now, however, because we have dentists. If we had them during the majority of human evolution, we may have evolved differently. StuRat 20:22, 20 September 2006 (UTC)
Also, baby teeth can be considered a temporary solution, as they are smaller, weaker, and take a much less firm hold on our gums than adult teeth do. Allowing succesive rows of adult teeth to grow in would certainly cause many more problems. I guess we should ask our resident freak AEuSoes1 how it worked out for him.  freshofftheufoΓΛĿЌ  01:45, 21 September 2006 (UTC)
As far as I recall, it was just a little embarassing to be losing teeth when I was eleven. I don't think that all teeth were replaced and I'd probably have to do a bit of investigation with my old dentist and his x-rays to see how many it was. AEuSoes1 08:19, 21 September 2006 (UTC)
Ok, my reply was a bit toungue in cheek, I dont doubt that it could kill you, but then everything can kill you, it just doesnt, because its unlikely. And there must have been an evolutionary advantage of early humans with 2 sets over the ones with one set, one thing is your jaw changes shape dramatically from when your first teeth form, to when your second set do. Philc TECI 21:51, 22 September 2006 (UTC)
There are many things that have killed people throughout most of our evolutionary history, that kill very few people today. For example, a broken leg would have pretty much been a death sentence long ago. If you didn't die from infection and it somehow managed to heal, the deformity would have made you unable to hunt, migrate, etc., and, before a social welfare system existed, you would have been left to starve. StuRat 09:26, 29 September 2006 (UTC)

Ear Throat connection - Eustachian Tube[edit]

If a very bitter oily liquid is dropped in the ear, can It taste bitter in the mouth?

Depends if the molecules can permeate the eardrum somehow (or you got a perforated eardrum). Otherwise I would say no.--Light current 15:33, 19 September 2006 (UTC)
Are you saying that if a bitter liquid somehow got past the eardrum, a bitter flavor would be tasted? Do you have a source for that? It is interesting if true, and if so I'd like to read more about it. Gary 00:16, 20 September 2006 (UTC)
No source. Its obvious that if the stuff get beyond the eardrum into in the eustachian tube that leads to the throat anh hence to the mouth nose etc. Therfore you may taste/smell it.--Light current 00:41, 20 September 2006 (UTC)
No, it isn't going to happen. — [Mac Davis](talk) (SUPERDESK|Help me improve)16:42, 19 September 2006 (UTC)
Many people have a perforated eardrum. Via the Eustachian tube, material from the external ear can enter the mouth and be tasted. Contrariwise, some of them can puff on a cigarette and blow smoke out their ear. Edison 04:54, 20 September 2006 (UTC)
Here's your reference:

the middle ear lies in the petrous part of the temporal bone. It contains the three ossicles. Laterally lies the tympanic membrane (eardrum). Medially lies the inner ear. … Anteriorly, the Eustacian tube communicates with the pharynx. Oxford Hadbook of Clinical Specialties 4th Ed. 1995. ISBN 0-19-262537-3

So, yes, things can pass from the middle ear to the pharynx, and thereby the mouth, where they may be tasted. If the eardrum is perforated, it follows therefore things placed into the external auditory meatus (ie your earhole) will be able to be tasted should they pass through to the mouth. The quandry arises in the case of an intact eardrum - how do you get the taste to go through? Light current's idea of permeation is interesting, but I don't know that enough would get through to have an appreciable taste in the throat - so I don't think that's the whole story. My theory is neurological. The mucous membrane of the middle ear is supplied by a bunch of nerves called the tympanic plexus, which mainly originates from the tympanic branch of the glossopharyngeal nerve, and, you guessed it, the glossopharyngeal nerve also carries sensory information from the pharynx and the posterior ⅓ of the tongue. That is, a lot of taste information gets to the brain via the glossopharyngeal nerve. Now, here's where Light current's idea kicks in. Any substance that can diffuse through the eardrum, (and it really only has to get to the inner surface of the eardrum, which is covered by the mucous membrane of the middle ear, and therefore innervated by the glossopharyngeal nerve) might cause a degree of chemical irritation to the mucous membrane, which would generate a sensory impulse the brain could well interpret as a taste - the brain's differentiation of smell, taste and oropharyngeal stimuli being a bit fuzzy. --Mattopaedia 13:30, 20 September 2006 (UTC)

Gold reacting with Mercury[edit]

Dear Sir, Gold whien in contact with Mercury is changing the colour to silver. What is to be done to get back the colour of Gold. With Regards, Ajaya Babu Potluri

The gold metal isn't just turning a silver color, it's actually dissolving in the liquid mercury, forming an amalgam. The "Mining" section of that article mentions distillation as a way to remove the mercury. Google for gold mercury separate for more info. DMacks 16:19, 19 September 2006 (UTC)
Is this a homework question of a practical question, if practical DO NOT attempt to repair this yourself, you are obviously not a metallurgist, attempts to do this at home could result in permanent brain damage. --Darkfred Talk to me 16:26, 19 September 2006 (UTC)
Then all youll be fit for is WP ref desk work. Like us! Duh! 8-)--Light current 20:51, 19 September 2006 (UTC)
Huh? whuaa? --Darkfred Talk to me 21:29, 19 September 2006 (UTC)
Stop sniffing that mercury vapor--Light current 21:34, 19 September 2006 (UTC)
my mercury tastes funny. Xcomradex 21:40, 19 September 2006 (UTC)
Yeah, it seems a bit off to me too. Better switch to some of that sweet sweet lead. DMacks 21:48, 19 September 2006 (UTC)
nothing beats a shot of gallium on a warm summers day Xcomradex 22:52, 19 September 2006 (UTC)
Hey, it worked for Isaac Newton, allegedly. Confusing Manifestation 01:06, 20 September 2006 (UTC)
In seriousness now. If this is damage to a family heirloom cause by breaking a thermometer, a jeweler could fix this by reforging the item, basically heating it till it glows, the mercury will boil off. This should be done under a vapor hood, while wearing a mask. --Darkfred Talk to me 23:00, 19 September 2006 (UTC)
The title is wrong, isn't it? Nether Gold nor Mercury react very well, let alone with each other. It's an alloy, not a chemical reaction. DirkvdM 08:57, 20 September 2006 (UTC)

You guys are wimps, I swallow a 2 kilogram pellet of plutonium daily. Builds character --⁪frothT C 02:48, 27 September 2006 (UTC)

So it was you that dropped a bonb in the men's room after we has Mexican for lunch! DMacks 02:52, 27 September 2006 (UTC)


Is Satellite a Vector?

from Hatim Bharmal email address: <email removed to prevent spam>

Could you give us some context? It may be helpful. — [Mac Davis](talk) (SUPERDESK|Help me improve)18:58, 19 September 2006 (UTC)
Do you mean is an artificial satellite a biological vector? Peter Grey 20:36, 19 September 2006 (UTC)
In none of the meanings of satellite that I'm aware of is it a vector in any of the senses I know. (One meaning is the Satellite moth species, which in theory could be a disease vector, but is not as far as I know.) --LambiamTalk 22:14, 19 September 2006 (UTC)
A satallite has vectors, like a velocity vector and an acceleration vector! --Amanaplanacanalpanama 00:32, 20 September 2006 (UTC)

I'm going to interpret the question as "do satellites in orbit travel along a constant vector (straight line) ?". In that case, under Newtonian physics, the answer in no, they follow an elliptical orbit. According to relativity, however, I believe space is curved (by gravity) around massive objects like planets, and the path they follow is actually straight, so could be called a "vector". StuRat 14:55, 20 September 2006 (UTC)

Even if you didn't consider relativity, would it be un-scientific to imagine an elliptical vector for the satellite?  freshofftheufoΓΛĿЌ  01:39, 21 September 2006 (UTC)

laws of motion[edit]

if you were to push an immovable object with all your might, how hard would it push back?

With the exact same force as you were applying to it. However, this would never really happen so I suppose you could say it could push back with any force as it is outside the scope of the laws of physics (as far as I know) 20:08, 19 September 2006 (UTC)
See normal force. — [Mac Davis](talk) (SUPERDESK|Help me improve)20:20, 19 September 2006 (UTC)
Unless the questioner is addressing God, then Irresistible force paradox would be the article to see. —Bromskloss 21:11, 19 September 2006 (UTC)
See Newton's laws of motion. It's not possible to have an immovable object. By Newton's 2nd law, if you apply a force to an object, it will accelerate. By Newton's 3rd law, it will push back as hard as you push it - as the first reply said. Whilst it's not possible to have an immovable object, it is possible to have an extremely heavy one, say a large wall connected to the Earth - where the acceleration caused by your muscular force will be miniscule. Richard B 21:49, 19 September 2006 (UTC)
Presumably you'd be pushing the Earth with your feet in the other direction with the same force. Otherwise, you'd also be accelerating in the opposite direction. So effectively you're keeping the Earth in its place. --LambiamTalk 22:19, 19 September 2006 (UTC)
If you take the reference frame of the object (so it doesn't seem to be changing its motion), if you push on the object, it would appear to push back with more than the force that's pushing it. It also would seem like the entire universe accelerated - but that's only because your reference frame is accelerating. An accelerating frame of reference makes things strange. —AySz88\^-^ 22:35, 19 September 2006 (UTC)

Anyone can move the Earth by jumping up and down. Of course, the planet will move a smaller distance than the person. Edison 04:56, 20 September 2006 (UTC)

Yes, but it's not like the Earth moves all at once as a rigid body. It's probably better to say that anyone can launch seismic waves into the Earth by jumping up and down. Melchoir 05:43, 20 September 2006 (UTC)
Also, the Earth and you would move back to the same position due to the gravitational attraction between you, no? 16:16, 20 September 2006 (UTC)

"Protein molecules of the ninth configuration?"[edit]

In the movie The Ninth Configuration, a character says:


So I have a couple questions. What exactly is a protein molecule of the ninth configuration? Do we have any articles that talk about these kinds of proteins specifically? And does anyone know if what the character claims has been proven/disproven/discounted since then (the book the movie is based on was written in 1978)? Recury 19:56, 19 September 2006 (UTC)

I have no clue what the character in the movie is talking about, but you might be interested in the article Origin of life. --Allen 20:28, 19 September 2006 (UTC)
I have never heard of a protein molecule of the ninth configuration. I am thinking this figure comes from the 9 human essential amino acids. Also, the figure cited I would think is not very reliable ("the kind that you make up, not look up"). Besides, it wouldn't take that long for a few atoms to hook up in the right way—that's 10251 years. That's several orders of magnitude greater than the estimated lifespan of the universe. Heh. — [Mac Davis](talk) (SUPERDESK|Help me improve)20:31, 19 September 2006 (UTC)
Probably fictional. Peter Grey 20:33, 19 September 2006 (UTC)

It might be useful to look at what the Intellegent Design folks have to say about this. This is a film, and the purpose of films are to entertain, although they can have the effect of provoking thought. I always ask people who calculate these odds exactly how did they do these calculations. How do you compute the odds of something when you do not know what the conditions are. What are the odds of rolling dice and coming up seven? What are the chances of throwing a peice of metal in water and having it catch fire? What are the chances of a planet existing with an oxygen atmosphere? How do you calculate these odds without knowing the conditions?

You don't, because of the randomity, the ignorance. I tried to keep from saying the number was bullshit, but I guess it is evident. — [Mac Davis](talk) (SUPERDESK|Help me improve)21:21, 19 September 2006 (UTC)
thats mostly bollocks (nineth configuration??) wrapped around an actual nugget of truth, the Levinthal paradox. Xcomradex 21:37, 19 September 2006 (UTC)
Having read the essential amino acids and Levinthal paradox articles, it seems pretty likely to me he is applying the Levinthal paradox to essential amino acids to make his argument for ID. If my memory of the film is right, he does mention that the amount of time it would take is longer than the lifespan of the universe, which I guess is the point of the argument. Which "configuration" is supposed to be ninth out of nine is beyond me. Recury 22:07, 19 September 2006 (UTC)
which, as mentioned in the levinthal paradox article, is a pretty weak argument. Xcomradex 22:51, 19 September 2006 (UTC)

In addition to the other flaws already mentioned, limiting the places where life could possibly evolve in the universe to just Earth is also wrong. Life could evolve anywhere in the universe with the proper conditions. Had it evolved somewhere else, instead of on Earth, we would be on that planet and the silly ID folks there would then limit their calcs to that planet, and not include Earth as potential site for life to evolve. StuRat 23:51, 19 September 2006 (UTC)

But it most likely wouldn't be "us." Some "thing" else. — [Mac Davis](talk) (SUPERDESK|Help me improve)04:39, 20 September 2006 (UTC)
But whoever is there would think of themselves as "us". StuRat 14:37, 20 September 2006 (UTC)
Although of course, depending on the conditions on that planet, the might not actually think of themselves as "us" because such ideas may be too complex for them (but I otherwise agree with your point). Nil Einne 16:55, 28 September 2006 (UTC)

Science Projects on the Titanic[edit]

i have been trying to find examples of science projects on the Tiatance for 4th grade. Can this site help me?

Yes it can probably. Next question?--Light current 21:44, 19 September 2006 (UTC)
  • I'd say something about buoyancy is probably what you will be looking for. - Mgm|(talk) 21:53, 19 September 2006 (UTC)
Depends whether the questioner is looking for something about the sinking, or about the design of Titanic. We need more info from the questioner.--Light current 21:56, 19 September 2006 (UTC)

Icebergs could be a good topic for a fourth grade science project. Durova 22:16, 19 September 2006 (UTC)

Attempt to build a lifesize model out of popsicle sticks! You can go half size if you are lazy. — [Mac Davis](talk) (SUPERDESK|Help me improve)22:37, 19 September 2006 (UTC)
(meta) What surprises me is that Google gives me three hits on "tiatance". (/meta) An interesting angle might be the cold embrittlement of materials. This was relevant for the Titanic (see RMS Titanic#Faults in construction) and much more recently for the Space Shuttle Challenger disaster (see Richard Feynman#Feynman's later years). Feynman's icewater and O-ring demonstration is probably more feasible for a school science project than would the equivalent iron embrittlement demonstration, but the basic science is similar. -- Fuzzyeric 23:22, 19 September 2006 (UTC)
You could do something on the searching for, recovering, identifying and forwarding of remains (then vs. now). [8] - Nunh-huh 23:31, 19 September 2006 (UTC)Edison 05:00, 20 September 2006 (UTC)

Build a spark transmitter and send Morse code signals. Measure how much of a block of ice floats below salt water.Edison 05:02, 20 September 2006 (UTC)

redox reaction help[edit]

can someone help me, i need to predict and balance the reaction k+ s8---> i just need the products, thanks-- 22:40, 19 September 2006 (UTC)-- 22:40, 19 September 2006 (UTC)

This isn't the homework-helpers'-hut, mister. I'm wondering, is that a potassium ion (K+) or the potassium metal (K2)? I haven't worked with theoretical redox equations in a year so I might be wrong in thinking that it should be either one. Hyenaste (tell) 23:21, 19 September 2006 (UTC)

Dude, we don't do your homework for you. Try the redox reactions page. It shows you how to do it. And make sure you get different charges at the end. Potassium should be oxidized and sulfer should be reduced.

Is potassium metal K2? i did not know that, and can't help but suspect it false. why does elemental potassium exhibit metallic properties on the bulk scale if the bonding is localised into K2 units? these bulk properties suggest delocalised bonding, like the other metals. Xcomradex 00:16, 20 September 2006 (UTC)

Oops, I was wrong. I saw a K and S and jumped straight into K2SO4, got frustrated with my inability to still be able to solve it in my head, and my response fell apart from there. Hyenaste (tell) 00:32, 20 September 2006 (UTC)

Hint: knock off the O's and you're done i'd say. Xcomradex 00:53, 20 September 2006 (UTC)

16K + S8 → 8K2S? Hyenaste (tell) 01:02, 20 September 2006 (UTC)

That would be my answer. Xcomradex 01:25, 20 September 2006 (UTC)


who invented the car?

See Automobile... many people invented the parts necessary for it, and carriages already existed so it is complicated. --Darkfred Talk to me 22:43, 19 September 2006 (UTC)
I don't think it was invented. I think it evovled over time. Have you checked the article Car? Himanyo 22:47, 19 September 2006 (UTC)
copycat :) --Darkfred Talk to me 23:03, 19 September 2006 (UTC)
Most cars did indeed evovle; only Volvos evolved. :--) JackofOz 23:08, 19 September 2006 (UTC)
Did not! Clearly cars, like television, represent intelligent design and content. Thus cars and television were invented by God and anything found in or on them is the literal truth of God. (<sprain> Ouch!) -- Fuzzyeric 23:26, 19 September 2006 (UTC)
Karl Benz in 1885 received a German patent for adding a gasoline engine to a carriage. More specifically for making and selling it to the public, but custom carriages had already been made by others, and steam cars were commercially available even earlier. --Darkfred Talk to me 23:14, 19 September 2006 (UTC)