Snow and physics
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Eddy Vluggen wrote:
The way you're explaining it, it's not a different representation, but a conversion. Something like going from HTML to RTF.
It's a conversion, it's deterministic macroscopically, and it has a rather simple (but not too simple) conversion function. Sort of like a
switchwith 3 cases per transition. Check this: http://en.wikipedia.org/wiki/Cooling_curve[^] This graph shows what happens to the temperature of a material(the temperature is related to the mean kinetic energy of the molecules, irrespective of state) as it goes from liquid (far left, smooth decline) to solid (far right, smooth decline again). Notice the sharp angle and the plateau that occurs at "freezing" temperature. Sharp angles in physics denote violent changes. Here, when the liquid (say, water) reaches this temperature (for water, 273 Kelvin), the temperature in the water stops dropping although we continue to pump heat out of it (by using e.g. a freezer). In this transient state, both ice and water co-exist, as some molecules have so little internal energy left, that the binding forces that keep them together forcefully bind them to a lattice, stopping any "attempt" to escape or move freely. Other molecules still have enough energh to overcome this attraction, and still move as if they're liquid. The heat taken from water to convert it from water of 273 Kelvin (or 0C, or 32F) to ice of the same temperature is called latent heat, and it's a distinct characteristic of the material itself. A similar curve exists for the transition between liquid and gas. The funny thing is that under pressure, the width of the plateau in that graph changes, and also the temperature at which it occurs changes. For instance, gas inside a can of spray is at such high pressure, that even in room temperature, it's a liquid. Above a certain value of pressure (dependent on the material as well) it actually vanishes. At such high pressure, it makes no sense to talk about gas, liquid or solid state. There's no real distinction between the three. We believe that this is what goes on deep inside the gas giant planets of the solar system. By the way, it's fun th check out the qualities of superfluids[yiangos wrote:
Sort of like a switch with 3 cases per transition
That "sort of" made me somewhat uneasy, but you were referring to the number of states that a substance can have. And there are more states than the three that I learned at school. ..but liquids that climb up a wall and "escape" from a cup? Sounded more like voodoo than physics! Thanks for the explanation :)
I are Troll :suss:
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I got caught in a UK blizzard* on my way back from school, and that got me thinking. A microwave oven uses microwave radiation, bounced around in a box, to defrost food by the evaporation of water molecules. Would it be hypothetically possible, with a somewhat larger energy expenditure, to turn the concept 'inside out'? What I mean by this is having a device which is effectively a very powerful microwave emitter. It would melt the snow (although I wouldn't want to use it - it would probably eventually cause deep tissue damage) fairly quickly if a microwave oven is anything to go by. And if I made a few guesses, I'd think that I could make it directional so that it could melt snowballs in midair given enough power. Before I go and burn most of the hair from the surface of someone else's arms, would this be physically possible? *UK blizzard: a faint sprinkling of semi-crystallised water, which causes local governments to use up all the grit. Sometimes followed by a significantly larger dump which causes the Daily Mail to whinge.
OSDev :)
It's possible to use microwaves to melt snow, but you wouldn't be able to just turn the microwave oven inside out, that could take hours, if it did anything at all. :( As for the snowball, you would need A LOT of power to melt it that fast, and it would have to be focused all on the same point... Fun idea though :) Oh, another thing too, if you were planning on building something like this, just know that microwave ovens have gigantic capacitors in them (to create the radiation), which is not good if you happen to be taking one apart. :( That raccoon started it.