| MadSci Network: Physics |
Dear Wayne,
My guess is the answer that's being looked for here is, "the can will crush.' The hot air over the water is very spread out from the heat (which is why it's light, which is why it rises). If you cover the tin and allow the water _and_air_ to cool down, the air will cool and contract, lowering the pressure in the tin. If it lowers enough, the partial vacuum will collapse the walls of the can!
I've done this, with a rectangular metal kerosene can (no kerosene, though!). If you boil a little water in it, then screw the lid on tight and remove it from the flame, the can'll collapse in five minutes or less. -Jim Moskowitz