Alex- That's a nice experiment. The idea is this. Hot water is a little
less dense than cold water. That means that the same weight of water
uses up a little more space when it's hot than when it's cold. Most
materials are like that- they take up a little more room when they're
hotter, because the atoms and molecules jiggle around more and don't
stick quite as tightlt to each other.
Denser things sink into less dense things. That's why steel will
sink in water but styrofoam will float on top. So you can see that the
hoter water should float on top of the cold water- which is just what
you actually saw. When the cold water is on top, it sinks. Maybe it
breaks up into little streams as it sinks, helping mix the green dye
around.Anyway, a lot of the green dye will make it toward the bottom.
Mike W.
(published on 10/22/2007)
