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Originally Posted by Richard M
Um, are you serious?
How would the sea level not rise?
And quite how you worked out that an ice cube melting in a glass of water would not raise the water level is beyond me, unless you watched it for so long that the water evaporated.
Hope that flameproof suit works well.  |
If you think about it it actually makes perfect sense.....sort of.....
If you take 2 one litre containers and have one full of water and the other full of ice (by full, I mean filling the entire space within the container with no room inside for anything else). You will find that the one containing the water is heavier.
The reason for this is that as water cools (actually, as water cools past 4 degrees celsius) it becomes
less dense (the connetions between the molecules actually start to expand again rather than continuing to contract).
So, something floats because it is less dense than the thing in which it is floating (ice is less dense than water). We also know that an object floating in a liquid will displace a quantity of that liquid which is equal to its volume.
We have a situation now where we have two things to consider.
1: If we put our 1 litre containers into a pool of water one at a time they will displace the same amount of water (ie that they will cause the level of water in the pool to raise by an equal amount) but.....
2: We know that there is less water in the container which has ice in it than there is in the one that has just water in it.
Now remove the containers from the equation but leave the contents. Initially the two water levels will be the same (they have both displaces equal quantities of water and so they have raised the levels by an equal amount). But, as the ice melts its volume will decrease. We know that the container holding the ice had less water in it so it stands to reason that there is now less water in the pool that we put the ice into than there is in the one that we put the water into.
The point here is: Putting an ice cube into a glass of water
will raise the level of the water
but as the ice melts it will revert to water which will take up less volume, therefore the displacement of the original water in the glass will be less, therefore the water level will fall (although it will still be slightly higher than it was before you put the ice in).
Does that help at all? Sorry it's long-winded and complicated, it took me a while to get this straight - oh, and it is
stupidly late as well
