Lets see who gets this right.

You are sitting in a boat in a swimming pool with a rock inside.

You throw the rock overboard and it sinks in the swimming pool.

What happens to the water level? Does it decrease/increase/stay the same?


This post was edited by flyjum on Oct 29 2009 10:09pm

No idea, I said fall bcus the volume of the boat far greater then the rock. But since it sits on top, it's applying more pressure which the Water level is still high. But since the rock falls all the way to the bottom, its not exerting any pressure but the rock defnitly takes up less volume in the water vs the pressure its exert ing, so the water level has to drop. I think it really depends, if you have some #'s, like the volume of the boat, weight of boat, weight of rock, and volume of rock, then we can check :-)

the water will rise by the amount of volume displaced. it depends how much the rock "sank" the boat compared to how much water the rock displaces. if the rock is very dense it might push the boat farther down and displace more water. if its not very dense it will not displace much water in the boat, but displace alot of water when its thrown in

I voted it falls, but don't really care enough to find out the actual answer.

Water level falls. When the rock is in the boat, it displaces its mass in water. 1 cm^3 for every gram. When it is dropped in the water, it displaces its volume. As long as the density of the rock is greater than that of water, the water level will fall when the rock is submerged.

Duh.

Counter question: Take a tall glass and place a large ice cube in it. The cube is floating. Once the ice cube melts completely where is the water level compared to the start?

This post was edited by Sioux on Oct 30 2009 01:35am

stays the same

depends on the volume of the ice cube and also how much fluid is in the tall glass.

actually it depends on the density of the ice cube , not the volume .

stays the same because I remember a story about Archimedes and him proving that a crown was gold or not because the amount of water displaced was in relation to mass. So well it just makes sense to me, it would stay the same.