[jp.101]

A rock sits in the bottom of a boat, which is floating on the surface of a pond. if the rock is thrown overboard into the pond, determine whether the levle of the pond would rise, fall or remina unchanged?

Any help on this would be greatly appreciated.

JP

[Borek]

What volume of water it displaced before and after stone has been thrown to water?

[nj_bartel]

Hint: assume the rock isn't pumice.

[jp.101]

I am not sure if the volume the rock displaces is equal to the incremant in volume from the rock in the boat....

[Borek]

No idea what you mean. Assume rock has known volume and mass (or mass and density, or volume and density, that's the same).

What volume of the water will be displaced by the boat, when rock sits in the boat?

[plat_num]

This is a quesion Microsoft asks on one of it's entrance tests.  You have to know more information then what you've given to answer the question.

[nj_bartel]

No you don't.  Not as long as you assume the rock is denser than water.

[plat_num]

You're wrong I believe.

Two rocks can have the exact same dimensions and therefore displace the same amount of volume when thrown overboard, but while in the boat the heavier rock will cause the boat to displace MORE water then the lighter one, since the heavier rock will cause the boat to be submerged deeper then the lighter rock. 

This also means that you could have a large rock that's JUST a little denser then water (which will displace a large volume when dropped into the water) yet doesn't displace too much water when it's in the boat since it doesn't cause the boat to submerge too much or you could have a small rock, incredibly dense, that will not displace as much volume when dropped into the water, however when IN the boat causes the boat to displace a large amount of volume. 

Depending on the various characteristics of the rock and boat the level of water could rise, fall or stay the same.

[nj_bartel]

You're ignoring one of my points.  If you're to assume that the rock is denser than water (a very, very safe assumption in these types of problems), then the rock will displace more water sitting in the boat than it does submerged in the water.