A jar filled partially with water has an object floating in it. The jar is open. Now, if the jar is closed and a vacuum pump is used to pump the air out, what will happen to the floating object? will it rise up more or sink or ...? and why?

(In reply to re: I think... by Vinod Kagal)

"For a floating object the upthrust exerted by the fluid is equal to the weight of the object, which has not changed."

But before the pump was applied, part (albeit a small part) of that weight was matched by displaced air.  Now that small portion will have to be matched by a little bit more displaced water, and in order to displace more, the object must lie lower in the water.

Posted by Charlie on 2005-07-22 17:45:45