Date: Sun, 10 Oct 1999 21:59:03 -0400 (EDT)

Author: Richard Berg

Subject: Re: Ball jumping out of water cup


I don't believe it works that way. Buoyancy is the issue. The ball and
the water are both weightless when it is falling, and when it stops the
buoyancy situation is the same as when they were initially at rest before
they were released, so the ball will always remain in the same position
relative to the surface of the water. Look at

Dick Berg

On Sat, 9 Oct 1999, Urs Lauterburg wrote:

> Dear TAPlers,
> One of our Profs wants to show how a ball would be ejected out of a cup
> filled with water when dropped. He says he heard it should be possible but
> all I have tried so far failed. The idea is to have a ball float inside the
> water and when the water cup hits the floor the ball is supposed to be
> ejected due to the suddenly changing water pressure at the moment of the
> impact which should force the ball to fly back up again.
> Has anyone achieved this and if yes how ?
> Thank you for any related comments on this subject.
> Cheers
> Urs
> Urs Lauterburg
> Physics Edutainer
> University of Bern
> Switzerland