Sounds like the net force acting on the ball before and after is zero, so no change in the r. Is there a temperature change?
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From: email@example.com on behalf of Fakhruddin, Hasan
Sent: Mon 10/4/2010 1:31 PM
To: Forum for Physics Educators
Subject: [Phys-l] Clarification: A ball at the center of a planet
Alright folks, Here is a little modification:
A solid elastic rubber ball is a perfect sphere of radius r in free space. A solid homogeneous spherical massive run away planet also in free space has a spherical cavity formed at its center. The cavity is much larger than the ball and has vacuum in it. The ball is now transported to the center of the planet. Its radius now is
(A) > r
(B) < r
(C) = r
(now come on....don't ask me to define free space)
How did you guys ever take any exam without giving your instructor ulcers?!
'Burp'....excuse me; I just took Alka-Seltzer!
~ Hasan Fakhruddin
Instructor of Physics
The Indiana Academy for Science, Mathematics, and Humanities
Ball State University
Muncie, IN 47306
Forum for Physics Educators