I believe the radius will decrease due to the planets pull on the particles of the ball, directed toward the center of the planet.
So Choice C.
~ Hasan Fakhruddin
Instructor of Physics
The Indiana Academy for Science, Mathematics, and Humanities
Ball State University
Muncie, IN 47306
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Fakhruddin, Hasan
Sent: Monday, October 04, 2010 1:32 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
Phys-l@carnot.physics.buffalo.edu https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l