- #1

Bernie G

- 330

- 13

“In the case of a spherically symmetric mass distribution we can conclude (by using a spherical Gaussian surface) that the field strength at a distance r from the center is inward with a magnitude of G/ r^2 times only the total mass within a smaller distance than r. All the mass at a greater distance than r from the center can be ignored.”

Proofs or explanations of this make sense, but I have a problem with the following scenario:

Suppose an object P orbits directly above a spherical mass M of constant density and radius R, and the object P only reacts gravitationaly with this constant density material. Then suppose the constant density material is extended to infinity. Should the object P still continue to orbit at radius R, since it is supposedly only affected by the mass within R? It seems under the new circumstances that P should move in a straight line.