Gravity Problem 1

Animation 1 Animation 2 Animation 3 Animation 4

Description

A very wealthy individual proposes to dig a hole through the center of the Earth and run a train (the small black circle) from one side of the Earth to the other as shown in the animation (position is in Earth radii and time is in seconds).  Ignore frictional effects and assume the Earth is a uniform mass distribution.

Question

Which of the animations correctly depicts the motion of the train?

2000 by Prentice-Hall, Inc. A Pearson Company