Bill and his daughter Susan are both standing on identical skateboards (with really good frictionless ball
bearings), initially at rest. Bill weighs three times as much as Susan. Bill pushes horizontally on Susan's back,
causing Susan to start moving away from Bill. Just after Bill stops pushing,
A) Susan and Bill are moving away from each other, and Susan's speed is one-third that of Bill.
B) Susan is moving away from Bill, and Bill is stationary.
C) Susan and Bill are moving away from each other, with equal speeds.
D) Susan and Bill are moving away from each other, and Susan's speed is three times that of Bill.
