posted by crystal .
a child bounces a superball on the sidewalk. The velocity change of the superball is from 23m/s downward to 14m/s upward. if the contact time with the sidewalk is 1/800s, what is the magnitude of the average force exerted on the superball by the sidewalk?
List the formulas your teacher has you use, so I can solve it using methods that you are familiar with.