Question

A tennis ball traveling horizontally at 22.0 m/s suddenly hits a vertical brick wall and bounces back with a horizontal velocity of 18.0 m/s

Answer 1

This problem has three parts.

I enclose a pdf file with the three body diagrams requested.

Here is an explanation of them.

Part A: Make a free-body diagram of this ball just before it hits the wall.

The only force acting on the ball is the pull of the Earth, this is its weight; so the diagram is a vertical vector downwards.

Part B: Make a free-body diagram of this ball just after it has bounced free of the wall.

Again, the only force acting on the ball is the pull of the Earth, its weight, and the free-body diagram is identical to that of the part A.

Part C: Make a free-body diagram of this ball while it is in contact with the wall.

When the ball is in contact with the wall, two forces act over it: the reaction of the wall, which is represented as a horizontal vector toward the left, and the gravity (weight), which is represented as a vertical vector downwards.