A student drops a small ball from a height. The ball falls, hits the ground, and bounces back upwards.

Describe the motion of the ball between points A and B.
What direction is the ball moving between points C and D?
The ball and the Earth form a system. What is meant by 'a system' in physics?
When the ball hits the ground, energy is transferred from the ball to the Earth and surroundings. Explain how the data in the graph shows this energy transfer.