A student drops a ball from a balcony. The ball hits the ground and bounces. Figure 1 shows the velocity-time graph for the ball from when it is dropped until it reaches the maximum height of its first bounce. Air resistance is negligible. 
Describe the motion of the ball between points A and B on Figure 1.
What direction is the ball moving between points C and D on Figure 1?
The ball and the Earth form a system. What is meant by 'a system'? Select one option:
When the ball hits the ground, energy is transferred. Explain how the data in Figure 1 shows that energy is transferred from the ball to the surroundings during the bounce.