Velocity vs. time graph from Distance vs. time graph

Author:
alfinio
Derive the graph for velocity vs. time from the distance vs. time graph.
The upper graph represents the motion of a bouncing ball, distance vs. time. The distance is measured from the ground up. When the ball moves upwards, the velocity is positive. Move the points M, N, O, P, Q, R so that the segments DM, NO, and PQ represent the velocity of the ball in the air.
Move the points M, N, O, P, Q, R so that the segments DM, NO, and PQ represent the velocity of the ball in the air.