5. Before a serve, Roger Federer drops a 56 g tennis ball from a stationary height of 1.30m. The tennis ball falls to the ground and rebounds to a height of 1.05 m. (a) How much mechanical energy was lost during the collision with the ground? (b) Define what a non-conservative force is, and calculate the work done by the non-conservative forces on the tennis ball. (c) Typically tennis players bounce the ball before a serve to focus and find rhythm. Roger Federer applies a constant force downwards on the ball of 6 N, so that it bounces back to its original starting height of 1.30m. Calculate the distance d over which he must apply this force.