Chapter P.2, Problem 20P

Teeing Off

A golf club has a lightweight flexible shaft with a heavy block of wood or metal (called the head of the club) at the end. A golfer making a long shot off the tee uses a driver, a club whose 300 g head is much more massive than the 46 g ball it will hit. The golfer swings the driver so that the club head is moving at 40 m/s just before it collides with the ball. The collision is so rapid that it can be treated as the collision of a moving 300 g mass (the club head) with a stationary 46 g mass (the ball); the shaft of the club and the golfer can be ignored. The collision takes 5.0 ms, and the ball leaves the tee with a speed of 63 m/s.

If we define the kinetic energy of the club head before the collision as “what you had to pay” and the kinetic energy of the ball immediately after as “what you get,” what is the efficiency of this energy transfer?

A. 0.54

B. 0.46

C. 0.38

D. 0.27