Question

A 60-g tennis ball moving at 8m/s strikes a stationary tennis racket perpendicularly and bounces off at 6m/s. The impulse given to the racket is?

Answer 1

Apply momentum conservation principle: initial momentum of the racket is zero, initial momentum of the ball is its speed times mass. The final momentum of racket is what we are to find, the final momentum of the ball is 6 m/s times its mass:

$$8\cdot0.06=p_\text{racket}-6\cdot0.06,\\ p_\text{racket}=0.84\text{ kg}\cdot\text{m/s}.$$