Question

A 0.065-kg tennis ball moving to the right with a speed of 15 m/s is struck by a tennis racket, causing it to move to the left with a speed of 15 m/s. if the ball remains in contact with the racquet for 0.020 s, what is the magnitude of the average force exerted on the ball?

Answer 1

Using the formula for impulse, we can solve this problem.
In terms of change in momentum, impulse is:
I = m (v2 - v1)

Or in terms of force and contact time:
I = F t

Equating the two equations:
m (v2 - v1) = F t

Setting the right direction as positive and the left as negative, we can then substitute values with their respective signs:
0.065 (-15 -15) = F (0.020)
F = -97.5 N

The negative sign indicates that the force was directed to the left.