Question

A soccer ball with a mass of 0.60 kg travels toward a soccer goalie at

a speed of 18 m/s. The goalie catches the ball, bringing it to a stop
in 0.035 s. What is the force exerted by the goalie on the soccer ball?

A 58.0 g incoming tennis ball has a speed of 30 m/s when it is hit by a
racket in the opposite direction and leaves the racket at 40 m/s. What
is the average force exerted by the racket on the ball if contact lasted
for 5.2 ms?

Answer 1

Assuming constant acceleration, the goalie slows the ball from 18 m/s to rest in 0.035 s, so that the acceleration felt by the ball is

`a_(\rm ave) = a = (18(\rm m)/(\rm s)-0)/(0.035\,\mathrm s) \approx \boxed{510(\rm m)/(\mathrm s^2)}`