Venus Williams' tennis racquet gives a 0.057 kg ball a speed of 58 m/s starting from rest, and the racquet stays in contact with the ball for 5.0 ms. What average force does the racquet exert on the ball?

1. The change in momentum is delta p equal to m times (v_f minus v_i), which is (0.057 kg)(58 m/s minus 0 m/s). 2. That multiplication gives a change in momentum of about 3.3 kg m/s. 3. The average net force is F_net equal to delta p divided by delta t, using the 5.0 ms contact time, which is 5.0 times ten to the minus 3 seconds. 4. Dividing gives 3.3 kg m/s divided by 0.0050 s, which is about 660 N. 5. 66,000 N would come from mistakenly treating the contact time as a hundred times shorter than the 5.0 ms actually given, and 6.6 N and 33 N are each off by more than a factor of ten from the correct force. _Source: OpenStax College Physics (CC BY 4.0), Ch 8 "Linear Momentum and Collisions", section 8.2 Impulse_