A tennis ball of mass 57. g bounces off a wall. Right before hitting the wall, the ball is moving to the right and up with vx=+40. m/s and vy=+10. m/s. Right after bouncing off the wall, the ball is moving to the left and up with vx=-35. m/s and vy=+10. m/s.

Question

If the ball is in contact with the wall for 4.5 ms, what is the average force that the wall makes on the ball?

Answer 1

change of momentum normal to the wall
=m(vx1-vx0)=m(-35-40)=-75m kg-m/s
change of momentum parallel to wall
=m(vy1-vy0)=m(10-10) = 0 kg-m/s
Time = 4.5 ms
Average Force
= rate of change of momentum
= -75*0.057/(0.0045) N
= ?