State Newton’s second law.
A ball of mass 
hits a wall with a velocity of 
perpendicular to the wall. The ball rebounds perpendicularly from the wall with a speed of 
. The contact time of the ball with the wall is 
.
Calculate, for the ball hitting the wall,
the change in momentum,
the magnitude of the average force.
on a body is equal to the rate of change of momentum 
of the body.
.
.
