Assume that a 15-kg ball moving at 8 m/s strikes a wall perpendicularly and rebounds elastically at the same speed. what is the amount of impulse given to the wall?

Mass of the ball is m = 15 kg
Velocity of the ball is v = 8 m/s

The momentum of the ball is
P = mv = (15 kg)*(8 m/s) = 120 (kg-m)/s

Because the ball rebounds elastically, its rebound velocity is 8 m/s in the opposite direction.
The change in momentum of the ball is
2P = 240 (kg-m)/s.

The impulse on the wall is equivalent to the change in the momentum of the ball, so it is 240 (kg-m)/s

 240 (kg-m)/s