A 3.0-kg ball with an initial velocity of (4 î + 3 ĵ )m/s collides with a wall and rebounds with a velocity of (-4 î + 3 ĵ )m/s.What is the impulse exerted on the ball by the wall?
A)+24 î N's
B)-24 î N's
C)+18 ĵ N'S
D)-+18 ĵ N'S
E)+8.0 î N's

Question

Quizplus · Accepted Answer

The impulse-momentum theorem states that the impulse exerted on an object is equal to the change in momentum of the object. In this case, the change in momentum of the ball is:

Δp = mΔv

where m is the mass of the ball and Δv is the change in velocity of the ball.

Δv = (-4 î + 3 ĵ )m/s - (4 î + 3 ĵ )m/s 
Δv = -8 î m/s

Δp = (3.0 kg)(-8 î m/s) 
Δp = -24 î N's

Since the ball rebounds in the opposite direction, the impulse exerted on the ball by the wall must also be in the opposite direction. Therefore, the correct answer is B, -24 î N's.

A 30-Kg Ball with an Initial Velocity of (4 Î