Physics Homework Help?

Question

A tennis ball of mass m = 0.065 kg and speed v = 25 m/s strikes a wall at a 45∘ angle and rebounds with the same speed at 45∘.

 

A.) What is the magnitude of the impulse given to the ball?

 

B.) What is the direction of the impulse given to the ball?

What is the direction of the impulse given to the ball?

	upward
	downward
	to the left
	to the right

 

Answer 1

(a)

Step 1:

The mass of a tennis ball is .

The velocity of the ball is .

The ball strikes a wall with an angle is .

The initial momentum along the -axis: .

The final momentum along the -axis: .

The impulse along the -axis: .

.

The initial momentum along the -axis: .

The final momentum along the -axis: .

The impulse along the -axis: .

Step 2:

The impulse is .

Substitute and .

.

The magnitude of the impulse is .

Solution:

The magnitude of the impulse is .

Answer 2

(b)

The impulse is .

Minus sign here indicates that impulse is in opposite direction to the initial velocity.

Since the ball strikes the wall with an angle of upwards, the ball rebounds in opposite direction.

Therefore, the direction of the impulse given to the ball is downwards.

The option (b) is the correct choice.