# Linear momentum, bullet's energy, and billiard ball rebound

For the following problems, the answers are given. Show the workings to arrive at the correct answers.

1. If a 60 kg woman is riding in a car travelling at 90km/h, what is her linear momentum relative to

(a) The ground (b) the car?

Answer: (a) 1.5 x 10^3 kg.m/s (b) zero

2. A 5-g bullet with a speed of 200m/s is fired horizontally into a 0.75 kg wooden block at rest on a table. If the block containing the bullet slides a distance of 0.20m before coming to rest, (a) what is the coefficient of kinetic friction between the block and the table? (b) what fraction of the bullet's energy is dissipated in the collision?

Answer: (a) 0.45 (b) 99%

3. A 0.20 kg billiard ball travelling at a speed of 15m/s strikes the side rail of the pool table at an angle of 60 degree. If the ball rebounds at same speed and angle, what is the change in its momentum?

Answer: (a) ∆p = (-3.0 kg.m/s) ỳ

4. A pool player imparts an impulse of 3.2 N.s to a stationary 0.25 kg cue ball with a cue stick. What is the speed of the ball just after the impact?

Answer: 13m/s

5. An incoming 0.14 kg baseball has a speed of 45 m/s. The batter hits the ball, giving it a speed of 60 m/s. If the contact time is 0.040 s, what is the average force of the bat on the ball?

Answer: 3.7 x 10^2 N

https://brainmass.com/physics/work/linear-momentum-bullets-energy-billiard-ball-rebound-279672

#### Solution Preview

Clear work out is attached with the word document.

1. If a 60 kg woman is riding in a car travelling at 90km/h, what is her linear momentum relative to

(a) The ground (b) the car?

Answer: (a) 1.5 x 10^3 kg.m/s (b) zero

a) As she is moving relative to ground,

her momentum = mass * speed = 60 * 90(5/18) = 1.5 x 10^3 Kg.m/s

b) But as she will be at rest relative to the car. So her momentum is 'zero' relative to car.

2. A 5-g bullet with a speed of 200m/s is fired horizontally into a 0.75 kg wooden block at rest on a table. If the block containing the bullet slides a distance of 0.20m before coming to rest, (a) what is the ...

#### Solution Summary

Linear momentum, bullet's energy and the billiard ball rebound is examined.