Question

1. A baseball (mass 0.145 kg) is at rest in a mesh net above the ground. A 0.023 kg marshmallow is thrown at the baseball from directly below, and attaches itself to the ball, without hitting the net, while traveling at a speed of 4.30 m/s. How high above its starting position does the baseball-marshmallow combination rise?
2. A 3.30-kg rifle shoots a 13.0-g bullet at 280 m/s. With what speed does the rifle recoil?

Answer 1

Given the mass of the gun, M = 3.3 kg,
mass of the bullet, m = 0.013kg
Speed of the bullet, v = 280 m/s.
2.

Let the velocity of recoil of the gun = V
Using conservation of momentum, we get
Momentum after = momentum before
MV – mv = 0 (as initial momentum was zero)
or, MV = mv
or, 3.3*V = 280*0.013
or, V = 1.10 m/s ...Answer.

Hope this helps!