Conservation of Momentum

1.

A 6 kg chemistry tube, which is at rest on a smooth plane, fragments into two pieces of masses 2 kg and 4 kg after an internal explosion, as shown in the figure. If the 2 kg piece moves due west at a velocity of 10 m/s after the explosion, what is the velocity of the other piece ?

2. A 30 kg child at rest with roller skater throws a 1 kg ball at a velocity of 6 m/s to his friend horizontally?

a) What is the impulse acting on the child?

b) Neglecting the friction on the ground, at what velocity and in which direction does the child move?

3.

A 4 kg mass fragments into two pieces as a result of an internal explosion. If the pieces move as shown in the figure, what is the velocity of the object before the explosion?

4.

A 30 kg child is standing on a 25-kg car which is moving at a velocity of 4 m/s relative to the ground, as shown in the figure. If the child jumps off the car with a velocity of 6 m/s relative to the ground, in the opposite direction to that of the car, what will the final velocity of the car relative to the ground be?

5.

A long wooden beam with a mass of 30 kg is at rest on a smooth surface. A 40 kg child who is initially stationary starts walking on the beam and reaches a velocity of 1.2 m/s relative to the ground in 2 s.

a) What is the velocity of the beam?

b) What is the magnitude of the force applied by the child on the beam?

6.

While a 2 kg object is moving at a velocity of 10 m/s, a 0.1 kg bullet is fired into the object at a velocity of 100 m/s and leaves it at a velocity of 80 m/s, as shown in the figure. What is the final velocity of the object? (Neglect any friction and energy transferred into heat.)

7.

A hunter whose mass is 75 kg fires a 5 kg rifle. A bullet with a mass of 40 g leaves the rifle with a velocity of 500 m/s. Find the recoil velocity of the rifle for the conditions below

a) if the hunter holds the rifle loosely.

b) if the hunter holds the rifle firmly and presses it against his shoulder.

8.

A spring is placed between two objects of masses 4 kg and 8 kg on a frictionless plane. It is totally compressed by the objects, which are then tied together with a piece of cord, as shown in the figure. After the cord is cut, if the 4 kg object moves towards the left with a velocity of 5 m/s

a) what is the velocity of the 8 kg object?

b) what are the kinetic energies of the objects?

c) how much energy is initially stored in the spring?

Date: 2015-01-29; view: 1238