Question

A 2 x 10^-3 kg bullet (m) is shot into a 5 kg block (M) of wood which is fixed to a friction less horizontal surface. The bullet hits the block at v = 500m/s

1) Calculate the magnitude of the momentum of the bullet as it hits the block.

2) The bullet embeds itself in the block. How much work is done by the resistive force due to the block in bringing the bullet to rest?

3) The average force exerted by the block is 2500 N. How far does the bullet travel into the block?

4) From the moment the bullet hits the block, how long does it take for it to come to rest?

5) Before the collision the bullet has momentum. After the collision the bullet and the block are at rest with zero momentum. Explain why momentum appears not to be conserved.

6) Instead of being fixed to the surface imagine the block is free to move as the bullet strikes it. In this case evaluate the speed of the block ( with the bullet embedded) immediately after the collision. When appropriate you may ignore the mass of the bullet with respect to that of the block.

7) How much kinetic energy is gained or lost in this collision? Is the collision elastic or inelastic?

Answer 1