Bullet in a Block A(n) 6.1g bullet is shot into a 6,123g wooden block standing on a frictionless surface. The block, with the bullet in it, acquires a velocity of 1.5m/s.

Question

Bullet in a Block

A(n) 6.1g bullet is shot into a 6,123g wooden block standing on a frictionless surface. The block, with the bullet in it, acquires a velocity of 1.5m/s. Calculate the velocity of the bullet before striking the block.

Answer 1

This is a conservation of momentum question

Momentum of system before collision : Bullet, mv. mass is 6.1 g = 0.0061 kg, speed v m/s

momentum, mv = 0.0061v

Block, no momentum.

Total momentum 0.0061 v

After collision

Total mass, 6.1 + 6.123 g = 12.223 g = 0.012223 kg

Momentum = mv = 0.012223 x 1.5

So by conservation of momentum, 0.0061v = 0.012223 x 1.5, solve this for v.

Technically you could have kept the masses in g (as they are both in g) and you would get the same answer.

Mike