Solving for the Speed of an 8kg Bullet

[midey]

Homework Statement

An 8 kg bullet is fired into a stationary 9 kg block of wood which is free to move. The bullet is stopped in the wood which has a velocity of 40 cm/s after the impact. What was the speed of the bullet?

Homework Equations

The Attempt at a Solution

 

[matt_crouch]

use the conservation of momentum

 

[jegues]

Well we know from the question that the bullet gets lodged into the wood upon impact. What kind of collision would that be? Elastic or Inelastic? What kind of properties, specifically with conservation of momentum/kinetic energy does that collision contain?

Let me know if you need more help.