A 13g bullet traveling at 330m/s penetrates a 2 kg block of wood and emerges going 270m/s. if the block is stationary on a frictionless surface when hit, how fast does it move after the bullet emerges?

Use the principle of they conservation of momentum to solve this:


m_1v_{1i} +m_2v_{2i}= m_1v_{1f} + m_2v_{2f}


You have values for both masses, the initial velocities of both, and the final velocity of one - so now you can solve for the final velocity of the other.