500
A 2 kg ball is rolling to the right with a velocity of 5 m/s. A 4 kg ball is also rolling to the right, with a velocity of 2 m/s. If the 2 kg ball catches up and collides with the 4 kg ball, giving the 4 kg ball a final velocity of 3 m/s, what is the final velocity of the 2 kg ball?
3 m/s