A 2200kg car travelling at 30ms collides with another 2200kg car that is at rest. The two bumpers lock and the cars move forward together. What is their final velocity?

Hockey puck A (2kg) travels with a velocity of 40ms to the right when it collides with hockey puck B (1.6kg), which was originally at rest. After the collision, puck A is stationary. Assume no external forces are in play and that the momentum of the pucks are conserved. What is the final velocity of puck B after the collision?

A 12kg ball moving at 37ms strikes a second ball at rest. After the collision the 12kg ball is moving with a velocity of 19ms and the second ball is moving with a velocity of 4ms. What is the mass of the second ball?