A ball with a mass of #9 kg# moving at #3 m/s# hits a still ball with a mass of #21 kg#. If the first ball stops moving, how fast is the second ball moving? How much kinetic energy was lost as heat in the collision?
Momentum of the system before collision:
now kinetic energy before
energy lost to collision = 40.5-17.36 = 23.14 J