A ball with a mass of #9 kg# moving at #14 m/s# hits a still ball with a mass of #18 kg#. If the first ball stops moving, how fast is the second ball moving?
If the second ball is in rest before collision then after collision velocity of the second ball is 7m/s.
by conservation of linear momentum
9 x 14 + 18 x 0 = 9 x 0 + 18 x