A ball with a mass of 15 kg moving at 4 m/s hits a still ball with a mass of 24 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?

1 Answer
Jan 17, 2016

Speed = 6.25ms^-1
Energy lost = 45J

Explanation:

Momentum is conserved so:

Momentum before = momentum after
15 * 4 = 24 * v
v=60/24=2.5ms^-1

Kinetic energy = 1/2mv^2

KE Before = 1/2*15*4^2=120J

KE After = 1/2*24*2.5^2=12*6.25=75J

Energy lost = 120-75=45J