A ball with a mass of 7 kg moving at 1 m/s hits a still ball with a mass of 10 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
Nov 2, 2016

By momentum conservation ,

P_i=P_f------[where P= momentum= mass xx velocity]

Let the velocity of ball with mass 10 kg be 'v'.

7 xx 1+10 xx 0 = 7 xx 0 + 10 xx v

7=10v

v=7/10

v= 0.7m/s

Loss in kinetic energy = KE_i - KE_f#

Loss in kinetic energy = 1/2 xx 7xx 1- 1/2 xx 10 xx 0.7xx0.7

Loss in kinetic energy = 7/2 - 49/20

Loss in kinetic energy = 21/20 Joule