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