A ball with a mass of # 5 kg# is rolling at #6 m/s# and elastically collides with a resting ball with a mass of #9 kg#. What are the post-collision velocities of the balls?

1 Answer
Feb 22, 2016

Answer:

#v_1=-12/7 m/s#
#v_2=30/7m/s#

Explanation:

#5*6+0=5*v_1+9*v_2" Conversation of momentum"#
#30=5*v_1+9*v_2 " (1)"#
#6+v_1=0+v_2#
#"'the sum of velocities of objects before and after collision is equal'" #
#v_2=6+v_1" (2)"#
#30=5*v_1+9*(6+v_1)#
#30=5*v_1+54+9*v_1#
#30-54=14*v_1#
#-24=14*v_1#
#v_1=-24/14#
#v_1=-12/7 m/s#
#"use (2)"#
#v_2=6-12/7#
#v_2=30/7m/s#