A ball with a mass of # 6 kg# is rolling at #7 m/s# and elastically collides with a resting ball with a mass of # 8 kg#. What are the post-collision velocities of the balls?

1 Answer
Feb 14, 2016

Answer:

#v_1^'=-7 m/s#
#v_2^'=0#

Explanation:

#"total momentums before event=total momentum after event"#
#vec P_(1b)+ vec P_(2b)=vec P_(1a)+ vec P_(2a)#
#6*7+0=6*v_1^'+8*v_2^'#
#42=6*v_1^'+8*v_2^' " (1)"#
#v_1+v_1^'=v_2+v_2^'#
#7+v_1^'=0+v_2^' " (2)"#
#v_1^'=v_2^'-7#
#42=6*(v_2^'-7)+8.v_2^'#
#42=6*v_2^'-42+8*v_2^'#
#14*v_2^'=0#
#v_2^'=0#
#v_1^'=0-7#
#v_1^'=-7 m/s#