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

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