Two .2kg billiard balls roll toward each other and collide head-on. Initially, ball (1) has a velocity of 0.5 m/s to the right. Ball (2) has an initial velocity of 0.7 m/s to the left. The collision is elastic and ball (2) rebounds with a velocity of 0.4 m/s to the right. What is the velocity of ball (1) after the collision?

Question

anonymous · Answer

Conservation of momentum

m1 v1 + m2 v2 = m1 v1' + m2 v'

(0.2)(0.5) + (0.2)(-0.7) = (0.2) v1' + (0.2)(0.4)

one equation, one unknown, solve for v1'