posted by Nora .
Assume a perfectly elastic collision between a 916g bat and a 145g baseball. Initially, the ball was moving at 32 m/s toward the ball and afterward it's heading away at 40 m/s.
Find bat's speed before and after collision.
The change in momentum of the ball equals that of the bat.
Vbat1 - Vbat2 = (0.145/0.916)*(40 + 32)
= 11.40 m/s
The bat slows down after hitting the ball.
Now use conservation of energy to solve for the bat's initial velocity, Mbat1.
(1/2)Mbat*Vbat1^2 + (1/2)Mball*34^2
= (1/2)Mbat*(Vbat1-11.40)^2 + (1/2)