# Physics

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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.

• Physics -

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)
Mball*40^2

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