By Kate Allaway

Andy Pettitte has pitched for the Yankees for a total of 12
years and in that time has been an all-star 3 times and has won numerous
awards. He is also major league baseball’s all time wins leader in the post
season with 19 post season wins. Pettitte throws a four-seam fastball, a cutter, a curveball, a sinker, a changeup, and
a slider.

Here
I will look at his fastball and determine the force it exerts on a baseball
bat.

His fastballs typically have a speed of 91 mph, or 41.7 m/s.

V

_{o }= 0 m/s
V

_{f }= 41.7 m/s
Distance from pitcher’s mound to home plate = 18.39 m

V

_{f }^{2}= v_{o}^{2}+ 2a(Δx)
(41.7 m/s)

^{2}= (0 m/s)^{2}+ 2a(18.39 m)
a = 47.3 m/s

^{2}
m

_{baseball}= 145g = 0.145 kg
F

_{exerted by baseball}=(0.145kg)(47.3 m/s^{2})=6.9 N
Would this force break a (stationary) bat?

Ultimate (shear) strength of the wood of a bat=5x10

^{6}N/m^{2}
Estimate that about a circle with a radius of 1 cm (A= 3x10

^{-4}m^{2}) of the ball comes in contact with the bat
Stress = (6.9 N/3x10

^{-4}m^{2}) = 23,000 N/m^{2}
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