# physics

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A catcher stops a 200km/h pitch in his glove, bringing it to rest in 0.15meters. If the force exerted by the catcher is 803N, what is the mass of the ball?

• physics -

v0=200 km/h = 200/3.6 m/s = 55.6 m/s
v1=0
v0^2-v1^2=2aS
S=0.15 m
a=(v0^2-0)/(2S)
=10288 m/s²
F=ma
m=a/F
=10288/803 kg
=0.078 kg.

Unfortunately, baseballs usually weigh around 140 g., so I don't know if something is wrong somewhere. Check my thinking.

• physics -

Pretty silly question. The official mass of a major league baseball is 0.145 kg. No pitcher has ever thrown a baseball 200 km/h. Not even Sandy Koufax.

You can derive a baseballmass from the numbers you were given by equating the kinetic energy of the baseball to the work done against the glove, and solving for m. What you derive may or may not agree with the actual mass of a baseball.

• physics -

MathMate had everything right up to a/F. It should be F/a=m

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