Problem: In softball, the pitcher throws with the arm fully extended (straight at the elbow). In a fast pitch the ball leaves the hand with a speed of 139 km/h.Find the rotational kinetic energy of the pitcher's arm given its moment of inertia is 0.720 kg⋅m2 and the ball leaves the hand at a distance of 0.600 m from the pivot at the shoulder (the ball is 0.156 kg).

FREE Expert Solution

Rotational kinetic energy:

K=12Iω2 where I is the moment of inertia and ω is the angular velocity.

Moment of inertial of a point mass:

I=mr2

Relationship between linear velocity and angular velocity.

ω=vr

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Problem Details

In softball, the pitcher throws with the arm fully extended (straight at the elbow). In a fast pitch the ball leaves the hand with a speed of 139 km/h.

Find the rotational kinetic energy of the pitcher's arm given its moment of inertia is 0.720 kg⋅mand the ball leaves the hand at a distance of 0.600 m from the pivot at the shoulder (the ball is 0.156 kg).

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