A baseball pitcher loosens up his pitching arm.He tosses a 0.20-kg ball using only the rotation of his forearm,0.32 m in length,to accelerate the ball.What is the moment of inertia of the ball alone as it moves in a circular arc with a radius of 0.32 m? A) 7.7 × 10−² kg·m² B) 1.9 × 10−² kg·m² C) 3.8 × 10−² kg·m² D) 1.2 × 10−² kg·m² E) 6.2 × 10−² kg·m²

Question

Quizplus · Accepted Answer

The moment of inertia of a point mass is given by:
I=mr^2
where:
m = mass of the ball
r = radius of the circular arc

We are given the mass of the ball as 0.20 kg and the radius of the circular arc as 0.32 m. Substituting these values into the equation above, we get:

I = (0.20 kg) x (0.32 m)^2 = 0.02048 kg·m^2

Rounding this off to two significant figures, we get:
I = 1.9 x 10^-2 kg·m^2

Thus, the best choice is B.

A Baseball Pitcher Loosens Up His Pitching Arm