Moment of Inertia
A regulation table tennis ball has a mass of 2.5 g and is 42 mm in diameter.
What is its moment of inertia about an axis that passes through its center?
m: 2.5 g or .0025 kg
d: 42 mm or .042 m
r= .042/2 = .021m
Moment of Inertia for a hollow sphere
I =(2/3) x m x r²
I = (2/3) x 0.0025 x (0.021)2 = .00000074 kg * m2
I = 7.4 x 10-7 kg * m2