Question

Calculate the moment of inertia of the sphere having a mass of 8.4 kg and radius of 61 cm.

(a) 3.124 kgm^2

(b) 3.125 kgm^2

(c) 4.545 kgm^2

(d) 5.552 kgm^2

I have been asked this question in an internship interview.

The doubt is from Induction Motors in section Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct choice is (b) 3.125 kgm^2

The best I can explain: The moment of inertia of the egg can be calculated using the formula I=Σmiri^2. The mass of egg and radius is given. I=(8.4)×(.61)^2=3.125 kgm^2. It depends upon the orientation of the rotational axis.