Question

Calculate the moment of inertia of the tennis ball having a mass of 7 kg and diameter of 152 cm.

(a) 3.55 kgm^2

(b) 4.47 kgm^2

(c) 2.66 kgm^2

(d) 1.41 kgm^2

I have been asked this question during an interview.

The query is from Induction Motors topic in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Right option is (c) 2.66 kgm^2

For explanation: The moment of inertia of the tennis ball can be calculated using the formula I=mr^2×.5. The mass of the ball and diameter is given. I=(7)×.5×(.76)^2=2.66 kgm^2. It depends upon the orientation of the rotational axis.