Question

Calculate the moment of inertia of the disc having a mass of 1 kg and radius of 1 m.

(a) 1 kgm^2

(b) .5 kgm^2

(c) 2 kgm^2

(d) 3 kgm^2

The question was posed to me in quiz.

This intriguing question comes from Effect of Starting on Power Supply, Motor and Load in chapter Starting of Electric Drives

Answer 1

Correct option is (b) .5 kgm^2

The explanation is: The moment of inertia of the disc can be calculated using the formula I=mr^2×.5. The mass of the disc and diameter is given. I=(1)×.5×(1)^2=.5 kgm^2. It depends upon the orientation of the rotational axis.