Question

Calculate the moment of inertia of the circular hollow disk having a mass of 2 kg and an internal radius of 5 m and an external radius of 10 m.

(a) 125 kgm^2

(b) 127 kgm^2

(c) 122 kgm^2

(d) 123 kgm^2

This question was posed to me by my school principal while I was bunking the class.

My query is from Motors Rating and Heating topic in division Rating and Heating of Motors of Electric Drives

Answer 1

Right answer is (a) 125 kgm^2

For explanation: The moment of inertia of the circular hollow disk can be calculated using the formula I=M(R1^2+R2^2)÷2. The mass of circular hollow disk and radius is given. I=(1)×{(5)^2+(10)^2}=125 kgm^2. It depends upon the orientation of the rotational axis.