Moment of Inertia

Q1

What is meant by moment of inertia?

The moment of inertia is defined as the quantity expressed by the body resisting angular acceleration, which is the sum of the product of the mass of every particle with its square of the distance from the axis of rotation.

Q2

Does the moment of inertia of a rigid body change with the speed of rotation?

The moment of inertia of a rigid body depends only on the distribution of mass of the body about the axis of rotation and is independent of the speed of rotation. Hence, the moment of inertia of a rigid body does not change with the speed of rotation.

Q3

A disc is recast into a hollow and thin cylinder of the same radius. Which one will have a larger moment of inertia?

The moment of inertia of a hollow cylinder will be larger than the moment of inertia of the disc because most of its mass is located away from the axis of rotation as compared to that of the disc.

Q4

Is the moment of inertia a scalar or vector quantity?

The moment of inertia is a scalar quantity.

Q5

What is the moment of inertia of a solid sphere about its sphere?

I = (⅖)MR²