Rotational Inertia Formula

Rotational Inertia

The rotational inertia is a property of any object which rotates. In the case of linear motion, the rotational inertia is known as an analog of mass. The moment of inertia depends not only on the mass and shape of the object but also on the axis of rotation. The rotational inertia is various with the object depending on the rotational axis.

The formula for rotational inertia is

I = mr2


I = rotational inertia

m = mass of the object

r = radius of the circular path

Solved Example

Example 1

Determine the moment of inertia of the object with mass 20kg and rotating around the radius 8m?



m = 20kg

r = 8m

The formula Rotational inertia is

I = mr2

I = 20 × 82

I = 1280 kgm2

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