A metallic ring of mass 1 kg has moment of inertia 1 kg m² when rotating about one of its diameters. It is molten and remoulded into a thin uniform disc of the same radius. How much will its moment of inertia be, when rotated about its own
axis.

The moment of inertia of disc about own axis is 1 kg-m².

Explanation:

Given that,

Mass of ring m= 1 kg

Moment of inertia of ring at diameter

The radius of metallic ring and uniform disc both are equal.

So,

We need to calculate the value of radius of ring and disc

Using theorem of perpendicular axes

Put the value into the formula

Put the value of moment of inertia

Put the value of M

So,

We need to calculate the moment of inertia of disc about own axis

Using formula of moment of inertia

Put the value into the formula

Hence, The moment of inertia of disc about own axis is 1 kg-m².

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