Question

The moment of inertia of a disc about an axis through its centre and perpendicular to its plane is 10 kg.m² . Find its MI about a diameter.

Answer 1

Data : I_z = 10 kg.m²

If the disc lies in the xy plane with its centre at the origin then, according to the theorem of perpendicular axes,

I_x + I_y = I_z

Since, I_x = I_y , 2I_x = I_z

∴ Its MI about a diameter,

I_x = \(\frac{I_z}2\) = \(\frac{10}2\)= 5 kg.m²