Question

A solid circular disc of mass m and radius r is lolling on a horizontal plane with angular velocity ω figure. What will be angular momentum of the disc about origin O?

Answer 1

Moment of inertia of the disc about the axis OX. According to the theorem of parallel axes:

\(I = I_{cm} + mr^2 = \frac{1}{2}mr^2 + mr^2\)

 = \(\frac{3}{2}\ mr^2\)

∴ Angular momentum of the disc about the origin:

\(L = I\omega = \frac{3}{2}\ mr^2\omega\)