Question

A disc of mass M and radius R is rolling with angular speed $\omega$ on a horizontal plane as shown. The magnitude of angular momentum of the disc about the origin O is

• A. $\left(\frac{1}{2}\right)M{R}_2\omega$
• B. $M{R}^2\omega$
• C. $\left(\frac{3}{2}\right)M{R}^2\omega$
• D. $2M{R}^2\omega$

Answer 1

The correct option is C

$\left(\frac{3}{2}\right)M{R}^2\omega$

$L=m\omega R^2+I\omega =m\omega R^2+\frac{m{R}^2}{2}\omega =\frac{3m{R}^2}{2}\omega$