A solid cylinder of mass $20 ext{ kg}$ rotates about its axis with angular speed $100 ext{ rad/s}$

Question

A solid cylinder of mass $20	ext{ kg}$ rotates about its axis with angular speed $100	ext{ rad/s}$. If the radius of the cylinder is $0.25	ext{ m}$, what is the magnitude of angular momentum of the cylinder about its axis?

Professor PC Thomas Classes · Answer

The moment of inertia of a solid cylinder about its axis is $I = \frac{MR^2}{2} = \frac{20 	imes (0.25)^2}{2} = 0.625	ext{ kg m}^2$. The angular momentum is $L = I\omega = 0.625 	imes 100 = 62.5	ext{ J s}$.