Question

A ring of mass $10kg$ and diameter $0.4m$ is rotating about its geometrical axis at $1200$ rotations/minute. Its moment of inertia and angular momentum will be respectively:

• A. $0.4kg{m}^2$ and $50.28Joule/sec$
• B. $50.28kg{m}^2$ and $0.4Joule/sec$
• C. $0.4Joule/sec$ and $50.28kg{m}^2$
• D. $0.4kg{m}^2$ and $0kg{m}^2$

Answer 1

The correct option is A $0.4kg{m}^2$ and $50.28Joule/sec$

Moment of Inertia, $I=M{r}^2=10\times {0.2}^2=0.4kg{m}^2$
Angular Momentum, $L=I\times \omega =0.4\times \left(\frac{1200\times 2\pi }{60}\right)=50.28Joule/sec$