Q. A ring of radius $0.5\ m$ and mass $10\ kg$ is rotating about its diameter with angular velocity of $20\ rad/s$. Its kinetic energy is
A) $10\ J$
B) $100\ J$
C) $500\ J$
D) $250\ J$
Explanation
(d) Rotational kinetic energy $= \frac{1}{2}I\omega^{2} = \frac{1}{2}\left( \frac{1}{2}MR^{2} \right) \times \omega^{2}$
$= \frac{1}{2}\left( \frac{1}{2} \times 10 \times (0.5)^{2} \right) \times (20)^{2} = 250\ J$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.