Q. A body is rotating with angular velocity 30 ${rads}^{- 1}$. If its kinetic energy is 360 J, then its moment of inertia is
A) 0.8 ${kgm}^{2}$
B) ${0.4\ kgm}^{2}$
C) $1\ {kgm}^{2}$
D) 1.2 ${kgm}^{2}$
Explanation
(a) Rotational kinetic energy $K_{R} = \frac{1}{2}I\omega^{2}$
$\therefore$ Its moment of inertia $= \frac{2K_{R}}{\omega^{2}}$
$= 2 \times \frac{360}{(30)^{2}}$
$= 0.8\ kg - m^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.