Q. Two bodies of moment of inertia $I_{1}$ and $I_{2}$ $(I_{1} > I_{2})$ have equal angular momenta. If $E_{1},E_{2}$ are their kinetic energies of rotation, then

A) $E_{1} > E_{2}$
B) $E_{1} = E_{2}$
C) $E_{1} < E_{2}$
D) Cannot be said
Explanation

(c) $I_{1}\omega_{1} = I_{2}\omega_{2}\ \ \ \therefore\frac{\omega_{1}}{\omega_{2}} = \frac{I_{2}}{I_{1}}$
Now, $\frac{E_{1}}{E_{2}} = \frac{\frac{1}{2}I_{1}\omega_{1}^{2}}{\frac{1}{2}I_{2}\omega_{2}^{2}} = \frac{I_{1}}{I_{2}} \times \left( \frac{I_{2}}{I_{1}} \right)^{2} = \frac{I_{2}}{I_{1}}$
As $I_{1} > I_{2}\ \therefore E_{1} < E_{2}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.