Question

The rotational kinetic energy of a body is $KE$ and its moment of inertia is $I$ The angular momentum is

• A. $KEI$
• B. $2\sqrt{KEI}$
• C. $\sqrt{2KEI}$
• D. $KE/I$

Answer 1

Answer: (C)

$\sqrt{2KEI}$

Answer 2

Rotational, $K E=\frac{1}{2} I \omega^{2} \ldots$ (i) Angular momentum $(L)=I \omega$ or $L^{2}=I^{2} \omega^{2} \ldots$ (ii) $\therefore \frac{K E}{L^{2}}=\frac{\frac{1}{2} I \omega^{2}}{I^{2} \omega^{2}}=\frac{1}{2 I}$ $L^{2}=2 K E I$ $L=\sqrt{2 K E I}$