Comparison of Angular Momenta – Rankers Physics

Angular Momentum and Conservation of Angular Momentum: Practice Problem & Solution

Two rotating bodies $A$ and $B$ of masses $m$ and $2m$ with moments of inertia $I_A$ and $I_B$ ($I_B > I_A$) have equal kinetic energy of rotation. If $L_A$ and $L_B$ be their angular momenta respectively, then: (2016-II)
$L_B > L_A$
$L_A > L_B$
$L_A = \frac{L_B}{2}$
$L_A = 2L_B$

Solution Explained:

To solve this problem, we apply the core principles of Angular Momentum and Conservation of Angular Momentum. Understanding the underlying formula is key to arriving at the correct answer below:

Rotational kinetic energy is related to angular momentum by the formula $K = \frac{L^2}{2I}$, which yields $L = \sqrt{2KI}$. Since $K$ is the same for both bodies and it is given that $I_B > I_A$, it directly follows that $L_B > L_A$.

Leave a Reply

Your email address will not be published. Required fields are marked *