A rigid body rotates with an angular momentum L. If its rotational kinetic energy is made four times, its…

A rigid body rotates with an angular momentum L. If its rotational kinetic energy is made four times, its angular momentum will become
  1. $4 \mathrm{~L}$
  2. $16 \mathrm{~L}$
  3. $\sqrt{2} \mathrm{~L}$
  4. $2 \mathrm{~L}$

Solution

Angular momentum, $\begin{aligned} \mathrm{L} & =\sqrt{2 \mathrm{KI}} \\ \mathrm{K}^\prime & =4 \mathrm{~K} \\ \therefore \quad \mathrm{L} & =\sqrt{2 \times 4 \mathrm{KI}}=2 \sqrt{2 \mathrm{KI}}=2 \mathrm{~L} \end{aligned}$

Asked in: MHT CET 2023 (13 May Shift 1)

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