Question

The angular momentum of a rotating body is 'L'. When the frequency of rotating body is tripled and its kinetic energy is made one-third, the new angular momentum becomes

• A. \(9L\)
• B. \(6L\)
• C. \(\frac{L}{3}\)
• D. \(\frac{L}{9}\)

Hint:

Use K = (1/2) L w and remember that the moment of inertia must change.

Answer 1

The Correct Option is D

Step 1: Ratio method:
$\frac{K'}{K} = \frac{L'\omega'}{L\omega}$, so $\frac13 = \frac{L'}{L} \times 3$.

Step 2: Solve:
$\frac{L'}{L} = \frac19$, so $L' = \frac L9$.

Final Answer:
$L' = \frac{L}{9}$, option (D). \[ \boxed{\frac{L}{9}} \]