Question

Assertion : When no external torque acts on a body, its angular velocity remains constant as long as moment of inertia is constant.
Reason : Torque $\tau=0 ; \frac{ dL }{ dt }=0, L =$ constant. $L = I \omega=$ constant

• A. If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
• B. If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
• C. If the Assertion is correct but Reason is incorrect.
• D. If the Assertion is incorrect and Reason is correct.

Answer 1

Answer: (A)

Torque $\tau=\frac{d L}{d t}$
$\therefore \tau=0, L=$ constant.
$I \omega=$ constant
$\therefore \omega$ is constants as long as $I$ is constant.