Question

Newton’s second law of rotational motion of a system of particles having angular momentum \( L \) is given by

• A. \( \frac{dp}{dt} = \tau_{\text{ext}} \)
• B. \( \frac{dL}{dt} = \tau_{\text{int}} \)
• C. \( \frac{dL}{dt} = \tau_{\text{ext}} \)
• D. \( \frac{dL}{dt} = \tau_{\text{int}} + \tau_{\text{ext}} \)

Hint:

Only external torques can change the angular momentum of a system.

Answer 1

The Correct Option is C

The rotational analogue of Newton's second law is: \[ \frac{dL}{dt} = \tau_{\text{ext}} \] This holds when internal torques cancel out (equal and opposite pairs), and only external torque contributes to change in angular momentum.