Q. In the absence of external torque for a body revolving about any axis, the quantity that remains constant is
A) Kinetic energy
B) Potential energy
C) Linear momentum
D) Angular momentum
Explanation
(d) In the absence of external torque for a body revolving about any axis, the angular momentum remains constant. This is known as law of conservation of angular momentum, $\overrightarrow{\tau} = \frac{d\overrightarrow{L}}{dt}$
As $\overrightarrow{\tau} = 0\ \therefore\frac{d\overrightarrow{L}}{dt} = 0$ or $\overrightarrow{L} =$ constant
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.