Question

The law of conservation of angular momentum is obtained from Newton's II law in rotational motion when:

• A. External torque is maximum
• B. External torque is minimum
• C. External torque is zero
• D. External torque is constant

Answer 1

The correct option is C External torque is zero

Newton's 2nd law says that External Force is directly proportional to the rate of change of momentum. Similarly, external torque is directly proportional to the rate of change of angular momentum. So if angular momentum is conserved i.e., the rate of change of angular momentum is zero then external torque is zero.