Question Detail
Question
What does the equation τ = dL/dt imply about the angular momentum of a body when no net external torque acts on it?
Correct Answer
Option B is the correct answer.
Detailed Explanation
The equation τ = dL/dt is the rotational form of Newton's second law. If the net external torque τ is zero, then dL/dt = 0. The derivative of angular momentum with respect to time being zero means that the angular momentum L does not change; it is constant. This is the law of conservation of angular momentum.
Hint
Consider the translational analogue: if F = 0, then dp/dt = 0, and linear momentum p is constant.