Which statement best describes angular momentum for a rotating body?

Which statement best describes angular momentum for a rotating body?

• A. Angular momentum equals angular velocity multiplied by moment of inertia.
• B. Angular momentum is not conserved in any system.
• C. Moment of inertia equals speed of rotation.
• D. Angular momentum equals angular velocity multiplied by acceleration.

Answer: (D)

Angular momentum for a rotating body depends on how mass is distributed relative to the axis of rotation and how fast the body spins. The correct description is that angular momentum equals the moment of inertia multiplied by the angular velocity. The moment of inertia captures the mass distribution, while the angular velocity tells how quickly the body rotates; together they give the rotational momentum with the proper units and physical meaning. This quantity can be conserved in a system when there is no external torque, which explains why devices or athletes can change spin rate by redistributing mass yet keep the total angular momentum constant. The other ideas aren’t accurate: the moment of inertia is not the same thing as speed of rotation, and angular momentum is not equal to angular velocity times angular acceleration—the latter would have incorrect units and does not describe L, which evolves according to dL/dt = torque.

Angular momentum for a rotating body depends on how mass is distributed relative to the axis of rotation and how fast the body spins. The correct description is that angular momentum equals the moment of inertia multiplied by the angular velocity. The moment of inertia captures the mass distribution, while the angular velocity tells how quickly the body rotates; together they give the rotational momentum with the proper units and physical meaning. This quantity can be conserved in a system when there is no external torque, which explains why devices or athletes can change spin rate by redistributing mass yet keep the total angular momentum constant. The other ideas aren’t accurate: the moment of inertia is not the same thing as speed of rotation, and angular momentum is not equal to angular velocity times angular acceleration—the latter would have incorrect units and does not describe L, which evolves according to dL/dt = torque.