Question

The angular momentum of a system remains constant when: A. the total kinetic energy is constant

Answer 1

Answer:

D. when no torque acts on the system

Explanation:

The angular momentum of a system is defined as:

$L=I\omega$

where

I is the moment of inertia of the system

$\omega$ is the angular velocity

This is the equivalent of the linear momentum, p, for rotational motion

$p=mv$

where m is the mass of the system and v is its velocity. From Newton' laws, we know that the change in linear momentum is equal to net force acting on the system, F:

$F=\frac{\Delta p}{\Delta t}$

The analogous relationship for a rotational motion is:

$\tau=\frac{\Delta L}{\Delta t}$

where $\tau$ is the net torque acting on the system. This is the law of conservation of angular momentum, which states that the rate of change of the angular momentum of an object is equal to the net torque on the system: therefore, when no torque acts on the system, the angular momentum is conserved.