6.4.B—Describe how the selection of a system determines whether the angular momentum of that system changes

Describe how the selection of a system determines whether the angular momentum of that system changes.

• Angular momentum is conserved in all interactions.
• If the net external torque exerted on a selected object or rigid system is zero, the total angular momentum of that system is constant.
• If the net external torque exerted on a selected object or rigid system is nonzero, angular momentum is transferred between the system and the environment.