AP Physics 1: Algebra-Based Flashcards: Conservation of Angular Momentum
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 10 cards to help you master important concepts.
How do you determine the total angular momentum for a system made of multiple rotating parts?
The total angular momentum is calculated by taking the vector sum of the individual angular momenta of all the system's constituent parts about the same axis.
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How do you determine the total angular momentum for a system made of multiple rotating parts?
The total angular momentum is calculated by taking the vector sum of the individual angular momenta of all the system's constituent parts about the same axis.
What is the total angular momentum of a system?
The total angular momentum of a system about a rotational axis is the sum of the angular momenta of the system’s constituent parts about that axis.
A spinning star collapses under its own gravity. Assuming no mass is lost, what happens to its rotational speed?
Because the internal gravitational forces produce no net external torque, the star's angular momentum is conserved; as its radius decreases, its rotational speed must increase.
Under what condition is the angular momentum of a system conserved?
If the net external torque exerted on a selected object or rigid system is zero, the total angular momentum of that system is constant.
Why is 'net external torque' a critical phrase when discussing the conservation of angular momentum?
It is critical because internal torques within a system cancel out and do not change the system's total angular momentum; only a net torque from an external source can cause a change.
What is the principle of conservation of angular momentum?
The principle states that if the net external torque on a system is zero, the total angular momentum of that system remains constant.
An ice skater is spinning with her arms outstretched. If she pulls her arms in, how can her change in speed be described using conservation of angular momentum?
Since there is no net external torque, her angular momentum is conserved; as she pulls her arms in, her rotational inertia decreases, causing her angular speed to increase to keep the total angular momentum constant.
What causes a change in a system's total angular momentum?
A change in a system's total angular momentum is caused by a non-zero net external torque exerted on that system.
In what types of interactions is angular momentum conserved?
Angular momentum is a fundamental quantity that is conserved in all interactions.
How does the selection of a system determine if its angular momentum changes?
The selection of a system defines which torques are external; if the chosen system has zero net external torque, its angular momentum is conserved, but if it has a net external torque, its angular momentum will change.