Conservation of angular momentum

Definition

Conservation of angular momentum is the principle that the total angular momentum of a closed system remains constant if no external torque acts on it. This principle is crucial in explaining the rotational behaviors of celestial bodies.

5 Must Know Facts For Your Next Test

1. Angular momentum depends on the object's mass, velocity, and distance from the axis of rotation.
2. In a two-body orbit, if one object moves closer to the other, its speed increases to conserve angular momentum.
3. The conservation of angular momentum explains why planets maintain stable orbits around stars.
4. This principle helps describe why spinning ice skaters spin faster when they pull their arms in closer to their bodies.
5. It is a fundamental concept derived from Newton's laws of motion and plays a critical role in understanding astronomical phenomena.

Review Questions

• How does the conservation of angular momentum affect an object's rotational speed when its radius changes?
• Why is conservation of angular momentum important for planetary orbits?
• Provide an example where conservation of angular momentum can be observed in everyday life.

Related terms

Torque: A measure of how much a force acting on an object causes that object to rotate, typically measured in Newton-meters (Nm).

Kepler's Second Law: States that a line segment joining a planet and the sun sweeps out equal areas during equal intervals of time, which is related to angular momentum conservation.

Newton's Third Law: States that for every action, there is an equal and opposite reaction; this law underpins the exchange of forces between interacting bodies in orbit.