Centripetal Force

Summary

Circular motion in which the speed is constant is called uniform circular motion.
A centripetal acceleration …
- occurs whenever a moving object changes direction
- does not change the speed of an object
- acts at right angles to the velocity at any instant
- is directed toward the center of a circle
A centripetal force …
- is the force that makes a moving object change direction
- is not a particular force, but the name given to the net force responsible for circular motion
- acts at right angles to the velocity at any instant
- is directed toward the center of a circle
Directions in circular motion:
- Velocity is tangential (lies on a tangent to the path).
- Centripetal acceleration and centripetal force are radial (point toward the center of a circle).
- Centripetal acceleration and velocity are always perpendicular.
- Centripetal force and centripetal acceleration are always parallel.

Magnitudes in circular motion

A centrifugal force …
- is experienced by an object in a rotating reference frame
- is a fictitious or apparent force
- ceases to exist when an object stops moving in a circle
- feels as though it is directed away from the center of a circle