Editing Circular motion (section)

{{short description|Object movement along a circular path}}
{{redirect-distinguish|Radial motion|radial velocity|rotational speed}}
{{Classical mechanics|rotational}}

In [[physics]], '''circular motion''' is [[motion|movement]] of an object along the [[circumference]] of a [[circle]] or [[rotation]] along a [[circular arc]]. It can be uniform, with a constant [[rate of rotation]] and constant [[tangential speed]], or non-uniform with a changing rate of rotation. The [[rotation around a fixed axis]] of a three-dimensional body involves the circular motion of its parts. The equations of motion describe the movement of the [[center of mass]] of a body, which remains at a constant distance from the [[axis of rotation]]. In circular motion, the distance between the body and a fixed point on its surface remains the same, i.e., the body is assumed [[rigid body|rigid]]. 

Examples of circular motion include: special satellite orbits around the Earth ([[circular orbit]]s), a [[ceiling fan]]'s blades rotating around a hub, a stone that is tied to a rope and is being swung in circles, a car turning through a curve in a [[race track]], an electron moving perpendicular to a uniform [[magnetic field]], and a [[gear]] turning inside a mechanism.

Since the object's [[velocity vector]] is constantly changing direction, the moving object is undergoing [[acceleration]] by a [[centripetal force]] in the direction of the center of rotation. Without this acceleration, the object would move in a straight line, according to [[Newton's laws of motion]].