Rotational motion

Article By:

Barger, Vernon D. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin.

Last reviewed:September 2021

DOI:https://doi.org/10.1036/1097-8542.594400

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• Rotational motion, published January 2020:Download PDF Get Adobe Acrobat Reader

The motion of a rigid body which takes place in such a way that all of its particles move in circles about an axis with a common angular velocity; also, the rotation of a particle about a fixed point in space. Rotational motion is illustrated by (1) the fixed speed of rotation of the Earth about its axis (Fig. 1); (2) the varying speed of rotation of the flywheel of a sewing machine; (3) the rotation of a satellite about a planet, in which both the speed of rotation and the distance from the center of rotation may vary; (4) the motion of an ion in a cyclotron, where the angular speed of rotation remains constant, but the radius of the circular motion increases; and (5) the motion of a pendulum, in which case the particles describe harmonic motion along a circular arc. This article's discussion of rotational motion is limited to the circular motion exhibited by the first and second examples. See also: Celestial mechanics; Classical mechanics; Earth rotation and orbital motion; Harmonic motion; Motion; Particle accelerator; Pendulum

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