A rigid body is an ensemble of particles whose relative distances remain fixed. In any real body subject to forces this condition can never be fully satisfied, since under the action of the forces the body will change its shape, if ever so slightly. However, in some cases, considering the body as rigid and neglecting the changes in its shape under the action of the forces can yield an approximation that is good enough to allow us to simplify the description of its motion considerably. As such, rigid bodies have been widely studied and are important, for example, to understand the motions of a planet such as the Earth as well as gyroscopes and other mechanical systems.
KeywordsAngular Momentum Angular Velocity Reference Frame Rigid Body Inertial Frame
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