Rigid body

Summary

A rigid body is an idealised solid body in which the distance between any two of its points never changes. Its position at each time is given by a rotation and a translation, that is, by an element of the Euclidean group. This needs six numbers in space and three in the plane. The model ignores deformation, and it is accurate when deformations are small compared with the motion. Rigid bodies are the basic objects of rigid body kinematics and dynamics.