In physics, a rigid body is an idealization of a solid body of finite size in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it. Even though such an object cannot physically exist due to relativity, objects can normally be assumed to be perfectly rigid if they are not moving near the speed of light.
In classical mechanics a rigid body is usually considered as a continuous mass distribution, while in quantum mechanics a rigid body is usually thought of as a collection of point masses. For instance, in quantum mechanics molecules (consisting of the point masses: electrons and nuclei) are often seen as rigid bodies (see classification of molecules as rigid rotors).
Read more about Rigid Body: Kinetics, Geometry, Configuration Space
Famous quotes containing the words rigid and/or body:
“The essence of statesmanship is not a rigid adherence to the past, but a prudent and probing concern for the future.”
—Hubert H. Humphrey (1911–1978)
“The elephant, not only the largest but the most intelligent of animals, provides us with an excellent example. It is faithful and tenderly loving to the female of its choice, mating only every third year and then for no more than five days, and so secretly as never to be seen, until, on the sixth day, it appears and goes at once to wash its whole body in the river, unwilling to return to the herd until thus purified. Such good and modest habits are an example to husband and wife.”
—St. Francis De Sales (1567–1622)