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:
“Success makes men rigid and they tend to exalt stability over all the other virtues; tired of the effort of willing they become fanatics about conservatism.”
—Walter Lippmann (1889–1974)
“These was all nice pictures, I reckon, but I didn’t somehow seem to take to them, because if ever I was down a little, they always give me the fan-tods. Everybody was sorry she died, because she had laid out a lot more of these pictures to do, and a body could see by what she had done what they had lost. But I reckoned, that with her disposition, she was having a better time in the graveyard.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)