# Rigid Body

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).

### Other articles related to "rigid body, body, rigid":

Coot (program) - Features - Model Building Tools
... Rigid body fit zone - optimize the fit of a rigid body to the electron density ... Rotate/translate zone - manually position a rigid body ...
Couple (mechanics) - Forces and Couples
... A force F applied to a rigid body at a distance d from the center of mass has the same effect as the same force applied directly to the center of mass and a couple Cℓ = Fd ... The couple produces an angular acceleration of the rigid body at right angles to the plane of the couple ... The force at the center of mass accelerates the body in the direction of the force without change in orientation ...
Spatial Acceleration
... In physics the study of rigid body motion provides for several ways of defining the acceleration state of a rigid body ... of acceleration entails following a single particle/point along the rigid body and observing its changes of velocity ...
Constraint Algorithm - Mathematical Background
... Such an approach is used, for example, in describing the motion of a rigid body the position and orientation of a rigid body can be described by six independent, unconstrained coordinates, rather than describing the ... spring forces that enforce the distances among mass points within a "rigid" body ...
Rigid Body - Configuration Space
... The configuration space of a rigid body with one point fixed (i.e ... a body with zero translational motion) is given by the underlying manifold of the rotation group SO(3) ... (with non-zero translational motion) rigid body is E+(3), the subgroup of direct isometries of the Euclidean group in three dimensions (combinations of translations and rotations) ...

### Famous quotes containing the words body and/or rigid:

Summer, this is our flesh,
The body you let mature;
If now while the body is fresh
You take it, shall we give
The heart....
Allen Tate (1899–1979)

The loosening, for some people, of rigid role definitions for men and women has shown that dads can be great at calming babies—if they take the time and make the effort to learn how. It’s that time and effort that not only teaches the dad how to calm the babies, but also turns him into a parent, just as the time and effort the mother puts into the babies turns her into a parent.
Pamela Patrick Novotny (20th century)