Undeformable Solid Mechanics

This section deals with the mechanics of the undeformable solid. Whereas the entire course so far has been concerned with material points, we go beyond this model by considering any mass distribution that is totally rigid, i.e., undeformable. From the point of view of the art of modeling a physical system, we learn here how things get complicated when we refine a model. For most students, this is the chapter that brings them face to face for the first time with a so-called tensorial physical property: angular momentum and angular velocity are linked by a linear relationship, but angular momentum and angular velocity are not, in general, collinear vectors. This has important implications for dynamics. Kinematics and certain aspects of dynamics show that, in physics, it is often necessary to understand the structure of mathematical definitions of physical quantities before being able to use them to good effect.