ABSTRACT
This chapter deals with the description of elastic bodies. Elasticity is a phenomenon wherein a body responds to external forces not (only) by accelerating (as a rigid body would have done) but by deforming-changing its shape or size or both. Elasticity, unlike plasticity, is reversible. Elastic objects that change their shape or size in response to external forces (or ‘stresses’) revert back to their original state upon removal of those forces. Plastic objects on the other hand do not. A fluid is an elastic material that flows. This means that the material will suffer acceleration whenever anisotropic stresses are applied. We first study elasticity theory followed by fluid mechanics. These descriptions are meant to be simple introductions only. The reader is referred to the bibliography for more specialized treatises.
