Prompt Title: Mech Engg Video Interview.

Stress and strain are concepts used in the study of solid mechanics to describe the deformation of a material under an applied load.

Stress is defined as the internal force per unit area that a material experiences when it is subjected to an external load. It is a tensor quantity and has units of force per unit area (e.g., N/m^2 or Pa). Stress can be expressed in terms of normal stress (perpendicular to the surface) or shear stress (parallel to the surface).

Strain is a measure of the deformation of a material relative to its original size or shape when it is subjected to a load. It is also a tensor quantity and has no units since it is a ratio of lengths or distances. Strain can be expressed in terms of normal strain (stretching or compression) or shear strain (distortion).

The Generalized Hooke's Law is a constitutive equation that relates stress and strain in a linear elastic material. The tensor form of Generalized Hooke's Law is:

σij = Cijklεkl

where σij is the stress tensor, Cijkl is the elasticity tensor (which describes the material properties), and εkl is the strain tensor. This equation relates the components of stress and strain in all directions and accounts for the anisotropy of the material.