Stress and strain

A tensile force is a force that tends to stretch or elongate an object, while a compressive force is a force that tends to compress or shorten an object. Both forces are types of mechanical stress.

Load refers to the force applied to an object. Extension refers to the increase in length of an object due to the applied load. Load is directly proportional to extension within the limit of proportionality.

Hooke's Law states that the extension (or compression) of a spring is directly proportional to the force applied to it, provided the limit of proportionality is not exceeded. Mathematically, F = kx, where F is force, k is the spring constant, and x is the extension.

Stress is the force per unit area acting on a material (σ = F/A). Strain is the fractional change in length of a material due to stress (ε = ΔL/L). Both are important in characterizing material behavior.

The Young modulus (E) is a measure of a material's stiffness or resistance to elastic deformation under stress. It is defined as the ratio of stress to strain in the elastic region: E = stress/strain.

The limit of proportionality is the point beyond which Hooke's law is no longer obeyed. Beyond this point, the extension of a material is no longer directly proportional to the applied load, and the material may experience permanent deformation.