What term describes the ratio of stress to strain below the proportional limit?

The ratio of stress to strain below the proportional limit is described by Young's modulus. Young's modulus is a fundamental property of materials that measures their elasticity. It quantifies how a material will deform under stress, specifically in the linear region of the stress-strain curve, which is the area below the proportional limit where the material behaves elastically according to Hooke's Law.

In this region, stress (the force applied per unit area) is directly proportional to strain (the deformation or displacement experienced by the material), and Young's modulus is calculated as the slope of the linear portion of the stress-strain curve. This property is crucial in engineering and materials science as it helps determine how materials will perform under various loading conditions.

Other terms listed have distinct definitions and applications. The modulus of rigidity, for example, relates to shear stress and strain, while Poisson's ratio describes the ratio of lateral strain to axial strain. Hooke's constant is not commonly used as a standalone term in materials science, and it can be confused with the general relationship advocated by Hooke's Law.