Elastic Modulus (Young's Modulus)
Definition
A measure of a material's stiffness, defined as the ratio of stress to strain in the linear elastic region. Denoted as E, it represents how much a material will deform under a given load.
Practical Note
Steel has an elastic modulus of about 200 GPa, while aluminum is around 70 GPa. Higher modulus means less deflection under the same load.