What property of a material does Young's modulus measure?

Young's modulus is a fundamental mechanical property that quantifies the stiffness or elasticity of a material. It is defined as the ratio of tensile stress (the force applied per unit area) to tensile strain (the deformation or elongation per unit length) in the region of the material's elastic deformation, where the material returns to its original shape after the load is removed.

The significance of Young's modulus lies in its ability to indicate how much a material will deform under a given load. A higher Young's modulus value suggests that the material is stiffer and will deform less when subjected to stress. Conversely, a lower value indicates more flexibility and a tendency to deform more under the same amount of stress. This property is critical in engineering and material science, as it helps in selecting appropriate materials for structural applications based on their expected performance under various loading conditions.

In contrast, ductility refers to a material's ability to deform plastically before fracture, hardness measures resistance to localized plastic deformation (like scratching), and tensile strength indicates the maximum amount of tensile stress a material can withstand before failure. These properties are distinct from stiffness or elasticity, which is captured directly by Young's modulus.