What does the modulus of elasticity measure in materials?

The modulus of elasticity is a fundamental property of materials that quantifies their stiffness, which refers to the material's ability to deform elastically (i.e., non-permanently) when a force is applied. It is defined as the ratio of stress (force per unit area) to strain (deformation per unit length) within the elastic limit of the material. A higher modulus of elasticity indicates that the material is stiffer and less prone to deformation under applied loads.

In practical terms, materials with a high modulus of elasticity, such as steel, will exhibit minimal deformation when subjected to stress, making them suitable for applications requiring rigidity and strength. Conversely, materials with a low modulus of elasticity, like rubber, will deform more easily under the same load, indicating greater flexibility. This distinction in stiffness is crucial in engineering and design, as it helps in selecting appropriate materials based on their expected performance under various loading conditions.