• id: JME-08-N05
• title: Young's Modulus — Definition and Calculation
• tags: youngs-modulus, longitudinal, wire

Young's Modulus measures a solid's resistance to longitudinal deformation: $Y = \frac{\text{Longitudinal stress}}{\text{Longitudinal strain}} = \frac{F/A}{\Delta L/L} = \frac{FL}{A\Delta L}$ SI unit: Pa (N m$^{-2}$). Dimensional formula: [M L$^{-1}$ T$^{-2}$]. It applies to solids only (liquids and gases cannot sustain tensile/compressive stress without flow). The higher the $Y$, the stiffer the material. Steel ($Y = 200$ GPa) is stiffer than rubber ($Y = 0.01$ GPa). On a stress-strain graph, $Y$ equals the slope of the linear region.