The dimensional formula $[ML^{-1}T^{-2}]$ is common to several physical quantities defined by force acting over an area. Pressure is defined as the normal force per unit area ($P = F/A$) and has dimensions $[ML^{-1}T^{-2}]$ . Stress is defined as the restoring force per unit area and shares the same dimensional formula, $[ML^{-1}T^{-2}]$ . Young's Modulus is the ratio of tensile or compressive stress to longitudinal strain . Since strain is a dimensionless ratio ($\Delta L/L$), Young's modulus has the same dimensions as stress, which is $[ML^{-1}T^{-2}]$ . Consequently, all three quantities share this dimensional formula .