Scientific Ontology

\sigma

Mechanics

Stress

Force per unit area within a material (tensile or compressive).

pascal (Pa)

Dimension: $[\,M L^{-1} T^{-2}\,]$

How values of stress span the physical world (in Pa, log scale).

Bone

1.30 × 10⁸ Pa

Steel yield

2.50 × 10⁸ Pa

Lower limit10³ PaUpper limit10¹¹ Pa

Young Modulus

E = \dfrac{\sigma}{\varepsilon}

Tensile Stress

\sigma = \dfrac{F}{A}