Written by Jerry Ratzlaff on . Posted in Classical Mechanics


Stress ( \(\sigma\) (Greek symbol sigma) ) or ( \(S\) ) is the force per unit area of cross-section.  The maximum stress of a material before it breaks is called breaking stress or  ultimate tensial stress.

Stress formula

\(\large{ \sigma = \frac{F}{A} }\)


\(\large{ \sigma }\) (Greek symbol sigma) = stress

\(\large{ F }\) = force

\(\large{ A }\) = cross-section area

Solve for:

\(\large{ A = \frac{F}{\sigma} }\)

\(\large{ F = \sigma A }\)

Longitudinal Stress

The stress imposed on the long axis of any shape. It can be either a compressive or tensile stress.

Shear Stress

Shear Stress FORMULA

\(\large{ \tau = \eta \cdot \dot {\gamma}  }\)


\(\large{ \tau }\) (Greek symbol tau) = shear stress

\(\large{ \eta }\) (Greek symbol eta) = viscosity

\(\large{ \dot {\gamma} }\) (Greek symbol gamma) = shear rate


Tags: Equations for Stress