# Torque

Torque, abbreviated as \(\tau\) (Greek symbol tau) or T, also called moment of force, is a rotational moment. It is a measure of how much twisting is applied to a fastener. The units used to measure torque are in the form of force times length. Usually measured in newton-metres (Nm) if metric units are used or pounds feet (lb-ft) when imperial units are used.

### Torque formula

\(\large{ \tau = l \; F }\)

\(\large{ \tau = d \; F }\)

\(\large{ \tau = I \; \alpha }\)

Where:

\(\large{ \tau }\) (Greek symbol tau) = torque

\(\large{ \alpha }\) (Greek symbol alpha) = angular acceleration

\(\large{ d }\) = distance

\(\large{ F }\) = force

\(\large{ l }\) = length, moment arm

\(\large{ I }\) = moment of inertia

Solve for:

\(\large{ d = \frac {\tau}{F} }\)

\(\large{ F = \frac {\tau}{l} }\)

\(\large{ F = \frac {\tau}{d} }\)

\(\large{ l = \frac {\tau}{F} }\)

## Breakaway Torque

The torque necessary to put into reverse rotation a bolt that has not been tightened.

## Breakloose Torque

The torque required to effect reverse rotation when a pre-stressed threaded assembly is loosened.