# Moments

Moments are also known as ‘turning force’ or ‘torque’. These forces take place about a pivot.

**Moment = Force x Perpendicular distance of the line of action
of the force from the pivot**

**The principle of moments**

1. For any object that is at equilibrium the sum of the clockwise moments
is equal to the sum of the anticlockwise moments about the same point.

2. For a body to be at equilibrium the resultant force on it is zero.

**Example applying the principle of moments**

The following object is at equilibrium. Find the angle between 6N to the
vertical.

Taking moments about the pivot

Sum of the anticlockwise moments = Sum of the clockwise moments

0.75 x 10 = 8 Cos(x)

Cos^{-1}(7.5 / 8) = 20.36º

**Centre of Gravity**

The centre of gravity is defined as the point at which the entire weight
of a body can be considered to act.

Couple

A couple is a pair of forces equal in magnitude and opposite in direction, which produce rotation but not acceleration.

The moment of a couple = Force x Perpendicular distance

**Reference Tools**

Dictionary

Thesaurus

Maps

Scientific Calculator

Periodic Table

Translator

Unit Conversion

**Module 1**

Useful Physics Resources

Scalars, Vectors & Graphs

Fundamental Equations and Complex Vector Equations

Equations of Motion

Moments

Pressure, Work, Energy and Power

Deformation of Solids

Car Safety