Moments and Turning Effect

Moments and the Turning Effect of Forces

The moment of a force is its turning effect about a pivot.

Definition
Moment is the product of the force and the perpendicular distance from the pivot.

$$\text{Moment} = F \times d$$

where $F$ is the force (in N), $d$ is the perpendicular distance (in m), and the unit is Nm.

Keywords

Keyword	Meaning
Moment	Turning effect of a force.
Pivot	Point where turning occurs.
Perpendicular distance	Shortest distance from pivot to force line.
Clockwise moment	Moment that turns clockwise.
Anticlockwise moment	Moment that turns anticlockwise.
Equilibrium	Balanced – no turning.
Force	Push or pull on a body (in Newtons).

Principle of Moments
At equilibrium, the total clockwise moment equals the total anticlockwise moment.

Conditions for Equilibrium

1. No resultant force acts on the body ($F\_{\text{net}} = 0$).
2. Resultant moment is zero (total clockwise moment = total anticlockwise moment).