How do you calculate the moment of a force?

To calculate the moment of a force, multiply the force by the perpendicular distance from the pivot.

In more detail, the moment of a force, also known as torque, is a measure of the turning effect of the force on an object. It is calculated using the formula:

\[ \text{Moment} = \text{Force} \times \text{Perpendicular Distance} \]

Here, the force is the push or pull applied to the object, measured in newtons (N). The perpendicular distance is the shortest distance from the pivot point (or fulcrum) to the line of action of the force, measured in metres (m). The pivot point is the point around which the object rotates or turns.

For example, if you apply a force of 10 N to a spanner at a distance of 0.5 m from the nut (the pivot), the moment of the force is:

\[ \text{Moment} = 10 \, \text{N} \times 0.5 \, \text{m} = 5 \, \text{Nm} \]

This means the turning effect of the force is 5 newton-metres (Nm).

It's important to note that the distance must be perpendicular to the direction of the force. If the force is not applied perpendicularly, you need to find the component of the force that is perpendicular to the distance. This can be done using trigonometry if the angle between the force and the distance is known.

Understanding moments is crucial in many real-life applications, such as using levers, opening doors, and even in engineering structures. By analysing moments, you can determine how forces will cause objects to rotate and ensure that structures are stable and safe.