Moment meaning in physics

Sometimes a force causes an object to rotate or turn. A moment is a measure of the turning effect of a force.

Factors affecting Moment or turning effect

The turning effect depends on two things:

• the magnitude of the force applied

• the perpendicular distance of the force from the pivot.

What is Pivot

A pivot is a point around which rotational movement takes place.

Moment Formula

moment = force × perpendicular distance from the pivot
M = F × d
Here, M = moment (N m)
F = force (N)
d = perpendicular distance from the pivot (m)

Moment Unit in SI

The unit of Moment in SI is Newton meter (N m).
[Note: The unit of force is the newton (N) and the unit of distance is the meter (m).]

Moment example [Spanner use]

The moment is greater if either F or d is increased. For example, to undo a tight nut with a spanner, you need a large moment.
This can be achieved by applying a large force with a spanner.
If a longer spanner is used, a smaller force is needed and it is much easier to undo the nut. The force is applied at a greater distance.

More Examples, where moments are important, include:

• door handles
• see-saws
• cranes
• levers.