Moment Calculator

Moment Calculator


Moment
Force
Lever Arm Length

Definition

The turning effect of a force is known as the Moment i.e. Moment is the force attempting to produce motion around an axis. In other words, a force that attempts to produce motion around a given fixed point is called as a moment. The fixed point is often called the pivot or fulcrum. Forces that act on objects that have a fixed point – such as the hinge of a door, or the axle of a wheel make that object rotate.

Moment is the combination of weight and distance from the fulcrum. It is the product of the force multiplied by the perpendicular distance from the line of action of the force to the fulcrum or point where the object will turn.

When more than one force acts in the same direction, their overall turning effect is just the sum of their moments.

When forces act in a different direction, yet still balance, the total turning effect in each direction will be the same:
Sum of clockwise moments = Sum of anticlockwise moments

Formula

Moment is the product of the force multiplied by the perpendicular distance from the line of action of the force to the fulcrum or point where the object will turn. It can be calculated by the given formula :

Moment(N.m)[M] = Force(N)[F] × Perpendicular distance from pivot(m)[d]

Example:

1. Calculate the Moment around an axis if the force applied is 15N and the lever arm length is 20m?

Sol. :

M = F * d

M = 15(N) * 20(m)

M = 300 N.m

Moment of force is 300 N.m

2. In order to balance the 5 N force (clockwise moment) acting at 0.5 m from the pivot, what is the force, F(anticlockwise moment) required acting in the opposite direction but at 0.25 m ?

Sol. :

Clockwise moment = 5(N) × 0.50(m) = 2.50 Nm

Anticlockwise moment = F(N) × 0.25(m)

If the system is balanced, the anticlockwise turning effect of force F must equal the clockwise turning effect:

clockwise moment = anticlockwise moment

2.50 ( Nm) = F(N) × 0.25(m)

F = 2.5 / .25

F = 10 N

To balance the 5 N force acting at 0.5 m from the pivot, we require 10 N acting in the opposite direction but at 0.25 m.

Units

The standard unit of measurement of moment of force is Newton.meter i.e. Nm.