Site hosted by Build your free website today!

Turning effects of forces

| Moments | Principle of moment | Centre of gravity | Stability | Quick Summary |


Moment is the turning effect of forces.

Moment of force = Force X perpendicular distance from the line of action of the force to the pivot

      Moment = F X d

Click to see video

The SI unit of the moment of force is measured in Newton metre (Nm).

Principle of moment

Principle of moment states that:

When a body is in equilibrium, the sum of clockwise moments about the balance point is equal to the sum of anticlockwise moments about the same point.

click to see video

Center of Gravity

The centre of gravity of an object is the point where the whole weight of the object seems to act.

Balancing cardboard and dustpan. 

For a regular object, the centre of gravity is at its centre and, where supported there, it balances.





Stability is a measure of a body's ability to maintain its original position.
If it returns to its original position after being displaced slightly, it is said to be in stable equilibrium.
If it continues to move away from its original position after being displaced, it is said to be in unstable equilibrium.
If it remains wherever it is displaced, it is said to be in neutral equilibrium.

The stability of a body can be increased by:

  1. Lowering its centre of gravity.
  2. Increasing the area of its base.



Quick Summary


^ Top