Principle of Moment

What does the principle of moments state?

It states that when a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anti-clockwise moments about the same pivot.

Classic Principle of Moment Questions

1. Explain briefly how the use of a screwdriver enables the lid of a paint can to be opened with a relatively small force.

• Moment is the product of force and the perpendicular distance between the force and the pivot.
• When a force is applied at the far end of the screw driver, the perpendicular distance between the pivot and line of action of applied force is large.
• This will then produce a large moment to open the paint can.