The principle of moments
• The principle of moments says a system is in equilibrium when clockwise moments and anticlockwise moments are equal.
• A moment is a turning force that tries to rotate an object around a pivot.
• It is calculated using M = F × d, where F is the force and d is the perpendicular distance from the pivot.
• This principle is used in everyday tools like levers, seesaws, and similar devices to balance forces or lift heavy loads.
• The principle only works when the object is in equilibrium (not moving or rotating).
• Moments depend on direction (clockwise or anticlockwise), so you must keep track of which way each force tries to turn the object.
• If the moments are not equal, the object will rotate in the direction of the larger moment.
• A tiny force can create a large moment if the distance from the pivot is long (this is why long levers make lifting easier).