5.4 - Moments, levers and gears

• The moment of a force is the turning effect of that force.
• distance is the perpendicular distance from the pivot to the line, in metres
• If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot. This is the principle of moments
• A simple lever and a simple gear system can both be used to transmit the rotational effects of forces
• Levers are force multipliers. They allow us to lift a heavy object by applying a relatively small amount of force.
• Gear systems are also force multipliers. They allow us to increase or decrease the speed at which something turns. In the diagram we can see that because gear B has twice the radius of gear A, the turning effect of gear B is twice as large as gear A. Gear A rotates twice every time gear B rotates once. This means they have the same work done.