Pulley

Principles of Science: Mechanical Advantage, Work

The amount of force required to lift the object depends on the number of pulleys used. Each time a pulley is added the object becomes easier to lift. However, each time a pulley is added, the object is lifted a smaller distance. Less force requires a greater distance to complete a certain amount of work.

Pulleys are simple machines, and simple machines make work easier. Pulleys and gears are forms of levers. A pulley or gear is really a series of levers in a circle, the length of the lever is the radius of the pulley or gear.

The pulley, really a lever, can be connected to other objects using a cable or rope. A pulley can be used to draw water from a well, and the right gear can make it easy to pedal a bicycle uphill.