Pulley

A pulley is a wheel with a groove along its edge, for holding a rope or cable. Pulleys are usually used in sets designed to reduce the amount of force needed to lift a load. However, the same amount of work is necessary for the load to reach the same height as it would without the pulleys. The magnitude of the force is reduced, but it must act through a longer distance. Pulleys are one of the six simple machines.

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A fixed or class 1 pulley has a fixed axle and is used to redirect the force in a rope (called a belt when it goes in a full circle). A fixed pulley has a mechanical advantage of 1.

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A movable or class 2 pulley has a free axle and is used to transform forces. A movable pulley has a mechanical advantage of 2. That is, if one end of the rope is attached to the fixed object, pulling on the other end of the rope will apply a doubled force to the object attached to the axle.

Wheel: A wheel is a circular object that, together with an axle, allows low friction in motion, by rolling. Common examples are found in transport applications. More generally the term is also used for circular objects rotating for other purposes, such as a wheel and axle and a flywheel....

Rope: : Rope is also the title of a movie by Alfred Hitchcock...

Cable: A cable is two or more wires bound together which may be bare or covered or insulated. It may be protected by a jacket sheath which protects all. Electrical cables can also act as carriers for other media, including optical fibers....