A single fixed pulley has a mechanical advantage of 1:1. Mechanical advantage, which is correlated to the usefulness of a machine, refers to the proportion of force output to force input. Force output refers to the force exerted by the machine, while force input refers to the applied force.
Machines are devices that utilize mechanical or electrical power to perform a variety of functions. Mechanical machines are contraptions that increase work capacity and efficiency by providing added energy to carry out certain activities.
There are two classifications of mechanical machines: simple and compound. Simple machines are composed of a single mechanical apparatus. The six types of simple machines include the wheel and axle, simple lever, simple inclined plane, pulley, wedge and screw.
A pulley consists of a wheel having a corrugated rim with a length of rope, string, cord or chain running along the rim. This simple machine is typically used to hoist or lower down a load, particularly heavy objects.
The mechanical advantage of a pulley system is determined by the number of ropes hanging on the sides of all pulleys that are working against gravity. A single fixed pulley uses only one rope, where the load is lifted by the same distance as the other end of the rope is pulled down. In a 1:1 mechanical advantage, the applied force is the same regardless of the pulley being used.