A
simple machine is a mechanical device that changes the direction or magnitude of a
force. In general, they can be defined as the simplest mechanisms that use
mechanical advantage (also called
leverage) to multiply force. Usually the term refers to the six classical simple machines which were defined by
Renaissance scientists:
A simple machine uses a single applied force to do
work against a single load force. Ignoring
friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the
mechanical advantage.