| A machine is any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of tasks. It normally requires an input as a trigger, transmits the
modified energy to an output, which performs the desired task.
Mechanical mechanisms and machines have been in steady use to amplify the abilities of human beings since before written
records were available. The primary difference between simple tools and simple mechanisms or machines is a power source and a
somewhat independent operation. The term machine generally applies to an assembly of parts operating together to perform work.
Generally these devices increase intensity of applied force, changing direction of force,
or changing one form of motion or energy into another.
The mechanical advantage of a machine is the ratio between the resistance or load, and
the force required to overcome it, although this ratio is not entirely accurate as force is required to overcome friction, as well. To compensate for this, mechanical advantage is calculated as the ratio
between the distance moved by the force applied, and the distance moved by the resistance.
Efficiency of a machine is the degree or percentage to which a machine
accomplishes the work it could do without the restrictions of friction.
Modern power tools, automated machine tools, and human operated power machinery complicate this definition greatly. Machines
used to transform heat or other energy into mechanical energy are known as engines.
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