Engine

An engine (motor) is a machine designed to convert one form of energy into mechanical energy. Heat engines burn a fuel to create heat, which is then used to create a force. Electric motors convert electrical energy into mechanical motion; pneumatic motors use compressed air and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and eventually motion.

An engine can be put into a category according to two criteria: the form of energy it accepts in order to create motion, and the type of motion it outputs.


Heat Engine

Combustion engines are heat engines driven by the heat of a combustion process.

Internal combustion engine

External combustion engine



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Source: wikipedia