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perpetual motion

per·pet·u·al mo·tion


noun 
Definition:
 
1. hypothetical motion: the hypothetical continuous operation of a mechanism without the introduction of energy from an external source, known as perpetual motion of the first kind. A device demonstrating this would violate the first law of thermodynamics, which states that energy can neither be created nor destroyed.

2. hypothetical conversion of heat: the hypothetical operation of a mechanism that would convert heat directly into work, known as perpetual motion of the second kind. A device demonstrating this would violate the second law of thermodynamics, which states that heat cannot be converted into work without producing some other effect.

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