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[[image:perpetuumMobile.png|thumb]]

[[image:perpetuumMobile.png|thumb]]

A '''Perpetuum Motion''' (lat: eternal movement) device is a hypothetical machine that can produce work indefinitely without energy source or produce more energy than they consume.

A '''Perpetuum Motion''' (lat: eternal movement) device is a hypothetical machine which is said to be able to produce work indefinitely without energy sources or produces more energy than it consumes.

A great number of inventors claim that they have build a perpetual motion machine, but none of them could prove it. Often these claims were made by fraudsters and scammers. Since such a device would violate the laws of thermodynamics, it is also scientific consensus that it is impossible. Despite that fact, the pursuit of perpetual motion remains popular.

A great number of inventors claim they have built a perpetual motion machine, but none of them succeeded in proving this. Often these claims were made by fraudsters and scammers. Since such a device, if working, violated the laws of thermodynamics, it is also scientific consensus that it is impossible. Despite this fact, the pursuit of perpetual motion devices remains popular.

==Classes of Perpetuum Motion devices==

==Classes of Perpetuum Motion devices==

[[image:pmleonardodavinci.jpg|PM nach Leonardo da Vinci|left|thumb]]

[[image:pmleonardodavinci.jpg|PM according to Leonardo da Vinci|left|thumb]]

[[image:BesslerRad.jpg|PM Bessler Rad|200px|thumb]]

[[image:BesslerRad.jpg|PM Bessler Rad|200px|thumb]]

From a theoretical point of view these machine are classified by the law they would violate:

From a theoretical point of view, these machine are classified by the law they would violate:

*Perpetuum Motion device of the first kind: This machine produces energy without input or more that it consumes and violates the first law of thermodynamics. This kind is also called "overunity" by its fans.

*Perpetuum Motion device of the first kind: This machine produces energy without input, or more energy than it consumes, and therefore violates the first law of thermodynamics. This kind is also called "overunity" by its supporters.

*Perpetuum Motion device of the second kind: This machine converts heat to mechanical energy. Since this cools the environment, it cannot go on forever and violates the second law of thermodynamics.

*Perpetuum Motion device of the second kind: This machine converts heat to mechanical energy. Since this cools the environment, it cannot go on forever and violates the second law of thermodynamics.

*Perpetuum Motion device of the third kind: A machine that can run indefinitely without doing any work. The idea is that if friction is completely removed such a machine might run forever. And while it is impossible to reach that goal, it is possible to come pretty close. It has actually useful appliances e.g in the construction of flywheels.

*Perpetuum Motion device of the third kind: A machine that runs indefinitely without doing any work. The idea is that, if friction is completely removed, such a machine might run forever. And while it is impossible to achieve, it is however possible to come pretty close. Such devices has actually useful appliances e.g in the construction of flywheels.

==Examples==

==Examples==