Changes

*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 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 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.

*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 have actually useful appliances e.g in the construction of flywheels.

==Examples==

==Examples==