What is a perpetual machine and how do first and second kind differ?

[Krishna0703]

hi everybody, i have a question to which am unable to find the answer.
what is a perpetual machine?
this is related to thermodynamics and also what i understood there is a first kind and a second kind also...any detailed info from anyone please..
thanks

 

[Doc Al]

See: http://en.wikipedia.org/wiki/Perpetual_motion"

 

[vivek.iitd]

Perpetual machine is the one which can produce useful work indefinitely. They can do more work (produce more energy) than they actually consume. They are of course hypothetical though as they violate the principles of thermodynamics.

 

[Krishna0703]

thanks ...