What Is the Law That Says You Can Only Get Out What You Put In?

[karae12]

i am trying to find the law or therory that states "you can only get out what you put in?" and if there is such a thing as a one to one barrier? anything things that has to do with equal parts in creates equal parts out applyed to motors or anything really...
please help me find the name of the law or person with the therory.

thank you!

 

[chroot]

The... first law of thermodynamics, perhaps?

- Warren

 

[FredGarvin]

Conservation laws?

 

[russ_watters]

You may as well just check out all three...

 

[imastud]

yeah conservation of energy

 

[mathlete]

Continuity equations, perhaps?

http://en.wikipedia.org/wiki/Continuity_equation