Mechanical Reversibility vs Thermodynamical Irreversibility

[Batman]

I'm a bit confused with this topic we're supposed to be writing a paper on:
"Thermodynamical Irreversibility VS Mechanical Reversibility (Microscopic Nature of the 2nd Law of Thermodynamics)"

I think I know the concept of the irreversible nature of thermodynamics...such as the flow of thermal energy from hot to cold until equillibrium... entropy, and the nature of things to go from organization to lesser degrees of organization. But nowhere can I find the term "Mechanical Reversibility" and I don't really know what he means by it.

He gave us a couple of handouts that were supposed to help us. They both mentioned Perpetual Motion Machines... the main focus seemed to be Perpetual Motion Machines of the 2nd kind... that is, the kind that can extract heat from objects, against the laws of thermodynamics. Nonetheless, I can't seem to connect "Mechanical Reversibility" to any of this, as can't even find an example of it =(

Any ideas on what the term refers to? Thanks =)

 

[krab]

You posted this message in 2 different places. Under Classical Physics, I answered as follows: In Google, type in one or more of the following keywords: "maxwell's demon", ratchet, irreversibility. That ought to get you started.

 

[Batman]

Yeah, sorry about the double post. That was the first relevant forum I found, but then I saw this one and it seemed more relevant so I just re-posted it. Anyways the course is supposed to be really basic... he gave us nothing but multiple choice questions until now, when he suddenly came up with this paper idea. I'm not a major or anything and as such, everything I've found on the internet so far is WAY over my head. All I'm really looking for is a simplified example of mechanical reversibility, because nothing I've found so far will explain what it even means.

So essentially... what, regarding mechanics, is reversible? and how?

Thanks =)