Warp wrote:
>   If we express that in overly simple terms: If a rotating system consists
> of several parts, bringing those parts closer together requires energy.

Yes.

> If those parts are later pulled apart, that energy is released?

Assuming it hasn't dissipated somewhere, yes.  Think of spinning around 
an axle, reeling in a weight on a string. Now let the weight pay out, 
and you can make it do work like play a music box.

>   Or perhaps in another way: Bringing more variation to local spinning
> at different parts of the system requires energy,

I don't think the spinning and the energy are particularly connected. If 
you're talking about closed systems, the energy doesn't go away, it just 
moves around. It may move to a place (like heat) from which you can't 
move it back.

>   (In other words, in a closed system getting two discs to rotate
> independently in the same direction requires energy. Colliding those
> discs so that they will start rotating as one single object will release
> that energy?)

I don't think that's right, no. In a closed system, you can move energy 
around but not create or destroy it. Spinning them in opposite 
directions requires moving energy from somewhere else, like a spring or 
a chemical explosion or something. In a closed system, you can't get 
them both rotating in the same direction without something else rotating 
in a different direction.

-- 
   Darren New / San Diego, CA, USA (PST)
     Remember the good old days, when we
     used to complain about cryptography
     being export-restricted?

Post a reply to this message