Paul Fuller <pgf### [at] optusnetcomau> wrote:
> >   In order for the rotating secondary object to affect the primary object's
> > rotation, it has to be connected to the primary object somehow. This
> > connection causes friction.
> It has to exert a force and I agree that some energy will be lost in any 
> practical system.  You are just not getting the point that friction 
> itself has nothing to do with angular momentum.

  So you are effectively saying that regardless of heat produced by
friction, angular momentum is always conserved. This would effectively
make a spinning object an infinite source of energy.

> >   This would be true in a completely friction-free system. The thing is,
> > friction dissipates part of this energy.
> Still hung up on friction !

  A spinning object can be used to produce heat by friction.

> True enough.  Friction is the mechanism that takes energy from the 
> spinning Earth.

  Where does this energy come from?

>  At the same time there is a change elsewhere in the 
> system that conserves angular momentum overall.

  Which means that the energy was produced completely for free?
Isn't that kind of the definition of a perpetual motion machine?

> The tidal locking effect is well known and you have described it 
> reasonably well.  However you are wrong to say that angular momentum is 
> converted to heat by friction.

  Then what is it that is converted to heat by friction?

> Angular momentum is a different thing to energy.  Sorry but there is no 
> known way to convert one to another.  You can certainly use energy to 
> start one mass spinning.  Thing is that there must be an opposite amount 
> of angular momentum showing up somewhere else.

  Two objects with no angular momentum at all collide off-center, and
they get stuck to each other. The resulting union of masses will start
spinning because of the collision.

  Somewhere else in the universe something else starts spinning in the
opposite direction due to a magical universal conservation of angular
momentum law.

  Yes, I understand perfectly now. Thanks for clearing that up.

-- 
                                                          - Warp

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