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Re: Kinetic Energy elephant re-examined by formerly-blind person



Carl Mungan wrote:

You lost me here. Isn't rotational KE a prime example of nonthermal
energy? So why would you want to include that in a "thermodynamic
viewpoint"? Surely flywheels are covered in mechanics not thermo
class. I'm probably simply missing your point.

Actually Carl makes my point better than I did.
I inadvertently crosswired the front of one idea
with the back of another idea. See if this
revised version is any better:

There are innumerably many gray areas between these
extremes. We might call these mesoscopic viewpoints.
Among these is the view that divorces mechanics from
thermodynamics, as exemplified by a spinning flywheel:
in mechanics class, if somebody asks you to calculate
``the" KE of the flywheel you probably aren't expected
to include the KE of the ultramicroscopic thermal
agitation, just the rotational KE. For a flywheel,
-- The holoscopic KE is zero, because the center
of mass isn't moving;
-- The mesoscopic KE is the usual rotational KE;
and
-- The ultramicroscopic KE includes the above
plus the thermal agitation. In this viewpoint, the
thermal KE is the largest contribution unless the
flywheel is rotating pretty fast.

If somebody asks you to calculate the thermal KE, you
aren't expected to include the organized rotational KE.
So you would have to evaluate KE[microscopic] and
subtract off KE[mesoscopic].

(Check out
http://www.monmouth.com/~jsd/physics/kinetic-energy.htm
to see this in context.)

See also next msg.