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CONSERVATION OF ENERGY



I don't have a coherent rsponse to the thread, but I'd like to make a few
comments.
1. With respect to the original problem situation: there appears to be a
basic confusion about the identity of the SYSTEM. If it includes the two
iron components, then the Work done ON the system is zero. If the system
as described is isolated then dQ is also zero, and the total energy internal
to the system is constant. These are the quantities related by the first
law of thermo.

2. I'll repeat my position of the last go-round on this topic; HEAT is the
energy transferred by virtue of a difference of temperature.
Heat as a verb is problematic.
Only in the simplest of systems, eg water in a test tube over a flame,
can you identify the HEAT with c*m*dT. I would call the latter quantity
the energy required to change the temperature of the mass.

3. I am troubled by application of the term 'Internal Energy' and its confusion
with situations in which temperature or internal states change. Internal
Energy, IMHO, is just the energy inside a stated boundary. It can be kinetic,
eg if the boundary contains discrete masses, or even reflect rotation of the
system.

4. I am very uncomfortable with systems far from equilibrium and uniformity.
If the system has 'lumps', such as the original problem, how do we describe
the various thermodynamic variables?

5. As far as friction is concerned, it is clear that surface deformations
occur on BOTH surfaces in contact, so that as accompanying adhesions rupture,
energy is deposited in BOTH objects. The immediate partition of energy is
NOT by conduction. I have seen no theory that would predict how the energy
is distributed. Sherwood, for example, assumes equal deformations, and therefor
gets an equal distribution.
Treating friction between rigid bodies by the usual technique hides
all the Physics occuring at the surfaces. The surfaces in contact are
deformable, as well as extremely non-uniform, etc.