Re: CONSERVATION OF ENERGY

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

I can not resist showing you, Leigh, that you too can be inconsistent. 
I am reading everything you wrote again and here what I see.

Sunday morning: 

> Let us examine the therm "thermal energy". This term is not in my 
> dictionary, nor should it be in that of any physics teacher. It is 
> a source of confusion .... and a barrier to conceptual grasp.

Monday afternoon: your formulation of the first law:

> The change in thermal energy of a system is a sum of the heat that
> flows into it and that part of the work that is done on it that does 
> not appear as a change in the kinetic energy of the center of mass
> of the system.

Nobody is perfect, right? Perhaps you would not mind commenting on the 
"how slow is slow enough" question formulated below.
                                                     
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It occured to me, while thinking about our subject, that the "accepted"
thermodynamic definition of heat also has some built-in ambiguities. By
saying "heat is that part of internal energy which is impelled (transfered)
from A to B because T(A) is larger that T(B)" we are implying that T(A) 
and T(B) are defined during the process. This is not necessarily true for 
"fast" processes, for example when A is a brick-like block of Cu at 400 K 
while B is a similar block at 600 K. Put A on top of B and you have a non-
equilibated system. The final temperature, under ideal conditions, will
be 500 K but the intermediate temperatures have no meaning. I wander "how
slow" is slow enough to make intermediate temperatures meaninful?

                                                    Ludwik Kowalski