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Re: ENERGY WITH Q



"John S. Denker" wrote:

Ludwik's exposition has not provided a sufficiently-clear
distinction between thermal energy and nonthermal energy.
We were looking forward to getting one.

IS THIS ACCEPTABLE?

In many textbooks thermal energy, which is really
mechanical energy of randomly agitated molecules
and atoms, is referred to as internal energy. In my
opinion this term is not desirable because “internal"
could easily be misinterpreted as “all energy inside
a system”. This would be wrong, some energy inside a
system can be nonthermal. Think about a system
containing compressed springs and rotating wheels.

At the macroscopic level we can say that thermal
energy is the energy a system has by virtue of its
temperature. At the microscopic level we can say
that thermal energy is the mechanical (kinetic and
potential) energy of molecules. The nonthermal
energy of a system is its Etot-Eth.

The trouble I have with terminology (thermal versus
internal) is that the so-called "energy state", for
example, for a molecule, is determined by its total
energy and the idea of thermal energy does not
apply to a single molecule. Do we really need the
term "internal"? What is wrong with keeping only
thermal, non-thermal and total?
Ludwik Kowalski