The last night posting (about "internal" and "thermal" energies), directed
to xyz, was not answered. Can somebode else comment on it?
Ludwik Kowalski
P.S.
I wish I could ask Feymnan who wrote (vol I, p 4-33):
"Let us begin by stating the first law, the conservation of energy: if one
has a system and puts heat into it, and does work on it, then its energy
is increased by the heat put in and the work done. We can write this as
follows: The heat Q put into the system, plus the work done on the system,
is the increase in the energy U of the system; the latter energy is
sometimes called the internal energy."