Re: CONSERVATION OF ENERGY

[twayburn@juno.com (Thomas L Wayburn)]

On Thu, 24 Jul 97 09:24:40 EDT "Emilio O. Roxin" <EROXIN@URIACC.URI.EDU>
writes:
> Hi!
>   In line with the opinion that we need two different words for
> "making the temperature rise",depending on the fact that there are
> bodies of different temperature present or not, which leads to 
> carefully
> distinguish "warming" from "heating", I see the great necessity to 
> find
> a new word to also distinguish "cooling" (when differenet temperature
> bodies are in contact) from the situation when this is not the case
> (for example the adiabatic expansion of a gas).

Tom,  the amateur,  writes:
First, I would distinguish the verb "to heat" from the noun "heat", 
which is best done, probably, by dropping the verb from physics.

>   On this subject, I wonder how people would explain the following
> two processes:
>   a) I have two containers, A and B, joined by a tube with a valve.
> A is empty (vacuum), while B contains air at normal pressure. I open
> the valve, so that the air also gets into A without producing any 
> work.

Let the control volume be container A:  The air in B has enthalpy, h,
entropy, s, and Gibbs availability, h-T(surr)s,  before the experiment
and such portion of it as ends up in A has internal energy, u,  entropy,
s, and Helmholtz availability, u-T(surr) s, after the experiment.
The First Law is easy, the Second Law is made into an entropy balance by
using the Lost Work Term,  (LW)/T(surr) , to close the balance.  The
Combined First and Second Law is also easy to write.    The
irreversibility is not troublesome.   The control volume, B, is easy to
treat too.   But, it's too much of a drag on e-mail without an equation
editor and graphics.   Th next problem is simple too.  Regards / Tom
>   b) In a container (usually a cylinder with a piston) I have a
> mixture of air and gasoline vapor. I ignite it via a spark plug and
> the temperature rises.
>   Regards     Emilio