Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: A "heat" question



At 03:00 29 11 2002 , the following was received:
Carl Mungan wrote:

> Each iteration of the heat, work, and energy discussions slowly
> evolves my understanding. What a thorny topic. But worthy of
> consideration, not just stubbornly clinging to current notions.

The problem, Carl, may be just that we mindlessly continue to regard the
teachings of Aristotle highly -- He taught that the Universe is composed of
earth, water , air and --- fire, It ain't. We would be far better off
forgetting the sage and starting over. As a matter of fact we should also
abandon Carnot -- Who was a politician's son who dabbled with the issue of
war machines. The war machine of the day was the steam engine -- In order
to deal with England, France had to develop a better steam engine. Carnot
reduced the problem to an adiabatic cylinder with a piston and some warped
ideas based on Aristotle. We have been stuck with these ideas ever since.

A major result of this thinking was the First Law - which ain't worth a
damn -- except to engineers who do physics by looking in tables.

The only time the First Law makes sense is with regard to this very
cylinder invention of Carnot -- which reduces after some intelligent
thought -- to doing WORK with hot things and doing work with cold things.

There is NO difference in the First Law between Q and W -- They are both
WORK -- Neither "flows" or is a substance -- Certainly neither is
"energy". The work/energy theorem is still l valid

To this point I think that John and I agree. The difference comes in the
idea of "energy" in motion -- I hold that energy is a property of a system
and does not flow/transfer from one system to another -- The system can
move, but the property of energy can't move independently of the system --
any more that the property of color of the system can move independently
of the system. (Yes, John, I can see that the analogy isn't perfect --- no
analogy is -- but I think that this makes the point.)

And John and I agree that the focus here should be entropy.

In Carnot's cylinder the difference between Q and W (by moving the piston)
is that moving the piston doesn't change the entropy. I don't know of any
other situation where this occurs. All other forms of Q and W actions all
change S. (I would be very appreciative of hearing of a counter
example.) So w/o Carnot's damn cylinder we would not be having this
discussion. And w/o Aristotle's nutty ideas we would not have Carnot's
nutty ideas.


This posting has the blessing and agreement with SUNY-BSC, NAU or the AAPT
despite the reluctance of the mindless listserve machine.


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.