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Re: CONSERVATION OF ENERGY




On Fri, 25 Jul 97 07:45:58 EDT LUDWIK KOWALSKI
<kowalskil@alpha.montclair.edu> writes:
On Tue, 22 Jul 1997 Patrick Whippey <pwhippey@julian.uwo.ca> wrote:

I have spent the afternoon reading a new text "Physics: A
Contemporary
Perspective" by Randall Knight from Cal. Poly at San Luis Obispo,
Addison
Wesley. It is one of a new breed of textbooks that are beginning to
use
the insights that the Physics Education Research Community has
brought to
our attention. His discussion of the problem is superb, and I now
have
new insights into this problem of zero work forces, and where the
enrgy
goes when a block slides over the table. I think many contributers
to
this list would anjoy it too.

Thanks a lot. It is indeed a book which seems to be quite different
from
many. As I can see from Chapter 11, the sliding on the horizontal
surface
is one of several examples analyzed as an application of the
work-energy
relation for a system of particles. Looks promissing, will start
reading
carefully now. Here is another example (page 375).

A 1000 kg car traveling at 5 m/s runs into a solid, unbending wall.
The bumper and the front of the car crumple upon impact, resulting
in the car's center of mass moving forward before stopping. Analyze

and interpret the forces and energy transfers of this collision.

The entire page is devoted to this problem. The terminology is very
much
in line with what was emphasize in this thread. And how can I resist
mentionning that 'thermal energy' is in the author's vocabulary?

I received both volumes of the preliminary 1997 edition. The ISBN
codes
are: 0-201-43164-5 and 0-201-43165-3, paperback. If you are going to
Denver stop at Addison Wesley stand and browse the book. Talk to them;

perhaps you will also receive a complimentary copy.
Ludwik
Kowalski

The amateur has taught chemical engineering thermodynamics, perhaps not
well, but ...

Chemical engineers toss all that rise in entropy due to irreversibilities
into one of a number of objects called Lost Work (LW - not even W sub L).
Damn, I wish I had an equation editor because it is too hard to explain
without it. It began at Michigan with mechanical lost work
LW/T (See vanWylen and Sonntag) and was perfected at MIT as
thermodynamic lost work, LW/T(surr) (See Smith and vanNess). These are
terms that close the entropy balance and avoid using an awkward
inequality.

Regards / Tom

P.S. I need to discuss this more with Dave Bowman, Leigh Palmer, and
Jim Green. I have had a new and useful insight due to them.