Re: CONSERVATION OF ENERGY

[brian whatcott <inet@intellisys.net>]

At 07:54 7/15/97 -0700, Leigh Palmer wrote:

[McGraw-Hill Encyclopedia of Energy]
> > "Energy: the property of a system that is a measure of its capacity for
> > doing work"
>
> In physics our definitions can be used to make calculations. This one
> can't be; it is not a physical definition, and in this case it is
> incorrect. This definition will suffice narrowly for watchsprings and
> reservoirs. It fails utterly for blocks of warm iron. It is neither a
> physical nor a complete lexical definition of energy. Among the many
> exceptions might I modestly suggest E=mc^2?
....
> Leigh

I believe I see the basis of Leigh's difficulty now; it is not difficult to
explain - in fact if I continue with the dictionary definition, that may be
sufficient:

"Because a system may possess an enormous store of energy that is not
available for doing work, energy is better defined as that property of a
system which diminishes when the system does work on any other system by an
amount equal to the work so done.....
  ..Internal energy is sometimes erroneously referred to as the "heat
energy" of a body. It is a property of a given state of a system, is
evidenced by certain other properties of the system, notably temperature
and is to be distinguished from from any kinetic or potential energy
possessed by the system as a whole in its relation to other systems..."

I wanted to end by quoting Feynman's 'parable of the blocks' (Vol 1, para
4-1) but I find it difficult to extract the essence of Leigh's sense of
perfect explanation.

Perhaps it lies here:
"Energy has a large number of different forms...kinetic energy, heat energy...
....nuclear energy, mass energy."
"It is important to realise that in physics today, we have no knowledge of
what energy is."

Regards
brian whatcott <inet@intellisys.net>
Altus OK