[Phys-L] Re: Energy is primary and fundamental? (was RE: First Day Activities or Demos)

[rmcder at PEOPLEPC.COM (R. McDermott)]

----- Original Message -----
From: "Dan Crowe" <dcrowe@SOTC.ORG>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Wednesday, August 10, 2005 1:09 PM
Subject: Energy is primary and fundamental? (was RE: First Day Activities or
Demos)


> John,
>
> Some physicists advocate starting a first course in physics at the high
> school level with energy and energy conservation, but I don't know how
> to do that.
>
> How do you define energy without reference to force or work?
>
> How can high school students develop an understanding of energy and
> energy conservation at the beginning of their first course in physics?
>
> What guidance should a teacher provide in this process?
>
> Daniel Crowe
> Oklahoma School of Science and Mathematics
> Ardmore Regional Center
> dcrowe@sotc.org

Dan,
The Modeler's definition of energy is somewhat different from the classic
"energy is the capacity to do work", which requires you to define work and,
as a result, drag in the discussion of force.  Instead we have something on
the order of "energy is the capacity for change", so the emphasis is on the
location(s) of energy and the specific changes that occur as a result of an
energy increase or decrease.  An energy change can result in changes in
motion (kinetic energy change), positioning (potential energy change),
arrangement (potential energy change), etc.  Working, radiation, and heating
only come in at the stage where one becomes concerned about HOW energy
transfers from one thing to another.  All of this allows you to discuss
energy right away if you think it's appropriate.

Note that this approach pretty much requires that fields be considered as
"objects" rather than theoretical constructs, since for the Modeler, energy
always has to reside "somewhere", and my personal approach to this is to
liken fields to springs or rubber bands whose geometry changes as energy
changes.  That's a lot farther down the road, of course, but it is a bridge
one has to cross eventually if one is to be consistent.