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



This is the sort of approach that I had heard about...it sounds very
interesting. One thing however, since force is in our common
vocabulary and sounds like physics, if you don't mention it at all, is
there a danger that the students will think they are learning about
something which is not really part of their world? Or do you bring in
force in at least casually, so they know it is part of the scheme of
things.
The danger is that the course could just be an academic experience for
the students, but has no real bearing on their lives.

joe
On Aug 10, 2005, at 12:56 PM, Brian Blais wrote:

Dan Crowe wrote:
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?


I teach a college-level, algebra-based physics course as part of a
general education requirement. These are students who may never have
had physics before, and it may be the last science course they ever
have. I've tried a number of difference approaches. and one that I
have
found successful is to avoid using the word "force" at all. In fact, I
don't use "acceleration" either. ;)

I start off with a small unit on estimation and large/small numbers.
Then I introduce conservation laws as a way of decribing the universe,
but also as a way to make inferences. Conservation of people, mass,
and
money are all relatively intuitive to students (as well as the
exceptions to these conserved quantities). I introduce energy for the
the "free fall" type of situations, and then momentum to deal with
collisions. When everything is in terms of energy and momentum, you
don't need to use force and acceleration as the primary quantities of
interest.

It flows naturally into relativity and quantum mechanics, where both
force and acceleration are not seen as the primary quantities of
interest, or at least not the most convenient.

Given one semester to teach "Physics", I've found this approach to be
very economical in terms of time, and yet I have not had to reduce my
expectations of the material covered.

Any thoughts?


Brian Blais


--
-----------------

bblais@bryant.edu
http://web.bryant.edu/~bblais


Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556