Re: ENERGY WITH Q

[Robert Cohen <Robert.Cohen@PO-BOX.ESU.EDU>]

Referring to this:

> As I indicated last night, the expression Q+W is likely to be
> responsible for a misconception that work is a form of energy.

I wrote:

> If Q was interpreted to be a form of work instead of energy, would
> the expression Q+W still lead to the misconception that W is a form
> of energy (since the left-hand side is energy)?  I'm thinking of a
> similar conception regarding F=ma, i.e., that ma is a form of force.

Ludwik Kowalski then responded:

> In my sequence Q would be introduced in calorimetry. How
> can it be "interpreted" as force*distance?

and Jim Green responded:

> Absolutely, Robert.  If in these discussions we would stop
> reifying energy
> and Q and saying things like "flow", converted, and
> transferred, then  the
> understanding of the matter would grow.

It seems to me that what we do depends on where we started.  Do we start
with Q being energy transfer?  If so, then adding W on the same side seems
to confuse things and we want to interpret W as a type of energy.

On the other hand, do we start with W being work?  If so, then adding Q on
the same side seems to confuse things and we want to interpret Q as a type
of work.

My comment (see above) was made only to point out that addressing the Q vs.
W confusion by redefining W seems equivalent to addressing it by redefining
Q.

How about if we rewrite the expression as
      deltaE +/- Q = W?

Here deltaE is energy, Q is energy and W is work.  Does this solve the
likely "misconceptions" that might arise when energy and work are on the
same side of the expression?  What are we really trying to address here?
Whether we think in terms of energy or in terms of forces, it is the same
physics.  How much redefining are we willing to put up with to make things
easier conceptually for the students?

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Robert Cohen           rcohen@po-box.esu.edu
570-422-3428         http://www.esu.edu/~bbq
Department of Physics
East Stroudsburg University
East Stroudsburg, PA  18301
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