Re: Why work before energy in texts

["John S. Denker" <jsd@MONMOUTH.COM>]

At 05:02 PM 10/14/01 -0400, Larry Cartwright wrote:
> Is is correct to say that work "becomes" energy, rather than "produces"
> energy or "results in" energy or some other way of describing the
> sequence?  I think what I'm asking is, does W-KE say work and energy are
> *identical* or merely *equal*?

IMHO none of the above.

Assuming that "work" means "F dot dx" I would say:
 ++ Work has dimensions of energy.
 ++ Work is a contribution to the energy budget.

I would also say:
 ++ Energy is primary and fundamental.  Pay attention to the
energy.  Anything you really need to know about work can be figured out by
paying attention to the energy.

Analogy:  Suppose you receive a $1000.00 cash bonus at the end of the
year.  I would say
 ++ The bonus has dimensions of money.
 ++ The bonus makes a contribution to your monetary budget.

However:
 -- I would not say the bonus "becomes" money.
 -- I would not say the bonus "produces" money, since the money already
existed.
 -- I would not say the bonus "results in" money.  It may result in _you_
having money, but it doesn't result in "money" in any broader sense.
 -- I would not say the bonus is "equal" to money, since there is lots of
other money in the world.
 -- I would not say the bonus is "identical" to money, since "identical"
is an even stronger statement than "equal".

=================================

General pedagogical point:  I get a lot of mileage out of the analogy:
  energy <==> money
It's not a perfect analogy, since energy is much more strictly conserved
than money is -- but my students typically have a reasonable intuition
about monetary transactions as a zero-sum game.  This gives me a starting
point.  As the saying goes, learning proceeds from the known to the unknown.

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I reiterate my objection to the Subject: line of this thread.