Re: positive and negative work

[John Barrer <forcejb@YAHOO.COM>]

I think the key is "which students". If we're talking
about an introductory course, then maybe it IS worth
considering alternative explanations such as Scott
suggests that enhance, rather than inhibit, beginners'
(many of whom are still largely concrete thinkers)
understanding of concepts. That small percentage of
our students who go further in science and engineering
are, IMO, perfectly capable of later on making sense
of the language that defines a system's energy loss as
positive work done by the system or negative work done
on the system. Why do we saddle beginners with this
baggage when they're just trying to get the basics??
I've found that HS students can readily understand and
use energy changes to analyze situations without ever
having to describe the work as positive or negative.
John Barrere
--- Michael Edmiston <edmiston@BLUFFTON.EDU> wrote:
> Scott Goelzer asks whether it is really important to
> have students memorize
> arbitrary sign conventions.  In my response to this
> I'm going to be a bit
> sarcastic.  I'm not picking on Scott because he is
> asking an important
> question that goes beyond physics.
>
> I would answer this by saying it's not important,
> don't bother to teach
> students any arbitrary conventions.  The only reason
> we would need to
> memorize arbitrary conventions would be if we ever
> intended to communicate
> clearly with other people.  If we are only concerned
> with understanding
> things ourselves and we never intend to discuss our
> understanding with other
> people, then each of us can adopt whatever
> conventions work for us.  All
> that each of us has to do is be internally
> consistent, and we each can
> figure out how the world works, right?
>
> Don't limit your decision to quit teaching arbitrary
> conventions to just +/-
> signs on work and energy.  Don't memorize any
> arbitrary conventions.  For
> example, don't memorize colors.  Heck, green is just
> an arbitrary name we
> give to the color that is traditionally used for
> signaling cars to proceed
> at a traffic light.  If you personally want to call
> that red, go right
> ahead.  But don't talk to my daughter (who is just
> learning to drive)
> because she is using a different convention for
> colors, and if you tell her
> she should proceed through the intersection when she
> sees the light is red,
> you're going to jeopardize my daughter's life (and
> others as well).  So go
> have whatever color conventions you want, just don't
> talk to my daughter.
>
> All language conventions are arbitrary.  Who needs
> them?  Only those people
> who want to communicate with each other.
>
> Michael D. Edmiston, Ph.D.
> Phone/voice-mail:       419-358-3270
> Professor of Chemistry & Physics        FAX:
>            419-358-3323
> Chairman, Science Department            E-Mail
>            edmiston@bluffton.edu
> Bluffton College
> 280 West College Avenue
> Bluffton, OH 45817


__________________________________________________
Do You Yahoo!?
Find a job, post your resume.
http://careers.yahoo.com