Displacement and position (was: displacement and graphs)

["RAUBER, JOEL" <JOEL_RAUBER@SDSTATE.EDU>]

I'm simply going to have to disagree.

John D's "displacement", "displacement generally means position relative to
some arbitrary reference." is the less-general case as it requires reference
to an origin, i.e. it is displacement from the origin, a particular point,
my and the quoted reference's displacement requires no such particular
point, although it is covenient to use such a fiduciary point for
calculational purposes.

Or to say it slightly differently: What John D calls displacement is the
special case of displacement from the origin. (and hence less-general).
John D's displacement is what I call "position", which I define to be
displacement from the origin.

When I look at Feynman page 47-4, Feynman's use of the word "displacement"
appearing in figure 47-3 as well as in the verbiage and math of the text
appears to me to match my definition and use of the word displacement.

And to further name-drop, (not really a valid method in scientific
discussions other than to point out popular usage and definitions of terms)
the 9th edition of Sears and Zemansky "University Physics" page 10 follows
my usage.  (Note: the 9th edition no longer has the names Sears and Zemansky
on it, which I consider a bit of sacriledge on the part of the publishers,
but that is another discussion.)

And to quote John D:

"Citing examples of less-general usages is not going to prove anything."

> -----Original Message-----
> From: John S. Denker [mailto:jsd@MONMOUTH.COM]
> Sent: Wednesday, October 10, 2001 8:06 AM
> To: PHYS-L@lists.nau.edu
> Subject: Re: displacement and graphs
>
>
> I wrote:
> > > As mentioned previously, displacement generally means
> > > position relative to some arbitrary reference.
>
> Then at 07:45 AM 10/10/01 -0500, RAUBER, JOEL wrote:
>
> > A quick cursory glance at the four introductory texts in
> arms reach define
> > displacement not as above, but rather as r_2 - r_1, i.e. as change in
> > position.
> >
> > Tipler page 19
> > Halliday and Resnick "Physics" page 37
> > Crummett & Western page 41
> > Lea & Burke page 32
>
> Those represent a less-general usage, a special case.  There's nothing
> wrong with special cases, so long as they are recognized as such.
>
> I stand by what I wrote.  The first two books within the
> reach of *my* arms
> agree with my more-general usage:
> *) _The Feynman Lectures on Physics_ volume I page 47-4 et seq.
> *) Sears, _Principles of Physics_ page 481 et seq.
>
> This is general case.  Citing examples of less-general usages
> is not going
> to prove anything.