Re: terminology: period vs. wavelength

[Bernard Cleyet <anngeorg@PACBELL.NET>]

And I suppose your math prof. would say the period of a pendulum is the
distance traveled by the bob in one cycle?

bc
 

"John S. Denker" wrote:

At 01:14 PM 6/29/01 -0400, Michael Edmiston wrote:

>The dictionaries are on my side, they specifically say the root of period is
>periodus and this specifically refers to a time interval.

Not all dictionaries say so.
   http://216.156.253.178/CENTURY/05/index05.djvu?djvuopts&page=844

Before there was Latin _periodus_ there was Greek
         _periodos_    "circuit"
from
         _peri_   "around"
         _odos_   "way"     (same root as "odometer")
giving no reason to restrict the concept to temporal periods.

>But I am completely outnumbered by current-day math professors who are
>teaching scads of students that period does not need to be a time interval.

I think most physicists would be perfectly comfortable saying that in a
crystal lattice, the atomic positions are given by a periodic function of X
and Y.

>Nonetheless, I still expect students to work problems in context.  If I
>ask students for the wavelength of a sound wave I expect them to report a
>length,

OK.

>and if I ask for the period of a sound wave I expect them to report a time.

Not so clear.

>However, it is certainly an eye-opener to talk to math professors and
>realize how much of the terminology used in math classes these days is
>stuff I never
>heard of, or stuff that is different than the way I learned it and teach it.

To my ears, in this context wavelength is a _more specific_ term than
period, equivalent to "spatial period".  But that doesn't make it wrong to
call it a period -- just as it is usually not wrong to call a lawn a lawn,
without specifying what species of grass it is.