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Re: [Phys-l] waves on a string





-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
bounces@carnot.physics.buffalo.edu] On Behalf Of John Denker
Sent: Thursday, December 09, 2010 1:52 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] waves on a string

On 12/09/2010 09:00 AM, Carl Mungan wrote:
Anyhow, there's a recent Letter paper by Burko in Eur. J. Phys.
31:L71 (2010) claiming the usual textbook formula for energy of a
string wave is wrong. The gist is that instead of the square of
dy/dx
in the PE term, one should have y * second deriv. of y w.r.t. x.

http://iopscience.iop.org/0143-0807/31/5/L01/

My first remark is that authors who don't number *all* of
their equations should be awarded a dunce cap or some other
badge of shame. It is spectacularly selfish for an author to
number only the equations /he/ wants to refer to. What if
somebody else wants to refer to some of the other equations?

My second remark is that Prof. Burko should proofread his
equations, and/or that IOP should find some reviewers who
actually look at the equations. Some of the equations in
this paper don't pass basic dimensional-analysis checks.

John,
Could you specify two of the equations that don't pass the dimensional
analysis test. I didn't check them all when I read the article but the
ones I did check passed the test.


More importantly: I think the idea of the article is OK as
far as it goes. The author doesn't claim any originality
and cites Morse and Feschbach as a source of the approved
derivation.

I recommend that anybody who is interested in this stuff
(and almost everybody else) should take a look at what
Rayleigh had to say. That was one very smart guy, and
reading his book is always amusing.
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