Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
bounces@carnot.physics.buffalo.edu] On Behalf Of Carl Mungan
Sent: Thursday, December 09, 2010 6:12 PM
To: phys-l@carnot.physics.buffalo.edu
Subject: Re: [Phys-l] waves on a string
Jeffrey Schnick wrote:
I prefer writing his equation 4 as:
dE = 1/2 [mu dx (2 pi f)^2] y^2 + 1/2 (mu dx) (dy/dt)^2
so it looks more like the energy 1/2 k x^2 + 1/2 m v^2 of a simple
harmonic oscillator but it amounts to the same thing.
Are you really referring to Eq. (4)? In his paper it reads:
dE = 1/2 (mu dx) (dy/dt)^2 - 1/2 (mu dx) v^2 y (d^2y/dx^2).
His first term on the right corresponds to your second term, okay.
But I don't see how his second term corresponds to your first term.
How do you prove that:
(2 pi f)^2 y = - v^2 (d^2y/dx^2) ?
I don't see it. -Carl
--
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/
_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l