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]

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/