Re: SLINKY

[John Denker <jsd@MONMOUTH.COM>]

At 11:47 AM 1/22/00 -0500, Ludwik Kowalski wrote:
> The speed of a small transverse disturbance along a coiled
> spring is v=sqr(T/mu), where T is the constant tension and
> mu is the linear mass density.

Reeeeally?  I would have thought that was the speed for waves on a *string*
not a spring.  That is, that formula neglects stiffness.  It is easy to
have a coiled spring with zero or even negative tension, and the speed of
transverse waves does not become zero or imaginary.

>  What is the speed of a small
> longitudinal disturbance along the same spring?

What's wrong with
  1 / sqrt(rho s)
where
  rho = density per unit length [kg / m] and
  s = compliance per unit length [1 / nt]

which can be obtained by using elementary kinematics or indeed by using
dimensional analysis.