Re: test problem

[Brian Whatcott <inet@INTELLISYS.NET>]

I expect Bob's concerns have been quenched by the notes from
John M., but it would be churlish not to mention the two physical features
that need attention when framing a puzzle concerning the prototypical
illustration of the differential equation of harmonic motion.

1) In a loose wound coil spring, the coils can close up if the initial
amplitude is
greater than the equilibrium extension of the mass to be oscillated.
Still, the spring rate can be established with a single data pair of deflection
 for a given weight.

2) In a close wound coil spring, there is likely an initial force required
to provide
 the initial infinitesimal deflection.
In this case, the procedure provided by Rick (which provides two data pairs
for
weight & deflection in effect) is needed to establish the spring rate.

Brian W


At 10:48 PM 12/4/01, you wrote:
> Brian objected:
> > No, the questions are unreasonable. If the extra downward displacement is
> > greater than the equilibrium displacement, then the possibility of coil
> > binding is not excluded on the upward rebound.
>
> I don't understand this objection - I would think coil "binding" (?) is a
> function of other things having to do with the coil design and structure. As
> g is made to go to zero (go to different planets, or just turn down gravity)
> "the extra downward displacement" becomes infinitely "greater than the
> equilibrium displacement". You imply this worsens the situation!
>
> >     For this same reason, the spring constant is not determined by only
> the
> > force required for a specified displacement.
>
> I understand this statement even less.  Surely the static k is still
> "determined by only the force required for a specified displacement".  Do
> you refer to some "dynamic" k associated with the binding during
> oscillation?
>
>
>
> Bob Sciamanda (W3NLV)
> Physics, Edinboro Univ of PA (em)
> trebor@velocity.net
> www.velocity.net/~trebor

Brian Whatcott
  Altus OK                      Eureka!