Re: [ARSCLIST] Mostly for laughs

[George Brock-Nannestad <pattac@xxxxxxxx>]

From: Patent Tactics, George Brock-Nannestad

> ----- Original Message ----- 
> From: "George Brock-Nannestad" <pattac@xxxxxxxx>
> > ----- to a later contribution: a centrifugal force can only be generated
> on a
> > body that rotates around an axis (apart from it being virtual). However,
> when
> > a record is played, the stylus does not rotate, so it is not subject to
> any
> > force like that
> >
> I suspect that this may not be entirely correct. The phenomenon we
> refer to as "centrifugal force" is actually the straight-line inertia
> of an object moving in a circular path (or a portion of one).

----- one question, one statement here:

1) which object of those we are considering is moving in that path?

2) the centrifugal force is actually just the inverse of the force required 
to maintain the object in its circular path

 For
> this reason, an object placed on the surface of a rotating phonorecord
> will fly rapidly outward...

----- not until that object has been given the movement, which is tangential

and it would seem that the stylus would
> similarly try to do so, but be prevented in doing so by the
> outside wall of the groove. After all, if you were to place the
> tonearm on an ungrooved disc, would it not fly outward

----- I think that it would depend very much on where the tonearm were 
pivoted, the static compliance of the cantilever, and whether it were an 
offset arm

But at least we may agree that at 78 rpm we have quite a lot of acceleration 
to do good experiments with - the effects will be much enhanced over 33 1/3.

Something for a Science Park perhaps.

Kind regards,


George