Re: [ARSCLIST] Mostly for laughs

[Don Cox <doncox@xxxxxxxxxxxxxx>]

Hello Mike

On 23/10/06, Mike Richter wrote:
> Steven C. Barr(x) wrote:
>> ----- 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). For
>> this reason, an object placed on the surface of a rotating
>> phonorecord will fly rapidly outward...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>
> 
> To some it may be clearer to say that what's called "centrifugal
> force" is the reaction to the centripetal acceleration needed to keep
> the object moving on a circular path.
> 
> Or maybe that's cloudier still.

There may well be a "centrifugal force" acting on the molecules of the
disc itself, but this has nothing to do with skating, which is caused by
the geometry of the arm.

Regards
-- 
Don Cox
doncox@xxxxxxxxxxxxxx