Re: centrifugal force (cont)

["RAUBER, JOEL" <JOEL_RAUBER@SDSTATE.EDU>]

And a related question: you are in a black box observing the motion of a
ball.  You observe that it is accelerating.  Is there a force acting on it?

The black box prevents you from observing the universe outside of the box,
but does not necessarily shield the contents of the blackbox from influences
originating from outside the blackbox.

Joel R.

> -----Original Message-----
> From: Robert Cohen [mailto:Robert.Cohen@PO-BOX.ESU.EDU]
> Sent: Friday, December 13, 2002 8:48 AM
> To: PHYS-L@lists.nau.edu
> Subject: Re: centrifugal force (cont)
>
>
> My brother and I are on a rotating platform (like the kind at
> playgrounds).  While it is spinning, I push my brother off by
> exerting a force on him directed away from the center.  Is
> this a real centrifugal force?
>
> ____________________________________________
> Robert Cohen; rcohen@po-box.esu.edu; 570-422-3428;
> http://www.esu.edu/~bbq
> Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301
>
> > -----Original Message-----
> > From: Bob Sciamanda [mailto:trebor@VELOCITY.NET]
> > Sent: Thursday, December 12, 2002 8:41 PM
> >
> > It comes down to one of two consistent positions:
> > 1) The Newtonian model, in which a force is a frame invariant
> > interaction
> > between objects.  The net force on an object is correlated to its
> > acceleration as viewed from an inertial frame.  Non inertial
> > observers will
> > see "inertial effects" which, because of their own (the observer's)
> > acceleration, will mimic the accelerations produced by real forces.
> >
> > 2) The Einsteinian model, in which the concepts of both
> > gravitational and
> > inertial forces are replaced by geodesic travel through
> non-Euclidean
> > space-time.  The force concept is left to apply only to
> > non-gravitational/inertial effects (eg. electromagnetic
> > interactions), which
> > are not (yet?) accommodated by this model.
> >
> > The concept "real centrifugal force" has no place in either
> > scheme.  It
> > adopts the Newtonian word "force", but violates the
> Newtonian concept
> > "force".  It is born of a subconscious desire to invoke a
> > real force to
> > account for any and all accelerations - observed by any and
> > all observers.
> > It makes frame dependent acceleration (as viewed by ANYONE)
> > the definition
> > of  force.  This is neither Newtonian nor Einsteinian.  It
> > should drive a
> > thinking student wild!