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Re: The old centrifugal force



At 04:35 AM 11/15/2003, Ludwik, you wrote:

Do you know how the centripetal force can be
explained in a stationary (laboratory) frame? If you
do then please share your logical sequence. It is
not hard to explain that a centripetal force, of some
kind, must exist to account for the centripetal (v^2/r)
acceleration. But it is hard to identify that force in
some specific situations, for example, when an
object is sliding vertically inside a looping track.
If it is not an N3 reaction force then what is it?
Ludwik Kowalski

Here is a concrete example which may be helpful.

From model train set parts, I build two concentric circles of
track in proximity.

I next make a special truck, which carries rollers which
permit easy movement of cargo in the transverse direction.

I now gingerly place a block on the cargo truck on the inner
track, and start the goods train into movement.

As the train moves in a circle, the block rolls off the truck,
in its attempt to continue tangentially.

Now, I set a second train on the outer track.
This one has a truck with transverse buffer springs.
I align the springs opposite the inner truck on which the
block has been replaced.

I now set both trains in motion. The block on the inner
truck begins to roll off sidewards, as before.

Now it touches and compresses the buffer springs on the
outer truck. The compression of these springs is a measure of
the force needed to hold the block on its inwards acceleration:
This force is passed by the outer truck to its wheel flanges
in the usual way. Lets call it an effective centripetal force.

I see it, and I am stationary in the lab frame.
This force is only available to masses which are accelerating.


Brian Whatcott Altus OK Eureka!