Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] g...



On 11/20/2006 01:10 PM, Jeffrey Schnick wrote:

I just went through last months discussion of pseudo forces.

Excellent.

I still have a bunch of questions about this subject.

The
following names were used for the kind of force under consideration
there:

pseudo force
non-inertial force
fictitious force
centrifugal force
Coriolis Force
Virtual force
rot-force (rotational frame force)
inertial force
frame force
d'Alambert force

BTW I think that should be spelled d'Alembert.
http://www-groups.dcs.st-and.ac.uk/~history/Biographies/D'Alembert.html

It is embarrassing to have so much terminology and so little understanding
of what it all means. Ideas are primary; terminology is secondary.
Terminology is important only insofar as it helps us understand and
express the ideas.

John Denker came the closest to saying that a pseudo force is a
gravitational force when he wrote:

* Question: What about gravitation? Is it a pseudo force? Feynman
tip-toes around this one also. He says we must "consider the
possibility" that gravity is a pseudo force ... but never quite
answers his own question.

FWIW I would answer "yes" to the previous question. but if
there are counterarguments I'd be delighted to see them.

Upon reflection, I'm not quite fool enough to rush in where Feynman
feared to tread.

The more I think about it, the more I don't know -- and don't care --
whether gravity should be classified as a pseudo force or not. I
suspect it's the wrong question. Instead we should probably be asking
questions that are more physically meaningful, e.g.
-- is the force proportional to mass?
-- is the interaction screenable?
-- is the interaction blackbox-detectable?
-- does the interaction give rise to /pairs/ of forces, i.e.
action/reaction pairs?

For an explanation of what I mean by this, see
http://www.av8n.com/physics/rotating-frame.htm#sec-fictitious-pseudo