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Re: [Phys-l] pseudo-force



On 10/26/2006 10:52 AM, David Bowman wrote:

I think they mean any tendency to cause an acceleration w.r.t. a
non-inertial reference frame that has no agent responsible for
producing it a la Newton's 3rd law and which is directly proportional
to an object experiencing it's mass, and which disappears in an
inertial refernce frame.


I have no objections to that definition, but here are some remarks
and questions.

Remark: Feynman (volume I chapter 12 section 5, entitled "pseudo
forces") tip-toed around the issue of /defining/ a pseudo force,
but gave some examples.

-- there is a term in the equation of motion that appears when
the frame of reference is accelerating in a straight line.

-- there is a corresponding term for rotating frames.

Everything is consistent to this point.

* Question: What about the Coriolis effect? Is it properly called a
pseudo force? The Coriolis effect is "proportional to the object's mass"
... but also proportional to its velocity.

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

* 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.

* Question: Are there any textbooks that have anything to contribute to
this discussion? Feynman I-12-5 is (by Feynman standards anyway) rather
weak, but it's all I remember seeing on the subject, without having
attempted a systematic review of the literature. AFAICT Halliday & Resnick
avoid the subject (and the term) entirely, as do Sears, Zemansky, & Young.