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Re: Centrifugal force



At 8:33 -0500 11/17/03, Rick Tarara wrote:

In fact, many of us also object to the term 'centripetal' force on the
pedagogical grounds that students come to think that there is such a thing
in nature called the centripetal force. You will get free-body diagrams
with a force labeled Centripetal Force. I try to talk about the centripetal
acceleration and the need to identify the force or forces that produce the
centripetal acceleration.

Hear, hear! It is a common misconception that there is a "centripetal
force" that must be included in a force diagram, and it is a huge
source of confusion. We are much better off *never* using the term
"centripetal force," and limiting the word centripetal to
"centripetal acceleration." I have even seen seasoned high school
physics teachers get bollixed by this. They know what the answer is
supposed to be for, say, the force on an object at the top of a
vertical circle, and then when they draw the force diagram, they
include a centripetal force term and when their answer is nonsense,
they recognize that it is clearly a wrong answer, but have no idea
why it is wrong.

I prefer to talk only about the "net force" on an object and then
point out that this corresponds to the mass times the centripetal
acceleration (in the case of UCM, of course).

The idea that centrifugal force "doesn't exist" is also widespread
among HS physics teachers. That's probably better than having them
believe that it is a real force, even in inertial reference frames,
but their dogmatic assertion that it doesn't exist indicates to me
that there are a lot of HS physics teachers out there who harbor some
serious misconceptions about some fundamental aspects of Newtonian
physics.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

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