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Mccay Mike
12-12-2000, 03:30 AM
More centrifugal force stuff:

An object that is in circular motion is NOT in
equilibrium! It has the centripetal force acting on
it with no need to have another force to balance.
Accelerations act to change the velocity. Because
velocity is a vector (which has magnitude and
direction), acceleration can either change the
magnitude of velocity (speed), or the direction of
velocity, or some combination of the two. Circular
motion is a case where the speed remains unchanged,
but direction is constantly changing because of the
centripetal force. So even though an object in
circular motion is not changing speed doesn't mean
that it is not accelerating - in fact it is
accelerating and needs to have a non-zero net force
acting on it in order to do so.

--- Necip Berme wrote:
> Here is more on centrifugal force!!
>
> In mechanics, when all forces and moments acting on
> a body are shown (i.e.
> the "free body diagram"), it is customary to use
> "inertia forces" to ensure
> equilibrium. An inertia force is a force equal and
> opposite to the net
> acceleration multiplied by the mass of the body.
> That is, it is equal and
> opposite to the external force acting on the body.
> For an object to move on
> a curved path, an acceleration directed towards the
> center of rotation is
> necessary (otherwise the object will maintain a
> straight-line path). This
> acceleration is one of the "normal" components of
> acceleration (the other
> normal component is the "coriolis" acceleration).
> The "centrifugal force" is
> the inertia force corresponding to this normal
> component of acceleration. It
> may be an imaginary force, if you like, - but an
> absolutely necessary one if
> the equilibrium equations are to be valid.
>
> Necip Berme, Ph.D.
> Professor, Mechanical Engineering
> The Ohio State University
> 206 W 18th Avenue
> Columbus OH 43210
>
> Phone: 614 292-0859
> Fax: 614 430-5425
> E-mail: berme.1@osu.edu
>
>
>
>
>
>
> ----- Original Message -----
> From: Gary Christopher
> To:
> Sent: Monday, December 11, 2000 9:31 AM
> Subject: Centrifugal Force
>
>
> In teaching and studying Biomechanics I have used
> three textbooks, all of
> which mention, and then try to justify, the
> existence of centrifugal force.
> Yet if I check my physics book it tells me flat out
> that there is no such
> thing. What is the biomechanics community's take on
> the subject?
>
> Just so you know my personal leanings, I don't put
> any stock in its
> existence, so I'm left trying to convince my
> students why I'm right and
> their textbook is wrong.
>
> If we all believe Newton's Second Law of Motion, we
> should be able to easily
> determine that the so-called "centrifugal force" is,
> in fact, fantasy. If we
> believe Newton's Second Law, we should scoff at the
> notion of a force that
> does not have an accompanying acceleration.
>
> As is customary, I will post a summary of responses.
> Please reply directly
> to my email: gac6@email.byu.edu
>
> Gary Christopher
> Brigham Young University
>
>
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