nberme52

12-12-2000, 12:20 AM

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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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

---------------------------------------------------------------

To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl

For information and archives: http://isb.ri.ccf.org/biomch-l

---------------------------------------------------------------

---------------------------------------------------------------

To unsubscribe send SIGNOFF BIOMCH-L to LISTSERV@nic.surfnet.nl

For information and archives: http://isb.ri.ccf.org/biomch-l

---------------------------------------------------------------