Re: Torque or moment about a joint

[Robert Soutas-Little]

I have tried to resist weighing in on what is becoming a useless
conversation. A moment is the turning effect of a force about a
particular point in space and is defined by the vector equation r x F =
M. The term moment is the preferred terminology for the turning effect
of a force. The term torque is used interchangeably with moment in
many applications, but is generally associated with twisting. This is
particularly true is the study of elasticity or mechanics of deformable
materials when torsion of shafts or Saint-Venant torsion theory and
where moment is generally used when referring to bending of beams by
transverse loading. ( See Elasticity; Robert Soutas-Little, Dover;,1999
or Theory of Elasticity; Timoshenko and Gere). I could list dozens
more references but to no point.

People working in the general area of theoretical mechanics have a
special obligation to people who are using their theories is such areas
of biomechanics to be careful not to add confusion to the terminology.
Something that I have learned after 55 years of research in both
elasticity and biomechanics.

I hope this is of some help in this discussion.

Thanks,
Robert Soutas-Little
Professor Emeritus, Michigan State University

On Wednesday, November 7, 2007, at 01:53 PM, Dr. Hamid Rassoulian
wrote:

> Hi again,
>
> Since I am tempted to make a more daring contribution would you
> consider
> having acquired a puncture whilst driving and you want to change the
> wheel.
> Also consider that you have at your disposal one of those general
> purpose
> spanners that look like a + with a socket at each end. So to take
> off the
> bolts of the wheel you would apply the spanner to the bolt and with
> both
> hands (one on either side, one pushing down and one pushing up) you
> would
> apply a "twisting" force or torque to the bolt. However, if you were
> to use
> one hand only you would be applying a turning moment to the bolt.
>
> thanks
>
> Hamid
>
>
> --
> Dr. H Rassoulian BSc, MSc, PhD, CEng, FIMechE
> Clinical Scientist
> Dept. Medical Physics & Bioengineering
> Southampton General Hospital
> Tremona Rd.
> Southampton SO16 6YD
>
> Tel: +44 (0)23 80 79 69 45
> Fax: +44 (0)23 80 79 41 17
> Alternative Email:
> Hamid.Rassoulian@suht.swest.nhs.uk
>
>
> =================================================
> PLEASE DO NOT PRINT UNLESS ON Recycled unbleached paper
> =================================================
>
>
>
>
>
> Quoting Dale Cannavan :
>
>> Dear Subscribers,
>>
>>
>>
>> Can anyone explain / define the differences in the meaning of Torque
>> and
>> Moment. It is often stated that they are synonymous; however, some
>> suggest they are different.
>>
>>
>>
>> Thanks for your time,
>>
>>
>>
>> Dale Cannavan
>>
>> Ph.D. Candidate
>>
>> Centre for Sports Medicine and Human Performance
>>
>> Department of Sports Sciences
>>
>> Brunel University
>>
>> West London
>>
>>
>>
>>
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>
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>
Robert Soutas-Little PhD
Professor Emeritus of Engineering Mechanics
Michigan State University
P.O. Box 1143
Leland, Mi 49654
Tel: (231) 256-7646 FAX: (231) 256-7708

FedEx and UPS address:
187 S. Highland Dr.
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