[LON-CAPA-users] Should we accept Nm as a unit of torque

Peter Riegler lon-capa-users@mail.lon-capa.org
Wed, 25 Jul 2007 12:54:00 +0200

Hi all,

I am working with a colleague from the mechanical engineering department 
here. As things are, they quite often have problems related to torque 
und use numerical response expecting torque as an answer.

Now, the appropriate SI-unit is N*m which loncapa accepts, of course. 
However, it does not accept Nm. From a syntax point of view, this is 
probably o.k., since I guess the commonly practiced rules are:
o Product of units are to be written as products. The multiplication 
operator can be replaced by an appropriate amount of space.
(So kg*m/s^2, kg m/s^2 will be accepted).
o order of magnitude prefixes are to be attached in front (kg, mg, km, 
MW, kW, etc.)

Now when we come to N*m I bet most of us will violate these rules. 
Please test yourself and write this unit on a piece of paper.

Do you have inserted as many space between N and m as you would have 
between kg and m in kg m/s^2? For all people I have tested the answer is no.

The very intention of this email is to trigger a discussion about 
whether it is suitable to allow Nm as an equivalent to N*m in loncapa.



PS: Thinking about it, Js for angular momenta is a related issue.
Peter Riegler
Fachhochschule Braunschweig/Wolfenbüttel
Salzdahlumer Str. 46/48, 38302 Wolfenbüttel
Tel. +49 5331 939 6314, Fax. +49 5331 939 6002
email: p.riegler@fh-wolfenbuettel.de