Re: [ATM] Use of bearings in (static) mirror cells

["matt" <electro_optic@bellsouth.net>]

those are not strictly speaking solid sliding friction. Our common
perception of what's solid and what's sliding friciton is not necessarily
correct .

The examples you quoted are perhaps sliding objects but not  rigid bodies
and not only sliding friction is taking place.

The friction coefficient in mechanics is defined for rigid bodies and for
strictly friction. No elastic deformation, no plastic or thermoplastic
deformation, no vibrations, wet, viscous, Reynolds numbers, etc etc.

Once we start discussing these subjects, we could as well turn this into a
tribology or fluid dynamics mailing list , these subjects are huge .

best regards,
matt tudor

-----Original Message-----
From: Mark Holm <mdholm@telerama.com>
To: atm@atmlist.net <atm@atmlist.net>
Date: Thursday, April 21, 2005 7:39 PM
Subject: Re: [ATM] Use of bearings in (static) mirror cells


>Certain combinations of materials do have velocity dependent friction.
>I strongly recommend an article in the October 2003 Sky and Telescope,
>pages 122-126, by Martin Lewis.  Martin performed measurements of
>sliding friction for several combinations of materials over a range of
>velocities.  His conclusions are too detailed to summarize briefly here.
>  If you are going to build a sliding bearing telescope (similar or
>identical to the "classical" Dobsonian design, you really should read
>this article.
>
>If you can't get it at your public library, you can purchase it on line
>at S&T's web site.
>
>--
>Mark Holm
>mdholm@telerama.com
>
>_______________________________________________
>ATM mailing list http://www.atmlist.net/
>

_______________________________________________
ATM mailing list http://www.atmlist.net/