Re: work done by friction

[Jim Green <JMGreen@SISNA.COM>]

> The vast majority of cases of frictional forces given in textbooks
> involve bodies losing kinetic energy as they slide along rough
> surfaces.  In these cases (of dynamic friction) the mechanism is such
> that the frictional forces are localized, that is, there is no
> displacement of the points of application and NO work is done by the
> frictional force.

Brian, et al:

I am still back here and an wondering if it is really the case "that is,
there is no
> displacement of the points of application and NO work is done by the
> frictional force.

Can someone please amplify this concept -- an perhaps give a convincing
example or two???

I have always pictured the case that there _is_ relative motion during the
passing of bumps or crags or during the application of local coulomb forces.

Could some expert on the mechanism of friction enlighten us/me?

TX

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen