Friction

[S. Brady]

On Wed, 2 Aug 1995 PianoBook@aol.com wrote:

> >This notion that friction is related to the contact surface
> >area is a common mistake.
> >Friction is independent of the contact surface area.
>
> I'm surprised to hear that friction is independent of the contact area.
>  Could you please explain why this should be so, counter-intuitively?
>
> Larry Fine

      Dan Squire's statement should have read something more like:
"*Static* friction is *approximately* independent of area of contact."
This is a true statement. I think of it as being true because as the area
of contact increases, assuming the normal force remains constant, the
amount of pressure per unit area decreases. So, the static friction
remains the same. It's important, however, to remember that laws which
apply to a brick on a table may not be the same laws which govern a
complex and dynamic scenario such as a piano action in motion. To assume
that they do seems incredibly naive to me.


Steve Brady, RPT        "The most expert and rapid tuners are...
University of Washington       possessed of a highly excitable,
sbrady@u.washington.edu        nervous, and emotional temperament,
                         verging on the border of insanity at times."
                              -Daniel Spillane, The Tuner's Guide