Re: pool table physics

["John S. Denker" <jsd@MONMOUTH.COM>]

At 08:18 AM 4/25/01 -0700, Ben Crowell wrote:

> John, are you agreeing or disagreeing with the
> standard model of friction?

I disagree with the notion that there is any such thing as "the" standard
model of friction.

Depending on context, I can come up with many different models of friction
(some of which are related to others):
 *) Static friction.
 *) Solid-on-solid sliding friction.
 *) Solid-on-solid rolling friction.
 *) Internal damping of an elastic medium under compression.
 *) Internal damping of an elastic medium under shear.
  -- Stokes-law viscous friction (F goes like v).
  -- Ordinary fluid-dynamic friction (F goes like v^2).
 *) Hydroplaning.
 *) et cetera.

Most of these are potentially relevant to pool table physics (as mentioned
in the Subject: line).

> If you disagree with it, then does your
> alternative model of friction make testable
> predictions?

Again, I have no idea what "it" refers to.

Some of the models on the foregoing list make quite accurate predictions,
and have a broad range of applicability.

Some of the models have such a narrow range of applicability that their
real-world usefulness is marginal.

Others barely rise to the level of "rule of thumb" and cannot withstand
theoretical or experimental scrutiny.

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If this isn't clear or detailed enough, please ask a more specific question.