- #1

FranzDiCoccio

- 342

- 41

The question is: can a coefficient of friction (static) be larger than one?

I see confusing replies. Someone talks about glue, but I'm not convinced about that. It's a bit like wondering about the coefficient of friction of a wooden plank nailed to a wall.

I like the "micro hills" explanation by pixel01, and the table tennis video by rcgldr.

Actually, whenever something won't slide down a plane inclined at an angle larger than 45° it should be

[itex]\mu_s>1[/itex], right?

However I'm not sure about the table tennis rubber. To what extent the surface is really a plane? If it has grooves the object can hang onto those "mechanically" (I mean, at the macroscopic level).

Again, it is a bit like saying that the coefficient of friction between ice crampons and ice is very high.

I think that [itex]\mu_s[/itex] can be larger than one, but I'd like a more precise answer... I'm not sure there is one though. I guess that the surfaces one considers should not be too irregular, but I don't know whether a quantitative rule exists. When is a micro hill really micro? When it is small compared to the area of the sliding surfaces?

Thanks