Saturday, August 30, 2014

What Causes Friction?

As an engineering undergrad, I've always wondered, in the back of my mind--what actually causes friction? Curiously, unless my memory is utterly failing me, this topic was not covered, even cursorily, in any of my classes. Friction is introduced as a given, like gravity. Anyway, for some reason--which may have to do with greater free time, as my brood enters Young Adulthood--I finally bothered to research the topic.

It is surprisingly esoteric and unsettled.

What seems like the most obvious idea--microscopic surface irregularities--seems to have been largely discarded (except that surface irregularities seem to be cited as contributing to the adhesion theory). Some of the different theories I came across:

Someday, maybe in the long winter of American Siberia, I will muster the energy and ambition for a Part 2 on this.


  1. Doesn't Rustoleum's NeverWet product explain that water rolls off material without friction (or something like that)?

    1. Huh, that is interesting. Rain-X is a 110, this stuff is a 160+, that is seriously hydrophobic.

      I think fluid-on-solid friction may be a very different beast than what I had in mind in my little inquiry. :)