This question already has an answer here:

The simplest answer is that the protuberances on the rough surfaces have inelastic collisions on each other and thus have a macroscopic tendency to impede motion.

Is there any more comprehensive and complete theory about how friction rises?

Is f=μN a theoretical conclusion or an approximate experimental result?

Why is the magnitude of friction LINEARLY proportional to the normal force exerted on the contact surface?


marked as duplicate by John Rennie, valerio, Jon Custer, Chris, sammy gerbil Feb 5 '18 at 14:54

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  • $\begingroup$ Ultimately it's all about electrodynamics. $\endgroup$ – Rexcirus Feb 4 '18 at 15:46
  • $\begingroup$ $F=\mu N$ is purely empirical. $\endgroup$ – valerio Feb 4 '18 at 15:54
  • $\begingroup$ if you google "microscopic view of friction" a number of references come up $\endgroup$ – anna v Feb 4 '18 at 17:57

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