# How to develop the static and kinetic friction formula? [duplicate]

How do you end up with the formula for Amontons' first law of friction? ($F_s = \mu_s \times N$) or ($F_k = \mu_k \times N$). I know how to use the formula. Now I need to know how to get to it.

• Welcome to Physics Stack Exchange. In order for someone to be able to answer this question, that person would first need to know what the symbols in your equation mean. – DanielSank Oct 8 '15 at 2:57