# Static Friction Coefficient

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Static friction coefficient, abbreviated as $$\mu_s$$ (Greek symbol mu), a dimensionless number, also called coefficient of static friction, is the amount of force that resists motion that is on the verge of motion.

## Static friction coefficient formula

 $$\large{ \mu_s = \frac {f_s}{F_n} }$$

### Where:

 Units English Metric $$\large{ \mu_s }$$  (Greek symbol mu) = static friction coefficient $$\large{ dimensionless }$$ $$\large{ F_n }$$ = normal force $$\large{ lbf }$$ $$\large{N}$$ $$\large{ f_s }$$ = static friction $$\large{ lbf }$$ $$\large{N}$$