# Normal Force

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Normal force, abbrevation is $$F_n$$, is always perpendicular to the surface it contacts and equal to the weight of the object. Unless there is another external force pushing the object into the contact surface there will be no normal force.

## Normal force formulas

 $$\large{ F_n = \frac { f_k } { \mu_k} }$$ (kinetic friction) $$\large{ F_n = \frac { f_s } { \mu_s} }$$ (static friction)

### Where:

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