# Kinetic Friction

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

## Kinetic Friction

Kinetic friction ( $$f_k$$ ) (also called dynamic friction or sliding friction) is the force opposing two objects rubbing together that are moving relative to each other.

### Kinetic Friction formula

$$\large{ f_k = \mu_k F_n }$$

Where:

$$\large{ f_k }$$ = kinetic friction

$$\large{ \mu_k }$$  (Greek symbol mu) = kinetic friction coefficient

$$\large{ F_n }$$ = normal force

Solve for:

$$\large{ \mu _k = \frac {f_k}{F_n} }$$

$$\large{ F_n = \frac {f_k}{\mu_k} }$$