^Coefficient of friction 

^Coefficient of friction 

1. Coefficient of friction is abbreviated by the symbol μ.
2. It is a unit less dimensionless constant.
3. Its value decides the extent of roughness or smoothness of two contact surfaces.
4. Its value is low for smooth, wet & moving surfaces, and high for rough, dry & static surfaces.
5. Generally μ < 1 but can be > 1 also. Coefficients of static (μ_s) & kinetic friction (μ_k) are experimentally obtained and depend entirely on the two interacting surfaces.
6. It is independent of normal reaction & frictional force.