Friction Coefficient

Friction coefficient, abbreviated as \(\mu\), also called coefficient of friction, a dimensionless number, is a measure of the force required to move one surface over another, relative to the pressure holding the surfaces together.  It is defined as the ratio of the frictional force between two surfaces to the normal force pressing the surfaces together.  In other words, it is the amount of force required to slide one surface over another per unit of force holding them together.  The friction coefficient depends on various factors, including the surface roughness, the materials of the surfaces, and the contact pressure.

Friction Coefficient Formula
\( \mu \;=\; F_a \;/\; F_n  \)     (Friction Coefficient) \(  F_a \;=\; \mu \; F_n  \) \(  F_n \;=\; F_a \;/\; \mu  \)
Symbol	English	Metric
\( \mu \)  (Greek symbol mu) = Friction Coefficient	\(dimensionless \)	\(dimensionless \)
\( F_a \) = Applied Force	\( lbf \)	\(N\)
\( F_n \) = Normal Force	\( lbf \)	\(N\)

• See Articles  -  Friction Coefficient of Materials

The friction coefficient is important in many areas of science and engineering, including mechanics, materials science, and tribology (the study of friction, wear, and lubrication).  By understanding the friction coefficient of a system, researchers can better predict and control its behavior, such as the amount of force required to move one surface over another, the wear and tear on the surfaces, and the efficiency of energy transfer in the system.