Friction

 

Friction definition summary

 

Friction: Friction resists the relative motion of contacting surfaces. The friction force always opposes the direction of intended relative motion between the two contacting surfaces.

 

Coulomb Friction: Coulomb friction can be viewed as the tangential component of the contact force which is generated when two dry surfaces slide or are intending to slide relative to each other. The Coulomb friction force can be categorized as being static or kinetic.

 

Static Friction Force: The friction force that occurs under static conditions (i.e. no relative motion between the contacting surfaces). The static friction force is determined by applying the equilibrium equations to the system.

 

Maximum Static Friction Force: The largest static friction force that can occur before relative motion between the contacting surfaces begins. The maximum static friction force is determined by applying the equation F_fs,max = μ_sN, where N is the normal force between the contacting surfaces and μ_s is the static friction coefficient.

 

Kinetic Friction Force: The friction force that occurs when there is relative motion between the contacting surfaces. The kinetic friction force is determined by applying the equation F_k = μ_kN, where N is the normal force between the contacting surfaces and μ_k is the kinetic friction coefficient.