Friction and Friction Coefficients Engineering
The friction force is the force exerted by a surface when an object moves across it or makes an effort to move across it.. The frictional force can be expressed as. F f = μ N (1). where. F f = frictional force (N, lb). μ = static (μ s) or kinetic (μ k) frictional coefficient. N = normal force between the surfaces (N, lb) There are at least two types of friction forces