Friction is a resistive force that prevents two objects from sliding freely against each other. The coefficient of friction (μ) is a dimensionless number, the ratio of the resistive force of friction (Fr) and by the normal or perpendicular force (Fn) pushing the objects together. It is represented by the equation: μ = Fr / Fn.
It must be noted that friction is proportional to the normal force, rather than the actual weight of the mass in contact;it is invariant to the surface area in contact.
There are different types and values for the coefficient of friction, depending on the type of resistive force. The coefficient of friction can be determined through experiments, such as measuring the force required to overcome friction or measuring the angle at which an object will start to slide off an incline.
Friction, force that opposes the motion of an object when the object is in contact with another object or surface.
Friction depends on this force because increasing the amount of force increases the amount of contact that the object has with the surface at the microscopic level.
In this equation, F is the force of friction, ยต is the coefficient of friction between the object and the surface, and N is the normal force.
Frictional resistance to the relative motion of two solid objects is usually proportional to the force which presses the surfaces together as well as the roughness of the surfaces.
Therefore two coefficients of friction are sometimes quoted for a given pair of surfaces - a coefficient of staticfriction and a coefficent of kinetic friction.
Friction is typically characterized by a coefficient of friction which is the ratio of the frictional resistance force to the normal force which presses the surfaces together.
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