What is the coefficient of friction?

friction is a resistance force producing heat generated by the movement of two contact surfaces against each other. It is indirectly a product of one of the four known basic forces. The friction of the system cannot be predetermined strictly from the theoretical first principles. Mathematically, the expression for friction includes one constant that includes all causal factors - coefficient of friction (COF), symbolized by Greek letter, μ. The equation is simply written f _{x = μ x F, where f x defines the form and measure of friction, while F is a perpendicular or "normal" force developed by both surfaces; Individual contributing factors resist complete explanation or quantification. The basic force responsible for most friction is also the one that allows the formation of chemical bonds - electrostatic force. At initial consideration, gravity may seem to be a source of friction, because the force down due to gravity is a source of F.The level of electric charges to avoid "their" together. Such binding is a characteristic of adhesives used to cement two surfaces together.}

that this is the case is well illustrated by a modern polymer, polytetrafluorethylene (PTFE). The best known under her DuPont ™ brand, Teflon®, PTFE shows only a very weakly attractive London dispersion electrostatic forces. This gives the PTFE coefficient of friction between the "top three" known-known 0.05-0.10. If the coefficient of friction were a product of gravity, surface chemistry would be hungry and such substances that would not be as economically important as they are.

There are ways to reduce friction without changing the materials from which the surfaces are made. The friction coefficient for the system can be effectively reduced by providing a thin layer of lubricant. Alternatively, it is often possible to reduce friction by inserting a gas blanket between the surfaces, whatIt reduces the obvious weight of the surface at the top and eliminates production deficiencies such as the roughness of the surface. Change in effective weight reduces normal force, while lack of deficiencies changes friction coefficient; Both mathematically reduce the resulting strength of friction. The engineers used the phenomenon of gas layer to develop for traveling on land and water surfaces.