# How to find the coefficient of friction?

Friction is a rather complicated process of worksolids in the process of relative motion or while the body moves in liquid or gaseous form. How to find the friction coefficient? It directly depends on the material of the surfaces of friction, the quality of processing and a huge number of other factors. Very often in physics problems it is necessary to learn how to find the coefficient of sliding friction ?. We will try to answer this question.

- If the body moves along the horizontal partsurface of another body, then the reaction of the support is directed perpendicularly to the given slip plane. According to the Coulomb law, F = kN, where N is the reaction force of the support, and k is the coefficient of friction. We transform this formula into N = Fraction = mg, since the reaction of the support is directed strictly vertically.
- Also, the coefficient of friction can be calculated fromthe following formula k = Ftr / N = Ftr / mg. Here we need to know the sliding friction force. It can be found if we know the acceleration a. Having slightly transformed the formula, we obtain k = (F-ma) / N. From this it follows that the coefficient of friction is a dimensionless quantity.
- Another way to find the coefficient of frictionis as follows. If the body slides along an inclined plane, for example, from a block, then the angle of inclination of the plane is assumed to be φ. N is the reaction force of the support, which is directed perpendicular to the indicated plane. The equation of motion of the body, according to Newton's law, is written as follows: N = mg * cosφ, mg * sinφ-Ftr = mg * sinφ-kN = ma. We transform this equation and get: g * sinφ-kg * cosφ = a. It now becomes clear that k = (g * sinφ-a) / (g * cosφ).
- Having considered the well-known special caseslipping of the object along an inclined plane in which a = 0 or, in other words, the body moves rectilinearly and uniformly. In this case, the equation of motion is g * sinφ-kg * cosφ = 0. We express the coefficient k = tgφ. From this it is clear that in order to find the slip coefficient, it is enough to know the slope of the slope.

Now you can easily tell everyone how to find the coefficient of friction in several ways.