In physics, friction is the effect of rubbing, or the resistance which a moving body meets with from the surface on which it moves. Friction arises from the roughness of the surface of the body moved on and that of the moving body. No such thing can be found as perfect smoothness of surface in bodies. In every case there is, to a less or greater extent, a roughness or unevenness of the parts of tlie surface, arising from peculiar texture, porosity, and other causes, and therefore when two surfaces come together the prominent parts of the one fall into the cavities of the other. This tends to prevent or retard motion, for in dragging the one body over the other an exertion must be used to lift the prominences over the parts which oppose them. What is called the coefficient of friction for any two surfaces is the ratio that subsists between the force necessary to move one of these surfaces horizontally over the other, and the pressure between the two surfaces. Thus the coefficient of friction for oak and cast-iron is 38 : 100, or .38. Friction plays a most important part in nature and art; for instance, without friction threads could not be made nor textile fabrics manufactured. Research Friction
Abbreviations
SciTech
Research Friction