Sliding (motion)

Sliding is a type of frictional motion between two surfaces in contact. This can be contrasted to rolling motion. Both types of motion may occur in bearings.

The relative motion or tendency toward such motion between two surfaces is resisted by friction. Friction may damage or 'wear' the surfaces in contact. However, wear can be reduced by lubrication. The science and technology of friction, lubrication, and wear is known as tribology

Sliding may occur between two objects of arbitrary shape, whereas rolling friction is the frictional force associated with the rotational movement of a somewhat disclike or other circular object along a surface. Generally the frictional force of rolling friction is less than that associated with sliding kinetic friction. [Benjamin Silliman, "Principles of Physics, Or Natural Philosophy", Ivison, Blakeman, Taylor& company publishers, 710 pages {1871)] Typical values for the coefficient of rolling friction are less than that of sliding friction. [Hans-Jürgen Butt, Karlheinz Graf, Michael Kappl, "Physics and Chemistry of Interfaces", Wiley Publishers, 373 pages, ISBN 3527404139 (2006)] Correspondingly sliding friction typically produces greater sound and thermal bi-products. One of the most common examples of sliding friction is the movement of braking motor vehicle tires on a roadway, a process which generates considerable heat and sound, and is typically taken into account in assessing the magnitude of roadway noise pollution. [ [http://www.springerlink.com/content/x1707075n815g604/] C. Michael Hogan, "Analysis of Highway Noise", Journal of Soil, Air and Water Pollution, Springer Verlag Publishers, Netherlands, Volume 2, Number 3 / September, 1973]

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