Friction

thumb|360px|The blue plate has more friction on the sloped surface than the green one, so slides down slower.

Tribology is the science and engineering of understanding friction, lubrication and wear phenomena for interacting surfaces in relative motion. It is highly interdisciplinary, drawing on many academic fields, including physics, chemistry, materials science, mathematics, biology and engineering. The fundamental objects of study in tribology are tribosystems, which are physical systems of contacting surfaces. Subfields of tribology include biotribology, nanotribology and space tribology. It is also related to other areas such as the coupling of corrosion and tribology in tribocorrosion and the c

Stiction (a portmanteau of the words static and friction) is the force that needs to be overcome to enable relative motion of stationary objects in contact. Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static adhesion. Stiction is a threshold, not a continuous force. However, stiction might also be an illusion made by the rotation of kinetic friction.

particular design of vehicular tire

loss of energy in a pipe through friction along the edge

uneven movement in the form of accelerations and decelerations when objects in contact slide over each other; generating vibrations and mechanical wear

pressure welding using a rotating tool

skin abrasion caused by friction