. . . . . . . "http://dbpedia.org/resource/Friction"^^ . . . . . . . "Friction"@en . . . . . "http://wiki.answers.com/Q/What_is_the_symbol_of_friction"^^ . . . "http://en.wikipedia.org/wiki/Friction"^^ . . . "\"Friction\" is the force of two surfaces In contact, or the force of a medium acting on a moving object (that is air on an aircraft). When contacting surfaces move relative to each other, the friction between the two objects converts kinetic energy into thermal energy." . . . .