Mechanical energy nonconservative forces, like frictional forces, will be present, but often they are of negligible values and the mechanical energy's being constant can therefore be a useful approximation. In elastic collisions, the mechanical energy is conserved but in inelastic collisions, some mechanical energy is converted into heat. The equivalence between lost mechanical energy (dissipation) and an increase in temperature was discovered by James Prescott Joule. Many devices are used to convert mechanical energy to or from other forms of energy, e.g. an electric motor converts electrical energy to mechanical energy, an electric generator converts mechanical energy into electrical energy and a
Dalian Polytechnic University economics. Dalian Polytechnic University Dalian Polytechnic University () is a university in Dalian, Liaoning. The school was founded in 1958 in Shenyang as the Shenyang Institute of Light Industry (). In 1970, it was transferred to Dalian, and renamed as the Dalian Institute of Light Industry (). In 2006, it was promoted in 2006 from the rank of institute to the rank of university. It is the only institution of higher education in northeast of China specializing in light industry, food, textiles and art design. There are about 15,000 students on the campus. Subjects taught include engineering, science, arts, management,