Mechanical energy swing because of the work done by the pendulum to oppose these non-conservative forces. That the loss of mechanical energy in a system always resulted in an increase of the system's temperature has been known for a long time, but it was the amateur physicist James Prescott Joule who first experimentally demonstrated how a certain amount of work done against friction resulted in a definite quantity of heat which should be conceived as the random motions of the particles that comprise matter. This equivalence between mechanical energy and heat is especially important when considering colliding objects. In an elastic collision,
Dalian Dalian Happy Snow World in Ganjingzi District near the airport. Not many people ride bicycles in Dalian because of the hilly roads. Dalian is also one of the many cities in China where there are few motorcycles, because motorcycle riding on most roads is banned by law. The city has a comprehensive bus system and an efficient metro system. As of November 2015, the Dalian Metro consists of the underground Line 1, Line 2, and the overground Line 12 (Formerly called line R2) and Line 3. New lines and expansion of the metro system are under way. The Dalian Tram