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,
Energy policy of China has the goal of achieving an integrated nationwide grid in the period between 2015 and 2020. In 2015, China generated 73% of its electricity from coal-fired power stations, which has been dropping from a peak of 81% in 2007. China is the world's leading renewable energy producer, with an installed capacity of 152 GW. China has been investing heavily in the renewable energy field in recent years. In 2007, the total renewable energy investment was $12 billion USD, second only to Germany. In 2012, China invested $65.1 billion USD in clean energy (20% more than in 2011), fully 30% of