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 to 2009. However, from 2010 to 2015 China reduced energy consumption per unit of GDP by 18%, and CO emissions per unit of GDP by 20%. On a per-capita basis, it was the world's 42nd largest emitter of greenhouse gases in 2014. China is also the world's largest renewable energy producer. China is the largest producer of hydroelectricity, solar power and wind power in the world. Energy policymaking in China is largely decentralised. There has been no Ministry of Energy since it was dissolved in 1993, and it was only in 2002–2003 that serious governmental dialogue on re-centralising energy administration