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
Dandong–Dalian intercity railway and a half years and was started on 17 March 2010. It started operation on 17 December 2015. Dandong–Dalian intercity railway The Dandong–Dalian intercity railway () is a high-speed line operated by China Railway High-speed within the Liaodong Peninsula of Liaoning province, connecting the coastal cities of Dandong and Dalian. Dandong–Dalian intercity railway is broken down into three segments: Dandong–Zhuanghe, Zhuanghe–Dengshahe, and Dengshahe–Dalian. It will have a total length of about , of which will be in the Dandong prefectural area, will be in the Dalian region. The total investment is estimated to be about 14.7 billion yuan with a