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
Feathers: The Evolution of a Natural Miracle Feathers: The Evolution of a Natural Miracle Feathers: The Evolution of a Natural Miracle is a 2011 natural history book by American conservation biologist Thor Hanson. Published by Basic Books and written for general audiences, the book discusses the significance of feathers, their evolution, and their history both in nature and in use by humans. "Feathers" is divided into five parts. In "Evolution", Hanson discusses the scientific debate over how feathers evolved, interviewing ornithologists Richard Prum and Alan Feduccia, as well as paleontologist Xing Xu. In "Fluff", Hanson discusses how feathers play a role in regulating a bird's body temperature