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 published by the National Audubon Society. "Feathers" is Hanson's second book, after "The Impenetrable Forest: My Gorilla Years in Uganda" (2008). Following a preface and introduction, "Feathers" is divided into five main parts: "Evolution" discusses the evolutionary history of feathers, "Fluff" explains the role of feathers in regulating body temperature, "Flight" discusses the origin of avian flight as well as its impact on human aviation, "Fancy" discusses the role of feathers in sexual selection and human fashion, and "Function" discusses the continuing evolution of feathers in both nature and human usage. "Feathers" begins with the 1861 discovery of the first