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 "as synthesis goes, it is gracious, funny, persuasive and wide ranging." Peter Forbes, in a review published by "The Guardian", stated that Hanson's "enthusiasm is infectious", particularly for a topic Forbes found "alluring". "The Economist" published a review which also described Hanson as having "infectious enthusiasm" and stated, "Mr Hanson's unpretentious style makes what is essentially an excellent scientific work into an enjoyable read for the ignorant and uninitiated." Irene Wanner, in a review published by "The Seattle Times", highlighted Hanson's analogies, calling them "apt" and helping to "simplify complex concepts". "Kirkus Reviews" described "Feathers" as a "delightful ramble through