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
A Cellarful of Noise A Cellarful of Noise A Cellarful of Noise is the title of Brian Epstein's 1964 autobiography. His assistant, Derek Taylor, was the ghostwriter of the book, which describes the early days of The Beatles, whom Epstein managed. Epstein asked John Lennon what he thought the book should be called, and Lennon suggested "Queer Jew". Lennon was later quoted as saying that the book should have been titled, "A Cellarful of Boys" in reference to Epstein's homosexuality. In the 1978 film "All You Need is Cash", a book by Leggy Mountbatten—the manager of the Rutles and a parody of Epstein—is titled