C. Northcote Parkinson and journalist Ann Fry (1921–1983), with whom he had two sons and a daughter. In 1958, while still in Singapore, he published his most famous work, "Parkinson's Law", which expanded upon a humorous article that he had published in the "Economist" magazine in November 1955, satirising government bureaucracies. The 120-page book of short studies, published in the United States and then in Britain, was illustrated by Osbert Lancaster and became an instant best seller. It explained the inevitability of bureaucratic expansion, arguing that 'work expands to fill the time available for its completion'. Typical of his satire and cynical humour,
Work (physics) the kinetic energy of the particle by a simple derivation analogous to the equation above. Some authors call this result "work–energy principle", but it is more widely known as the work–energy theorem: The identity formula_54 requires some algebra. From the identity formula_55 and definition formula_56 it follows The remaining part of the above derivation is just simple calculus, same as in the preceding rectilinear case. In particle dynamics, a formula equating work applied to a system to its change in kinetic energy is obtained as a first integral of Newton's second law of motion. It is useful to notice that