 Advanced Classical Mechanics by Iain W. Stewart

Authored lecture notes, MIT 8.09 and 8.309, title page naming Iain W. Stewart and copyright2016. Section1.4, printed pp.17–19: equation(1.62), differential of a time-dependent holonomic constraint; Figure1.10 and its moving-wire discussion distinguish actual displacement from virtual displacement at fixed time. Equations(1.64)–(1.66) give virtual work and generalized forces.