In this work is discussed the question concerning the origin and development of the principle of virtual work as a fundamental principle in the study of the analytical mechanics, and particularly of the static equilibrium of an initially motionless system. The seminal contributions of Stevin, Galileo, d'Alembert and Lagrange are emphasized. Furthermore, the concept of holonomic constraints and virtual displacements are presented. Some examples of how to apply the D'Alembert's principle expressed under the D' Alembert-Lagrange equation are introduced, in order to show how this fundamental principle of static and dynamics can be successfully employed.
virtual work; virtual displacement; constraint; D'Alembert's principle
