d'Alembert's principle
noun
d'A·lem·bert's principle
¦daləm¦be(ə)rz-
: a principle in mechanics: the reaction due to the inertia of an accelerated body (as a baseball) is equal and opposite to the force causing the acceleration (as the blow of a bat upon the baseball) and results in a condition of kinetic equilibrium compare law of motion sense 3
Word History
Etymology
after Jean LeRond d'Alembert †1783 French mathematician, its formulator