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D'Alembert's principle





The observation that Newton's third law of motion (that to every action there is an equal and opposite reaction) applies not only to systems in static equilibrium but also to those in which at least one component is free to move. Thus when a force F is applied to an unconstrained body of mass m endowing it with acceleration a, there is an equal and opposite inertial reaction -ma.


Related category

   • CLASSICAL MECHANICS