DYNAMICS

the science which deals with the motion and equilibrium of material bodies. It is subdivided into kinetics and statics, dealing respectively with the motion and equilibrium of material systems. Newton’s laws of motion supply the foundation of the subject. These laws demand the recognition of ma and force. The preliminary subject of kinematics deals with the motions of points, lines, and surfcces without reference to ma or force. Starting from the fundamental laws, it should be po ible to find a solution for every problem which can be stated in dynamical terms. Certain derived principles are useful in solving certain types of problems (e.g.) D’Alembert’s, by means of which every kinetic problem can be expre ed as a statical problem; also the conservation of momentum and of movement of momentum, as well as the principles of energy. The principle of the conservation of energy has brought about the dynamical treatment of subjects formerly excluded, such as heat in thermodynamics, electricity and magnetism in electro-dynamics; also hydrodynamics and aerodynamics, dealing with liquids and gases respectively