An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Any equation that describes the motion of objects, i.e., variation of velocity, distance covered, acceleration, etc., as a function of time; e.g., V = V₀ + at, S = Vt + (1/2)at².
2) For a fluid, a relation, in its most fundamental form, equating the rate of change of momentum of a selected portion of fluid and the sum of all forces acting on that portion of fluid.
3) In quantum mechanics, an equation that governs the time variation of the → state of the system. → Schrodinger equation. However, in the Heisenberg formulation of quantum mechanics the equation of motion does not involve the states, which in this case is time independent, but rather the → observables of the system.

→ equation; → motion.