第一定律I. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.第二定律II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector.第三定律III. For every action there is an equal and opposite reaction.参考资料：http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html本回答被提问者采纳
