Motion

First: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Second: 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.

Third: For every action there is an equal and opposite reaction.