1) Every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as its compelled to change its state by force impressed.
2) The change of momentum of a body is proportional to the impulse impressed on the body, and happens along the straight line on which that impulse is impress.
3) For a force there is always an equal and opposite reaction; or the forces of two bodies on each other are always equal and are directed in opposite directions.
