Newton's laws of motion are three physical laws which provide relationships between the forces acting on a body and the motion of the body, first compiled by Sir Isaac Newton. Newton's laws were first published together in his work Philosophiae Naturalis Principia Mathematica (1687). The laws form the basis for classical mechanics. Newton used them to explain many results concerning the motion of physical objects. In the third volume of the text, he showed that the laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion. Briefly stated, the three laws are: An object in motion will remain in motion unless acted upon by a net force. Force equals mass multiplied by acceleration. To every action there is an equal and opposite reaction. (wikipedia)
