Dynamics Isaac Newton (1642-1727) published Principia Mathematica in 1687. In this work, he proposed three " laws"of motion Law 1: An object subject to no external forces is at rest or moves with a constant velocity if viewed from an inertial reference frame Law 2: For any object, FNET =2 F=ma Law 3: Forces occur in pairs: FAB =-FBA (For every action there is an equal and opposite reaction Physics 121: Lecture 7, Pg 10Physics 121: Lecture 7, Pg 10 Dynamics Isaac Newton (1642 - 1727) published Principia Mathematica in 1687. In this work, he proposed three “laws” of motion: Law 1: An object subject to no external forces is at rest or moves with a constant velocity if viewed from an inertial reference frame. Law 2: For any object, FNET =  F = ma Law 3: Forces occur in pairs: FA ,B = - FB ,A (For every action there is an equal and opposite reaction.)