Redefining Gravity and Newtonian Natural Motion

Traditional Newtonian mechanics treats gravity as one of the forces contributing to the acceleration of a body in motion. Newtonian natural motion is defined relative to an abstract inertial space where gravity is non-existent and free body velocity motion remains constant unless modified by applied force. With this interpretation, gravitational force is an embedded characteristic whose effect on body acceleration is not measurable by accelerometers, the traditional instruments used in inertial navigation systems to measure acceleration relative to inertial space. This paper introduces a revised interpretation in which gravity is an integral part of natural motion, and natural motion can only be modified by applied non-gravitational forces. With this new interpretation, gravitational force is non-existent, all forces impacting natural motion are measurable by accelerometers, and gravity can only be determined relative to its value at another location. Equations of motion are presented for the new interpretation and used to describe classical known situations: forces experienced on the surface of the earth, "zerogravity" in free-fall and earth orbit, creating "zero-gravity" in an aircraft, the general relativity principle of equivalence between inertial and gravitational mass, linear and rotational dynamics of mass groups, and a measurable definition of inertial coordinates including its use as an inertial angular reference.