Let's say you have a body in motion, a car, an airplane or hovercraft - does not matter, looking for basic laws of physics here. 1. You know the weight. 2. You know the center of gravity at rest. 3. You know the center of lift (if applicable). Let's say our object weighs in at 600 lbs. Lets say our object is going 30 mph. Q1: How much does the center of gravity or weight shift back? Q2: Lets say I need to start or stop very quickly, how do I calculate the location shift of CG backwards and forwards? I think the key is taking the the actual weight and turning it into mass, then take into account speed the horizontal force, which in turn may reduce the gravity force or weight over a given time peroid. An actual example would help, then I can apply it to my situation.