Center of Mass Shifts: Demonstrating Motion Without Forces

Motion emerges from center of mass (COM) shifts when energy overlaps (From Energy to Motion, DOI 10.5281/zenodo.23441924). Between a surface and the air, those overlaps are catches, and countless catches at every patch add up to be read on a scale. A disc on a balance beam makes the shift visible. Spinning the disc passes air over both faces alike, while a blower aimed edgewise passes faster air over the top face only. Three results follow. • The blower moves every disc up: by from 0.32 to 0.73 g with the disc stopped, and by 0.60 to 0.95 g with it spinning. The blower's share roughly doubles with the spin: the jet keeps bringing fresh air to the spinning top face, while the sheltered underside spins through air it carries round with it. • The surface sets the response, in its size and in its shape with speed. ASA reads 38 to 44% above PLA. In speed sweeps, ASA rises and then eases, polyaspartic keeps rising at the top speed, and a water repellent levels off. The surface builds the first layers of air, those build the outer layers, and the layers are part of the shape the air passes. • The faces add: a disc with ASA on top and polyaspartic underneath eases at the top speed by about the amount the polyaspartic underside predicts, within the precision of the measurements. A companion paper on lift (forthcoming) reads the same catches on a wing to produce a fundamental lift formula.