We conducted an experiment to test if proper orbital angular acceleration of two rotating bodies within a three-body system due to proper linear acceleration of the system would cause the center of mass momentum of the system to increase as predicted by Euler’s first law? The result would be significant because the increase in momentum would be due to the reaction of spacetime itself on a body that is forced off its natural geodesic path due to proper linear acceleration and not due to physical, external contact forces. Thirty test trials were conducted where two spheres were constrained to travel around quarter-circle tracks. This caused centrifugal reactive forces on the inner walls of the curves, forcing the system to linearly accelerate. This proper acceleration induced an increase in the orbital angular speed of the spheres by spacetime itself due to the non-geodesic motion of the spheres. After 30 test trials the 1 mean value of known external friction impulses acting on the three-body system accounted for only ~ 8.2 per cent (standard deviation .037 and standard error .0068) of the increase in the final momentum of the system, leaving a ~ 91.8 per cent discrepancy. This result highly suggested that spacetime itself contributed ~ 91.8 per cent of the total external impulse on the system.