Ein = P t
Eout = 0.5 m v^2
= 0.5 m a^2 t^2
= 0.5 m (F(P)^2 / m^2) t^2
= 0.5 (F(P)^2 / m) t^2
Eout / Ein = ( 0.5 F(P)^2 / ( m P) ) t
= k t
OU occurs for all t > 1/k
Therefore all propellantless propulsion schemes, whereby the motive force is a function of the on-board power, are inherently OU after some characteristic time T
