Naturally, the energy of the resting ellipsoid, may not contain the velocity .
Thus, since is invariable, is variable:
or by series expansion
The energy increase caused by motion, is thus in first approximation
thus the inertial mass .
By that, the mass defined by inertia would only be constant at small velocities, and would increase with increasing velocity. Since inertia as well as gravitation emerging from the body, is proportional to the number of quanta composing the body, it follows, that the mass defined by inertia must be proportional to the one specified by gravitation. If a body with mass , is attracted by a body of mass up to a distance of , then the electromagnetic energy store of gravitation is diminished by the amount , where denotes the gravitational constant.
This energy is transformed into kinetic energy to produce the velocity . Thus we have
Instead of it, we can write