Is the energy gained by a particle moving at a high velocity a product of acceleration or can it arise in an object moving at constant velocity? I mean....OK, thought experiment. I haved a 100 GeV spherical mass moving through space relative to the earth at 10 m/s. I now accelerate that mass to a velocity, v', relative to the earth whereby now the traveling mass has an energy of 200 GeV. I now stop accelerating the mass. I'm assuming now that the mass will continue on indefinitely traveling at v' with an energy of 200 GeV relative to the Earth. Is that correct? I guess the larger question I'm asking is, is it only the acceleration of the mass that imparts energy to that object? Such that the actually velocity per se has nothing to do whatsoever with imparting energy to an object? In other words, accleration gives energy/mass to an object and deceleration removes energy/mass? While the actual velocity per se of the object has nothing to do with it?