I understand the derivation of the equation Force=power/velocity, but I'm not sure I quite understand the physical interpretation of this. If you had a constant force acting on a particle in a vacuum, then it would gain velocity and as it did so the power would have to go down for the force to be constant. Since the only transfer of energy is into kinetic energy as the particle is in a vacuum. If the power goes down this means the rate at which it gains kinetic energy decreases. This means its acceleration decreases but that doesn't make sense to me, why given a constant force is acceleration not constant. If you combine it with F=ma this implies that the mass of the particle has to increase for this to be the case. Am I intepreting all this correctly?