Yes, and this is why KE = 1/2 MV^2 - ie., why the acceleration unit cost escalates; a given force has to be applied over an ever-greater distance as velocity (time rate of change of position) increases. Alternatively, we could hold displacement constant and progressively raise the force magnitude.
Yet Craig still seems to have a point - without some kind of corporeal reaction mass, what is an EM drive's velocity actually relative to? What's its reference frame, if not the thing it's pushing against? To illustrate the conundrum, suppose i have an EM drive aboard a train, and you the observer are standing on the platform as the train passes through the station: I fire the engine, and it accelerates by 1 meter / sec. Suppose the engine weighs 10 kg. From my perspective, its KE has increased by 5 Joules - ie. it's perrformed 5 J of mechanical work, regardless of how much more energy may have been wasted to heat. But if the train was already travelling at 10 m/s, and the drive accelerated in the same direction, then from your stationary perspective the drive has accelerated up from 10 to 11 m/s - and for a 10 kg mass that's a workload of 105 J - bringing its KE up from 500 J to 605 J. So, has the drive burned 5 J or 105 J? If i cheated - the drive doesn't really work, and i just gave it a surreptitious shove - this same paradox is resolved by a corresponding deceleration of the train - ie. if i accelerate a small mass against the inertia of a larger mass, the latter is decelerated and net momentum is conserved. Except here, the drive ISN'T pushing against the train. Yet it still benefits from its ambient velocity. Net momentum is NOT conserved, and neither is energy. And so the question arises, how does the EM drive "know" what its reference frame is? Shawyer claims (or seems to imply) that the unit cost of acceleration increases as we would normally expect (distance over which a given force is applied keeps rising) - but how does it measure "distance"? Relative to what, exactly? Without physical reaction mass, such a system has its own unique reference frame - from within which, energy may be conserved, but which from without, cannot be. I mean this not as a crtitique against the plausibility of such systems, and share the prevailing cautious optimism. But if they do work, then we also have an energy anomaly. In the many years i've been researching classical symmetry breaks, one thing has become clear - the only way to explain away a real symmetry break is to invoke another somewhere else up or downstream (it's a standard recourse for pseudoskeptics). As much as i'd welcome free energy, momentum and FTL travel, and despite Shawyer's assurances everything's classically consistent, these enigmatic implications remain.. for me, at least. On Mon, Mar 14, 2016 at 4:17 AM, <mix...@bigpond.com> wrote: > In reply to Craig Haynie's message of Sun, 13 Mar 2016 21:08:43 -0400: > Hi, > [snip] > > Note the use of the word "acceleration". > > Acceleration produces a force. Force times distance = energy. > > >This doesn't make any sense: > > > >"For a given acceleration period, the higher the mean velocity, the > >longer the distance travelled, hence the higher the energy lost by the > >engine." > > > >Since we're not talking about relativistic speeds, then the idea that a > >device will consume more energy, over a given period of time, simply > >because it's moving, would violate Einstein's Special Relativity which > >says there's no preferred frame of reference. The moving object cannot > >be said to be moving at all. > > > >Craig > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/project.html > >
