Me? I'd make it a whole lot simpler. I'd leave the system definition as the simply the machine and call it an open system. The boundary of the
system would be the crank, and external input is a force applied to the crank. This accounts for the mechanical work done on the system by the
environment. Simple. OPEN!!!!!!!!!!!!!!!
Of course, how would we know the magnitude of force (or torque) actually applied to the crank as a function of time? That problem exists whether the
problem is handled your way or mine. The answer is, you can't, not with the information available. It's arbitrary. If a guy is turning the crank,
the amount of force applied is subject to his volition and whim. Without knowing the force function, nothing more can be said about the system's
However, we CAN specify the action of the system under the influence of an EXTERNALLY imposed force F(t), if the properties of the SYSTEM are well
understood. We can set up and solve the equations of motions for the OPEN SYSTEM subject to external arbitrary force such that, if a force function
is given, the action of the system is known (predictable).
In fact, since the system of interest is the alleged perpetual motion machine, that's the only solution we're after. We don't care if it's a person
or a motor turning the crank; both are capable of supplying an ARBITRARY force over time. Well, hell, if we solve the equation of motion for the
machine given arbitrary force, we don't need to know or care what's turning the crank.
And that's how physics is done. Open system, closed logical model.
Something you intuitively know, but have no idea how to express in the language of science. So, not having actually solved a problem like this, let
alone hundreds, you ascribe meaning to terms according to your own understanding, which is wrong.
Your way: expand the system spatially all the way out to the sun, and conceptually through all the processes from nuclear fusion to the photoelectric
effect, and everything in between, so that it can be a "closed" system. This is what you say is necessary to account for the dynamics of an
infinitesimally insignicant machine located somewhere in a sun-earth system. When all we're interested in is the little machine...
I laugh in your general direction.
It's also the foundation of your error in your critique of Bazant. You fail to account for the fact that the system under study, a tower, is an open
system with the boundary condition of coupling to ground. You forgot about ground, but Bazant didn't. The only error is yours, and it's colossal.
An error no freshman physics student would make.
I always understood what you meant with your imprecise concepts and terminology, and was initially going to agree. What you probably meant was that
all matter and energy crossing the boundaries of the system must be properly accounted for. That's what I said in correcting you, referring to
external input. But I realized that what you wrote did not match your intent, and what you wrote was wrong. So I told you so. Once told, you still
I'm not going to agree with you when you're wrong, just to get an apology I'm owed and deserved many times over, going a long ways back. From someone
who deserves not one iota of further consideration.
Prediction: as you read this line, you are guilty of not reading all the words preceding it. This is one of the reasons you still have no
understanding of physics. For all our interaction, you could've absorbed enough to get through the first two years of an undergrad degree, by
edit on 5-2-2012 by IrishWristwatch because: (no reason given)