Talk:Theory

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Revision as of 11:25, 29 May 2015 by Saucyjack (talk | contribs) (Added note about moving K.E. discussion to http://emdrive.echothis.com/Generic_EM_Drive_Information)
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Somebody wrote:

_________________

Back-of-the-envelope "Kinetic Energy Debunk"

Given:

[math]f=ma[/math]

and

[math] e=\cfrac{1}{2}mv^2 [/math]

then

[math]a=\cfrac{f}{m}[/math]

So if this device can produce a constant force then it will produce a constant acceleration.

BUT!... because Kinetic Energy is proportional to the SQUARE of velocity, and the energy being put in is constant, then at some time the attained velocity will mean there is more kinetic energy in the device than has been put in to the device. Yay, free energy! _____________________

That's not a debunking theory, it is an energy and acceleration consideration. It fails to take into consideration the 2nd law of thermodynamics, it makes an unwarranted assumption that the acceleration of the device (and hence the force F= m *a) should be constant under constant power (the power required for constant acceleration is not explicitly discussed), and it fails to consider that in many processes like for example a collision against a wall momentum is conserved but kinetic energy is not.

This same "debunking theory" could be applied to any flying vehicle: rockets are not possible because, to start from an initial condition at rest, it means that they must accelerate, but constant acceleration means an energy puzzle, therefore there cannot be any rocket. (It fails on the same philosophical grounds as Zeno's paradox https://en.wikipedia.org/wiki/Zeno%27s_paradoxes#Paradoxes_of_motion that motion is not possible. This time by making the unwarranted assumption that the EM Drive will have constant acceleration at constant power.)

The issue of energy conservation has its own section in this wiki, and it has been better addressed by @frobnicat.

Perhaps the writer was unaware of the section titled "http://emdrive.echothis.com/Generic_EM_Drive_Information", and that section should be better titled "Energy Conservation"

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I'm not sure who wrote it as they were anonymous, all I did was format it. I agree it would be better suited to http://emdrive.echothis.com/Generic_EM_Drive_Information, along with your rebuttal.