Voice of Principle comments on my dialogue with olblucat

...I have observed objects falling from heights and their destruction.
Practical experience says the destruction is greater as the starting point of the fall begins. The force of impact is much greater also.

You mean the destruction of falling objects is greater the higher the object falls from? I agree. Were did you find me stating the contrary? I have not denied that there is some sort of proportion between the physical work done in lifting an object, the kinetic energy (momentum) of it falling and the impact (new physical work) done when it smashes. I have stated a problem: between the lifting and the falling there is no entity internal to the object or otherwise per se actual that preserves this proportion.

====<1> Hans: Your error in understanding the nature of potential energy is due to the fact that you are looking only at the object. Potential energy involves an object + the gravitational field in which it finds itself. The distance of the object from the field's center of gravity + the distance over which the object will free fall determines the magnitude of the potential energy. <1>====

To VoP: NB will fall. Not something that is actually but something that will potentially. Which is basically what I am saying.
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That means: potential energy is not a positive real entity, the conservation of energy is rather a theoretic conservation of figures on a paper than a conservation of any positive entity.

====<1> If that were the case, then perpetual motion machines would be possible and the world's energy problem would have been long since solved. <1>====

To VoP: how does that follow?
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That means: physical energy cannot be the ultimate ground of existence, as it has been usually presented to the general public since it was discovered by Hiroshima that physical matter certainly wasn't.

====<1> An unfounded conclusion. <1>====

To VoP: the conservation of matter as ground of existence and energy as ground of movement independently of each other seems to have been disproven by Hiroshima bomb.


HGL

The reasons for an object losing it's energy in linear or angular momentum.

Again, as with the first part, I have observed many times this application in real time.

The above two have direct bearing on two of my own interests. Ballistics, both rockets and cannon shell, and aerodynamics as applied to both flying modelplanes and ground vehicles.

Now, I am confused as to what you believe controls all the various physical actions observed and studied and the results obtained.

If my interpretation of your beliefs are correct, then I can throw 100 years of testing and designing of airfoils out the window, as well as years of windtunnel testing.

This hasn't considered the same effects as applied to water craft such as the America Cup ship and sail designs.

You speak of theory, while I have to apply it.

Please, Oblucat. Would you do less interpretation of what I mean and what that would mean to ballistics and more of answering the points raised? Or was that the answer to my point: what proof is there that only air friction is responsible for any loss of momentum?

====<1> The proofs are many. Changing the shape of the arrow, particularly the arrow head, can improve or degrade flight distance in a mathemtically predictable fashion based on an analysis of aerodynamic factors. The same analysis can be applied to any object traveling through the atmosphere (using an appropriate data base describing the physical characteristics of the object).

Orbiting spacecraft outside the atmosphere experience virtually no frictional effects due to collisions with air molecules (the noteworthy exception being the solar wind), and therefore remain in orbit for centuries, millenia, or millions of years (duration depending on the mass of the craft and the nature of the chance atoms and molecules it encounters, space not being a perfect vacuum).

Perhaps the best example of air resistance was the recent tragedy involving the space shuttle Columbia. As the vehicle broke up and lost aerodynamic integrity, frictional forces created by its interaction with the upper atmosphere consumed so much energy that the pieces of the vehicle ended their flight hundreds of miles short of their destination, Cape Canaveral. <1>====

To VoP: you reason mostly as if rebutting the position that air friction were not a cause for loss of momentum. That is not my position. As for satellites outside atmosphere, the artificial ones have only been up a few decades, and the millennia of the others is begging the question: how do you, not explain, but prove that lack of air fricion and momentum preserved by such lack are the causes of that movement?

Hans Georg Lundahl