coordinate systems
scenario
Consider a flat disc floating in free space so that there are no gravitational or friction factors. We shall use a relative coordinate system centered at the center of the disk, and moving in concert with the disk in both translation and rotation.
The disk is indicated here in the horizontal Z plane. Since we have established the coordinate system to be relative to the disk in both translation and rotation, it makes no difference if the disk is considered to be rotating (spinning around the XY) or stationary. That is, the concept of both linear and rotary momentum of the disk is simply meaningless
Also in this relative coordinate system, a force of any form which might be considered to be applied to the disk cannot possibly be reflected in the form of acceleration of the disk within this reference frame.
And if there is no acceleration possible then the concept of inertial resistance becomes meaningless. In essence the concept of F=MA simply has no application where the coordinate system is chosen relative to the object of interest. There is one other very interesting point. If inertial resistance does not exist to provide a resistive counter-force, then the imagined force being applied can not possibly have any value other than zero. No possible magnitude, and the direction is immaterial -or meaningless.
significance
We have just proven that the concepts of motion, force, inertial resistance, and momentum are all meaningless unless some frame of reference which is separate and independent of an object of interest is first imagined into existence. Furthermore, it is evident that all such factors are totally dependent on the choice (location and motion) of that imaginary external, independent reference coordinate system. The associated values can be as unbounded in number as man�s imagination for creation of coordinate systems - and of the arbitrary irrelevant values which he selects as the units of measure which should be used within the imagined coordinate system.
The current scientific wisdom that every physical body inherently possesses all of these properties may be an accepted dogmatism, but that is only because man has been educated to believe in the reality of imaginary coordinate systems which exist independently of the objects which we perceive to exist. Usually we select either our own personal �consciousness� or the Earth on which we live as the center of a fixed coordinate system, and then treat every other object in the universe as if it can be observed and measured in terms of our own imaginary coordinate system.
This practice may be as unrealistic as the practice of imagining that every other person in our universe must perceive any specifically selected person exactly as we ourselves perceive that selected person. The reality is that there are as many different views of the selected person as there are different persons making the observation. Every observation is different, and relative only between the object of interest and the specific observer of that object.
conclusions
In the case of the disk above, the imagined factors of inertia and the response to applied forces is totally dependent on the observer�s imagined factor of rotational rate of the disk. We may imagine it to act in accordance with the rules we have established for a non-rotating disk - or we may imagine it to act in accordance with the rules we have established for a gyroscope. And we may then derive very different conclusions about the result of an imagined application of force - which can not even exist in the relative coordinate system.
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