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Ki is rattling a bag of chicken bones in the eyes of some. I have a view of Ki, as a physical cyclic phenomenon that has a demonstrable physical basis -- and it really does rattle a bag of bones, but no chicken is involved -- unless you're just into that kind of thing -- not that there's anything wrong with that.
In response to a question about impulse of a strike it struck me (pun intended) that it is a matter not just of length of time, but of timing (in the sense of rhythm) in the frequency of the strike at impact. It matters -- not merely speed, but the actual frequency of the impact/react timing.
It requires some teensy background on force, momentum and Newton's Third Law (action= reaction).
The commonly understood linear equation F = ma can be rewritten as Σ F= dp/dt where the sum of forces is the change of momentum (p) with respect to time (t). Impulse, J = F * dt = dt* F = dt*dp/dt = dp, which is simply the change in momentum.
Very, very rarely can real world forces be treated as purely linear. Most forces are usually:
1) not isolated (there are other forces in play, with different 3D vectors),
2) dynamic, and the amount of force is changing rapidly with respect to time, and
3) eccentric (off center) as to both or all objects involved, thus involving moments (potential rotations) or actual rotations (angular momentum).
When an object is struck what strikes back (3rd law) is its moment of inertia -- its inherent reaction to havi