Kinetic Force
The kinetic force Kab exerted on a particle A of mass ma by another particle B of mass
mb , caused by the interaction between particle A and particle B, is given by:
Kab =

ma mb
(˚aa − a˚ b )
mcm

where mcm is the mass of the center of mass of the universe, a˚ a and a˚ b are the accelerations
˚
of particles A and B relative to the universal reference frame S.
From the above equation it follows that the net kinetic force Ka acting on a particle A of
mass ma , is given by:
Ka = ma a˚ a
˚
where a˚ a is the acceleration of particle A relative to the universal reference frame S.
From page [1], we have:
ma a˚ a − Fa = 0
That is:
Ka − Fa = 0
Therefore, the total force (Ka − Fa ) acting on a particle A is always in equilibrium.

Bibliography
A. Einstein, Relativity: The Special and General Theory.
E. Mach, The Science of Mechanics.
R. Resnick and D. Halliday, Physics.
J. Kane and M. Sternheim, Physics.
H. Goldstein, Classical Mechanics.
L. Landau and E. Lifshitz, Mechanics.

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