Toni Foster's reported motions on frames surrounding Z-313 are physical
evidence of alteration. The film shows she was moving at a fast pace, stopped
for one frame then continued her gait. These changes in speed occurred in
around one frame period. They represent an acceleration of sizable magnitude,
namely eighteen times her change in speed.
Newton's law of motion relates force, F, to mass, m, times acceleration, a. By using the concept of weight, W, we can replace the mass by weight divided by the acceleration of gravity, g.
F = (m)(a) = (W/g)(a)
The acceleration of Toni Foster was eighteen times her change in speed, dV. Expressing dV in ft/sec, a = 18 dV ft/sec2 and using g = 32 ft/sec2 gives
F = 9/16 W (dV).
For a moderate pace of 4 ft/sec, the Zapruder film reports Toni Foster exerted a force of 2.25 times her body weight. Further complications arise when we consider the Zapruder film shows Toni Foster's feet nearly directly below her torso. This position frustrated use of her powerful leg muscles.
