Any math any time anywhere. The problem is no math has been cited to support FE. I can't point to a flaw in your physics if you don't show me where any physics is used.
Some simple ones:
a=2d/t^2
where d is distance, t is time and a is acceleration. Very useful when you want to find out the rate of acceleration of the FE.
x = V*cos(theta)*t
y = V*sin(theta)*t -.5at^2
where V is velocity, theta is the inclination angle, a is the same as before and t is time. Neglecting air resistance, this nicely provides the trajectory of an object.
Oh, and let's not forget my personal favorite:
w = (u+v)/(1+u*v/c^2)
where u is the current velocity of the FE, v is 9.8m/s, c is the speed of light and w is the resulting velocity from the addition, to be used as u in the successive iterations.