There's something important we've forgotten, which will help solve several conondrums.
The force of an Allomantic Push/Pull is proportionate to the mass of the metal being affected.
We have seen a hundred times throughout the books that the bigger a piece of metal, the better an anchor it is and the more force an Allomancer can exert on it. In view of this point, I venture to propound the following equation.
Fallomancy = k*mobject*Rb*[mpure]/d
Fallomancy is the force exerted on the allomancer and the metal. It is positive for Pushes, negative for pulls. Units are Newtons for this example.
k is the allomantic constant, which represents the allomancer's strength in the given metal. It is positive for steel, negative for iron. Units are Newton-meter-seconds/kg2.
mobject is the mass of the metal being pushed on, in kg.
Rb is the burn rate in kg per second.
[mpure] is the purity of the metal, represented as a percentage of ideal purity. No units.
d is the distance in meters.
After this, the ordinary F=ma equation applies.