PeterH:
retrolefty:
Two ping pong balls will drop at the same speed regardless of weight difference so their air resistance/drag AND speed will be the same.That's simply not true.
The nett downward acceleration is weight minus drag divided by mass. If drag is negligibly small (relative to weight) then it can be ignored and then numerator and denominator are proportional to mass so the acceleration is independent of mass. This is the classic 'falling cannon ball' experiment.
Which is what the OP is wishing to demonstrate with his 40ft dropped ping pong ball experiment and that is the context for my comments to the OP.
Change the circumstances so that drag becomes significant (relative to weight) and the numerator is no longer proportional to mass and acceleration is no longer independent of mass. The change could be either making the speeds higher (drop the objects from a greater height) or make the mass smaller (so that the drag becomes more significant at the speeds encountered in the experiment) or change the medium so that the drag is higher (for a given shape/speed).
Are you familiar with the concept of terminal velocity? An empty ping pong and one the same size filled with water have different terminal velocities, because of the effects of drag.
And ping pong balls falling from 40 feet will reach terminal velocity? Again my point is to link Sir Isaac Newton's claim to the experiment that the OP is wishing to reconstruct. Why must you change the context to try and show different results for a different experiment?