Hello all. I'm investigating a little bit about stokes law in order to understand the settling velocity of falling particles and on the net i encountered with 2 different formulas and i simply can't find the reason why they are different. every formula gives me a different answer. The 2 formulas are : 1. Vt=gd^2(Pp-Pm)/18u - 2. V=2/9*d^2*g*(Pp-Pm)/u - Any idea why they are different ? Thanks.