1. The problem statement, all variables and given/known data I'm trying to compare the velocities at 5 meters of three projectiles subject to air resistance: the first with an initial velocity of 121.632 m/s, the second with an initial velocity of 136.8m/s, and the third at 182.442 m/s. All three projectiles have a mass of 2.0x10^-4 kg (m), a cross sectional area of 2.81x10^-5 m^2 (A), and drag coefficient of .47 (Cd). Density of air is assumed to be 1.204 kg/m^3. 2. Relevant equations The equation I have been primarily been using is the drag equation Fa = 0.5Dv^2CdA My initial plan was to use F = ma and Vf^2 = Vi^2 + 2a[itex]\Delta[/itex]x. However, I realized after doing these calculations that Fa changes with respect to velocity. 3. The attempt at a solution This is my attempt to the solution of finding the velocity after 5 meters for 121.632 m/s. Fa = -(0.5)(1.204)(121.632 m/s)^2(.47)(2.81E-5) = -1.2E-1 Which I then realized that only applied initially at launch. So I tried taking the derivative with respect to time. dFa = (.47)(2.81E-5)(dv/dt) I am fairly stuck at the moment. Where do I go from now? If there is not enough information, what information do I need and what hints would you give to experimentally gain this information?