The following video(s) are a walk through of a situation involving an object falling through air. It is similar to how I solved #4 in the Free Response. There are some small differences in the math, either way is suitable. Pay close attention to setting up and solving the differential equation for v(t), which begins at approximately the 5:10 mark of Part 1 and continues in Part 2. (Note: His first V-t graph will differ than the one in our solution because we are graphing from the point a parachute has opened, aka terminal velocity begins! Near the end he does do a graph like the one we were asked in #4.)