Mathematica 10.3.1, windows 7, 64 bit:
vel = Quantity[3000, "Feet"/"Seconds"];
grav = Quantity[1,"StandardAccelerationOfGravity"];
Plot[vel*t + 1/2 (-grav) t^2, {t, Quantity[0, "Seconds"],
Quantity[3, "Seconds"]}, PlotTheme -> "Web", FrameLabel -> Automatic, Filling -> Bottom]
