One fo the interesting things that come from our analysis of the drag force is the concept of a terminal velocity. Basically if we apply a force of fixed magnitude to a solid in a fluid the solid will accelerate because there is initially no drag force to counter-act the applied force. As the velocity increases, however, the drag force increases dramatically until eventually it is equal in magnitude but acts in the opposite direction to the drivin force. At this point the velocity has reached what we call the terminal velocity which.
Cases to consider could be the max speed of a car with a motor capable of yielding a certain forward force. The example we shall consider is the free fall through a fluid. Now there we have a well defined driving force with which to compare the drag force.
At the terminal velocity of a free falling object we have
Now we regain our everyday experience with falling objects. Large area and small mass fall much slower than small area large mass objects.