The applet below shows a few constraints that arise when designing a car profile. For example, to design a curve that is the profile of a car hood, space must be left for the engine, and visibility for the driver must be maintained. In this applet, we try to see what happens when one attempts to use parabolas in various orientations for this task. Of course, in practice there would be many other constraints as well. However, this simple example is enough to learn about curvature.
insert Java applet here
Go back to the concept page to read more about the difficulty with parabolas.