What can you conclude about the behavior of each kind of car by looking at its
gain curve? Are any frequencies especially good or bad? Do any of the
suspensions seem particularly exotic? Think about what the graphs tell you
before you look at our commentary.

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Notice that the ``boat'' bounces wildly at low frequencies, with the gain
peaking at around 4.3 at a frequency of two Hz. This means that if you
drive over a series of three-inch bumps at a rate of two/second, the car will
bounce up and down by over twelve inches. You could easily lose control of
such a car if you hit the wrong kind of bumpy pavement. Fortunately, this
behavior disappears at higher frequencies.

The ``truck,'' with its stiff suspension, has a gain of close to one for all
frequencies. This means that the truck will bounce up and down by about the
same height as the bumps, regardless of how fast you're driving. Of course,
this is about the same behavior that a piece of lumber or a brick would have if
it were sliding down the road!

The ``sedan'' has quite an interesting curve. The gain steadily goes to zero
at seven Hz, and then goes back up again to a small non-zero value. There's a
reason for this. The human body is particularly uncomfortable when it is
vibrated seven times per second. This designers of the ``sedan'' have
evidently taken than into consideration.