Re: how does a ferris wheel work?

Terms like wedge or inclined plane, lever, screw, wheel and axle, pulley
and such are often used to make a list of so called “simple” machines which
in combination can make more complex mechanisms.  We use these terms not so
much to classify all the different devices around us as we do to understand
what they are made of and how they work.  The fancy term is deconstruction.
 We deconstruct a device by looking at it as being made up of interacting
simpler machines.  Each of these simplest machines has its own way of
reacting to force applied to it.  Knitting together the equations that
describe these reactions for each interacting machine is a first step
toward working out the behavior of the whole thing.  Even though it looks
like nothing more than a large wheel  a Ferris wheel is actually a fairly
complex device.  Because it is such a combination of simple machines you
really can’t classify it as just one of them. Whether it is the original
Ferris wheel (see http://www.acweekly.com/view.php?id=3695 for a nice brief
history of the wheel and its maker) or something as modern as the London
Eye the ride is composed of many simple machines.  It may be driven by 
hydraulic motors, pulleys, or chains and gears like a cog toothed rail way.
 Something like the last method may be what your teacher had in mind when
saying it was both, after all most gears look like wheels with teeth.