|MadSci Network: Engineering|
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.
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