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Compound Machine

Introduction and examples of a machine that consists of more than one simple machine.

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Too Good to Be True

Too Good to Be True

Credit: Charles Redheffer
Source: http://commons.wikimedia.org/wiki/File:Redheffer_machine.JPG
License: CC BY-NC 3.0

The contraption in this sketch is a compound machine that caused quite a stir in the early 1800s. Its creator, named Charles Redheffer, said it was a perpetual motion machine. This is a machine that can keep running without any input of energy.

The Back Story

  • Can you imagine the benefits of a perpetual motion machine? Using it would require no energy, and its motion could be used to run other machines.
  • In fact, when Redheffer exhibited his machine, for which he charged admission, he demonstrated how it could turn a gear that would run another device.
  • Inventors had been trying to create perpetual motion machines for centuries without success.
  • Was it really possible that Redheffer had achieved this amazing feat? Watch this re-enactment of the story of Charles Redheffer and his perpetual motion machine to see for yourself: https://www.youtube.com/watch?v=RjU39AWM8qM

What Do You Think?

Use the links below to learn more about Redheffer and perpetual motion machines. Also read about the Sokal affair. Then answer the following questions.

  1. Is it possible to create a perpetual motion machine? Why or why not?
  2. How did Redheffer’s machine really work? Why do you think Redheffer created and exhibited his machine?
  3. If Redheffer had been a serious scientist, how would his “invention” be considered in light of scientific ethics?
  4. Recently, a scientist named Alan Sokal did something that other scientists found questionable. What did Sokal do, and why did he do it?
  5. Do you think that Sokal’s behavior violated scientific ethics? Why or why not?

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Image Attributions

  1. [1]^ Credit: Charles Redheffer; Source: http://commons.wikimedia.org/wiki/File:Redheffer_machine.JPG; License: CC BY-NC 3.0

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