Magnetmotor
Perpetuum Mobile of Villard de Honnecourt (about 1230)

Perpetual motion – “motion that continues indefinitely without any external source of energy; impossible in practice because of friction.”

It can also be described as “the motion of a hypothetical machine which, once activated, would run forever unless subject to an external force or to wear”.

Throughout history, people have worked to make such a device. Leonardo da Vinci and thousands of other inventors have tried. Although there are many designs for perpetual motion machines, there is no such thing. Using basic physics, math and related subjects, there are several explanations for why there can not be a perpetual motion machine. There is a scientific consensus that perpetual motion in an isolated system would violate the first and/or second law of thermodynamics.

Perpetual motion machine inventors often misapply elementary physics. For that reason it emphasizes those mechanics principles applicable to machines. However, these are basic to all of physics, and if not properly understood, can adversely affect understanding of everything else in physics.

If you don’t understand the explanation, you see why engineers spend so much time learning about what is possible in the real world.

Machines and Perpetual Motion

What do you think? Is perpetual motion possible? If not, why not? Consider all the components of machines and motion. Some design challenges just can’t be solved. That is another important part of working on an engineering problem – there may not be a solution. Whether there is a solution or not, follow the Engineering Design Process to guide your investigation.

  • Ask – What sort of machine could possibly be a perpetual motion machine? Are there applications where perpetual motion would be useful?
  • Imagine – For there to be perpetual motion, what might work? What materials would you use?
  • Design, Build – Even though there is no such thing as perpetual motion, some inventor is working on the next machine to prove everyone was wrong. What are some of the obstacles to over come? How would you build your design?
  • Improve – Although the motion may not be “perpetual” there have been some big improvements in technologies that improve the performance of moving objects. What are some of the advancements in lubrication? How has friction being reduced?

That’s engineering

  • friction – the resistance between two surfaces as they move against each other. For example, the friction between the soles of your shoes and the floor is what prevents you from slipping and falling down.

Engineering ideas

  • first law of thermodynamics, second law of thermodynamics, friction, motion, perpetual, lubrication, indefinitely, energy

Do it
Here are some challenges for you to work on…

  • find and critiques same examples of perpetual motion machines

Learn more…