This is a very simple yet powerful demonstration that shows how potential energy and kinetic energy transfer from one to the other and back again, over and over.  Once you wrap your head around this concept, you’ll be well on your way to designing world-class roller coasters.

For these experiments, find your materials:

  • some string
  • a bit of tape
  • a washer or a weight of some kind
  • set of magnets (at least 6, but more is better)
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26 Responses to “Pendulums”
  1. apbaine says:

    It is like the frequency experiment.I will probably like this experiment.


  2. Rxwill80 says:

    I can here it fine! the pendulum is kind of ok.

  3. Aurora says:

    Of course! Use anything for a weight that you have handy, like a rock.

  4. Linda Griffith says:

    can you use something other than a nut

  5. Ingrid Cordano says:


  6. Aurora says:

    Yes! That’s how generators work! They move magnets past a coil of wire, which causes a current to flow in the wire and can be used for all sorts of things! Great idea!

    You can make the motor generator project in Unit 11.

  7. Johanna Durrett says:

    We made the chaos pendulum and it is really cool. We were wondering if a machine based on this design (magnets and pendulum) could be used to generate electrical power. If not, why not?

  8. Aurora says:

    The pendulum hits the molecules in the air (mostly oxygen and nitrogen) which low down the pendulum. In space it would go forever since there aren’t many molecules to hit.

  9. jocelyn lin says:

    how does the air take away the power of the pendulim

  10. Aurora says:

    Centripetal (translation = “center-seeking” ) is the force needed to keep an object following a curved path. Objects will travel in a straight line unless they bump into something or have another force acting on it (gravity, drag force, etc.). If you swing a bucket around in a circle, you have to exert a pull on the handle to keep the bucket going around in a circle. If you let go, the bucket flies off in a straight line (initially) and then it moves under the influence of gravity and hits the ground. WHAM! Does that help?

  11. sheri albee says:

    What about centripical force?

  12. Aurora says:

    Yes, a pendulum swing would swing forever in a vacuum (no air resistance) if it also had a frictionless bearing (no energy lost due to friction) assuming that it’s on Earth, and no other forces other than gravity act on the pendulum. A pendulum swings back and forth because of gravity. If you’re far enough in space away from the influence of other objects like stars or planets or black holes, then your pendulum won’t swing – it will move in a straight line.

  13. sheri albee says:

    I mean swinged

  14. sheri albee says:

    If you swigged one of this in space would It go forever?

  15. Aurora says:

    The sound is working over here – what happens if you try a different computer?

  16. Anne Agah says:

    WHAT ABOUT speaking louder???

  17. Anne Agah says:

    oops-do you have any other suggestions?

    NOW thanks!

  18. Anne Agah says:

    We turned both speakers on but it still didn’t work

    thanks,Anne Agah

  19. Lisa West says:

    The chaos pendulum is wonderful. The kids have been experimenting with it all afternoon. I’m waiting for them to finish so i can play with it. 🙂

  20. Michelle Lindsey says:


  21. Aurora says:

    This video was recorded in mono by accident (don’t ask) – just turn up the volume on both speakers and you should be able to hear it fine. We’re working to fix this problem! 🙂

  22. Michelle Lindsey says:

    I cain’t get any sound for the chaus pendulum video what do i do

  23. Kellee Blauser says:

    Have you ever seen Astro Jax?
    kinda reminds me of a double pendulum.

  24. Debra Thomson says:

    When you wrapped the string around the pen, you made a simple machine!
    Holly Thomson 12

  25. Aurora says:

    Oops – sorry about that.. all fixed now.

  26. Anita Mullins says:

    The second video for “Chaos Pendulum” appears to not be available. Can you fix it?


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