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The Dzhanibekov Effect (Tennis Racket Effect)

Posted 2 months ago
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In this Wolfram blog post the bizarre behavior of rotating bodies was illustrated with some simulations. When I was writing the post I ended up simulating and replaying animations one time after another. It was almost addictive to watch what was going on, so I thought perhaps others would like to try it too.

In this post I have added the CAD files, as well as an additional model library so you can easily test the different objects yourself.

Instructions

Running in Mathematica

  • Open the notebook Modeling Surprising Physics.nb (the blog post with minor edits) in Mathematica
  • Evaluate the commands

Note that System Modeler is used for the animations, so when you evaluate these commands it will only work if you have System Modeler installed (otherwise you will get a message with a link to a page with info about System Modeler).

Running in System Modeler

  • Open the Modelica file DzhanibekovEffect.mo in System Modeler
  • Open the model DzhanibekovEffect.Examples.Space by double-clicking on it in the file class browser

System Modeler class browser

  • Click play (button) to simulate
  • Click animation (button) to animate
  • The second part of this video shows how you can edit parameters, simulate, and animate.

If you would like to simulate other objects you can change that in the model:

  • Right click on object and select "Replace component" and then to the component you want, e.g. the satellite

redeclare component

  • Now you can repeat the steps for simulation and animation above

Note that gravity is set to 0. If you want to change that or the initial velocities you can see how to do that in the video. For the satellite you probably want to change simulation time.

Have fun exploring!

2 Replies

If I change the 'g' from 0 to 9.8. I still see this effect. Shouldn't it is possible only when g =0.

I think you should still see it, even though it will be a disturbed version (as illustrated in the tennis racket example) where you add a constant acceleration in the direction of the gravity.

In a realistic case the object fall to the ground before you have time to see any pattern for it. By removing gravity you just make it a lot easier to observe the phenomena.

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