Monday, July 14, 2014

Rotational Instability in Pictures and Code

You might remember one of my G+ posts[2] from a few months ago, about a video wherein a Soviet astronaut spun a small wingnut,



OK, so not the Teenage Mutant Ninja Turtles character, an actual wingnut[3]:


+Bruce Elliott pointed out in a comment to the original post, (see below), that rotating an object, like a book, about its intermediate axis, (an axis parallel to the bottom edge of the cover), will cause unstable rotation.

Now, Brian Weinstein of The Fouriest Series[1] has posted a mathematica demo complete with gifs of the rotating book.  On top of that, he includes a link to a gist that contains the Mathematica code[4] for creating the rotation demo.

Here's the rotating book image from Brian's page, which I'd advise following if you enjoy mathy gifs!


G+ post mentioned above



References:
1.  Awesome intermediate rotation page
http://fouriestseries.tumblr.com/post/91685028535/rotational-stability

2.  G+ post
https://plus.google.com/108242372478733707643/posts/KxN4Dj55a7E

3.  Wingnut video
http://youtu.be/dL6Pt1O_gSE

4.  Mathematica code gist
https://gist.github.com/BrianWeinstein/6a8a852c46053c0c8d7d

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