Thursday, January 22, 2015

newtonian mechanics - Intuitive Explanation of Tippe Top Effect?


A friend showed me a tippe top (a special kind of spinning top) lately and asked me about the physics behind it. I thought about it for a while but cannot quite figure it out. So I will throw the question to SE. Below is a picture of tippe top:


                                       Tippy-top


So basically the strange effect is that when you spin such a top fast enough with its round surface touching the table, the top will wobble and eventually invert itself. There is a video of this effect at wiki commons and here is an illustrative picture:


                        Tippy-top turning upside-down


So my questions are:



  1. Why is the top so unstable? Why does it invert?

  2. Why does the initial angular velocity of the top matter? (Why do we have to spin faster than a certain velocity in order for the top to invert?)


  3. What other shapes will lead to inversion?


I am looking for some intuitive explanations that do not involve too much mathematics. Heuristic approaches are welcomed!




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