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Homework Help: YoYo challenge help

  1. Nov 18, 2006 #1
    Hey guys! I have an assignment similar to this:


    I dont really know how to go about building this. From looking at the nesessary equations (moment of inertia, etc.) it seems to me that the performance of the yoyo in this task is reliant upon the radius and mass of the yoyo. I'm pretty sure a larger radius will be beneficial, but im not too sure about the mass. (we have not covered rotational motion yet so i am not an expert on how this kind of yoyo works)

    I'm also not sure about what materials i should use to construct it, given that i cannot use parts of other yoyos, and they should be fairly cheap.

    Any suggestions are very much appreciated...im not looking for anyone to solve the whole thing for me, just further insight into how this kind of yoyo works and how i can use this knowledge to go about building it.

  2. jcsd
  3. Nov 18, 2006 #2
    Like the article says, the best teams had more mass distribution in the periphery of the object, meaning that it simulated the properties of a thin ring. Since you now have to take into account that energy conservation applies not only to kinetic energy in the form of 1/2*M*v^2 but to rotational kinetic energy in the form of 1/2*I*(omega)^2. So you need more rotational energy at the bottom so that the yo-yo "crawls" its way back up. Essentially the more moment of inertia that the yo-yo has the more power it has to go back up to its original starting point. At least this is what I believe would happen in this situation, if I'm wrong and someone sees please correct me.
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