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What is this thing

  1. Aug 13, 2012 #1
    i have no idea whats the point of this if u help me i would relay be thank full

    http://imgit.me/i/3K7P0W0.jpeg [Broken]

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  2. jcsd
  3. Aug 13, 2012 #2


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    I have never seen one like that but it looks, to me, like a click click click toy, rather like a Newton's Cradle (balls suspended on strings from a frame). You pull one ball up the slope on one side and release it. Because the balls have identical masses, when it hits the other ball, it stops dead and the other one goes off with the same velocity - because the Momentum is transferred from one to the other. There is more friction with this toy than with the Newton's cradle so the movement will die out a bit quicker but it should carry on for a dozen collisions or more before it stops. You need the slot to be clean (polished) for best results and the whole thing should be level, I should think.
  4. Aug 13, 2012 #3
    thanks man i appreciate it ur cool
  5. Aug 13, 2012 #4
    tho surprisingly when i do what u said the balls stick together and move as one until they stop
  6. Aug 13, 2012 #5


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    Unlike in Newton's Cradle these balls are rolling. They have significant angular momentum too, which not transferred fully on collision (and if it was, it would have the wrong direction to make the other ball roll).

    It looks like a part of a huge ring shaped ball-bearing. Adjustable wind turbine blades have bearings with balls of about this size.
  7. Aug 13, 2012 #6


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    That track looks like polished wood to me, though.
    But yes, the issue with angular momentum would be yet another mechanism for energy loss and slow the oscillations down quicker, though. It would not be hard for someone with the time and inclination to work out the proportion of linear vs angular momentum - which could suggest some ballpark figures for including the rolling. The degree of friction between balls and ball-on-track would affect the details a bit though.
    It's definitely not as 'ideal' as Newton's cradle.
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