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Uniform Circular Motion and centripetal force

  1. Nov 30, 2009 #1
    1. The problem statement, all variables and given/known data
    http://img.skitch.com/20091201-pxecs3d574itggpejybhdbp3qr.jpg

    Essentially, as an experiment, our physics class whirled a stopper attached to a string that went through a tube that was finally attached to a weight on the bottom of the string.

    3. The attempt at a solution
    I'm not really sure, unless the centripetal force is somehow not adequate to hold the weight up, but it should be, as long as the stopper is swung around quickly enough.. This seems contradictory to everything that we've learned about UCM this semester.
     
  2. jcsd
  3. Nov 30, 2009 #2

    rock.freak667

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    I think you need to show that a horizontal circle as show in the diagram is not physically possible?
     
  4. Dec 1, 2009 #3
    Oh yeah! Because if it was horizontal, there would be no "vertical tension" holding up the mass of the stopper?
     
  5. Dec 1, 2009 #4

    rock.freak667

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    yes

    Tsinθ=mg, θ=0, the mass will not stay in a horizontal circle.
     
  6. Dec 1, 2009 #5
    Ah, thanks. But why would it be "necessary for experimental precision?"
     
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