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Homework Help: Centripetal force ball on a string lab

  1. Nov 17, 2016 #1
    1. The problem statement, all variables and given/known data
    So referring to this lab , http://static3.mbtfiles.co.uk/media...ureate/physics/824297/html/images/image12.png

    In this lab you are holding the plastic tube and twirling it to make the small mass spin in a circle. Keep in mind there is a mass on the bottom.

    I have to create an expression for Fc with theta and radius.

    2. Relevant equations

    Fc = 4pi^2rf^2 * m
    3. The attempt at a solution
    Well from the FBD of the small mass, we know that FC = FT

    and from the FBD of the mass at the bottom we know that FT=FG.

    Therefore for the system, wouldn't FC = FG of the mass on the bottom?

    As for the equation i am not really sure were to start, could someone help me out please.
  2. jcsd
  3. Nov 17, 2016 #2


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    Homework Helper

    The string attached tot the mass going in a circle is angled downwards a bit, that is the horizontal plane in which the mass is circling is a bit below the top of the tube. That is the theta that is mentioned. Best to draw a diagram and post it.
  4. Nov 17, 2016 #3
    so i know the lab looks something like this, and the Fg of the small mass will cancel out the fty in the tension, therefore ftx controlling the motion.

    Attached Files:

    • lab.png
      File size:
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  5. Nov 17, 2016 #4


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    Homework Helper

    Yes, the x component provides the centripetal force.
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