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Centripetal force speed

  1. Sep 30, 2009 #1
    1. The problem statement, all variables and given/known data

    A) An amusement park ride consists of a rotating
    circular platform 10.8 m in diameter from
    which 10 kg seats are suspended at the end
    of 2.34 m massless chains. When the system
    rotates, the chains make an angle of 29.4◦ with
    the vertical.
    The acceleration of gravity is 9.8 m/s2 .

    What is the speed of each seat?
    Answer in units of m/s.

    B) If a child of mass 42.6 kg sits in a seat, what is
    the tension in the chain (for the same angle)?
    Answer in units of N.

    2. Relevant equations

    ∑F=ma_(c)= m (v^2/r)



    3. The attempt at a solution

    If this where talking about the string starting from origin of pole, wouldn't be that hard. But since they added the top diameter, I am not sure how to tackle this problem.
     
  2. jcsd
  3. Sep 30, 2009 #2

    Doc Al

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    Staff: Mentor

    The chains are attached to the edge of the circular platform and angle outward as the entire thing rotates. The axis of rotation is the center of the platform.
     
  4. Sep 30, 2009 #3
    I am aware of this, but from what my book has and what I have been trying to find out, I can't seem to figure out where to start since I have to factor in the radius of the axle the chains are attached to. Which is where I am stuck trying to figure out how to start.
     
  5. Sep 30, 2009 #4

    Doc Al

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    Staff: Mentor

    Do you have a diagram to work from? I'm not sure what you mean by "radius of the axle". You certainly have to add the radius of the platform to any calculation, but that's given. And you know the angle that the chains make, so you can figure out how much they add to the total radius.
     
  6. Sep 30, 2009 #5
    Here is a diagram :

    http://img525.imageshack.us/img525/7149/captureni.jpg" [Broken]
     
    Last edited by a moderator: May 4, 2017
  7. Sep 30, 2009 #6

    Doc Al

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    Staff: Mentor

    Good. So what's the issue? Can you calculate the radius of the circular path of the chairs?
     
  8. Sep 30, 2009 #7
    Yes, it is the diameter of 10.8 plus the 2.34sin(29.4) then divide by 2 to find radius, but I am still trying to find relations to get from not having a time and not having a velocity to finding them.
     
  9. Sep 30, 2009 #8

    Doc Al

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    Staff: Mentor

    Analyze the forces acting on the chairs and apply Newton's 2nd law. (Consider vertical and horizontal components.)
     
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