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Homework Help: Friction, centripetal force, gravity, and velocity

  1. Feb 20, 2016 #1
    1. The problem statement, all variables and given/known data
    Rebecca goes on a popular ride at an amusement park that involves a cylinder rotating on a vertical axis, with a radius of 6.20 m. Rebecca stands inside, with her back against the wall of the cylinder. The ride rotates and presses Rebecca against the wall of the cylinder, and when she reaches a speed v, the floor of the ride drops so that she can no longer stand on it. The coefficient of static friction between the wall and Rebecca's clothing is 0.820. What should Rebecca's minimum speed v be when the floor is lowered, so that she does not fall?

    2. Relevant equations

    3. The attempt at a solution
    I've tried alot of different equations but none of them give me the right answer
    g = v2/r
    9.8 = v2/6.2
    60.76 = v2
    v = 7.79
    the correct answer is 8.61
  2. jcsd
  3. Feb 20, 2016 #2


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    Homework Helper
    Gold Member

    Draw an FBD showing all the forces acting on Rebecca's body. That way you can set up an equation with all the known quantities.
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