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Homework Help: Rotor Ride at the State Fair

  1. Sep 17, 2014 #1
    1. The problem statement, all variables and given/known data

    In the Rotor Ride at the NM State Fair, passengers stand with their
    backs to the wall in a giant rotating drum with a radius of 10 feet. The drum
    is brought up to a speed of 33 1/3 RPM, and then the floor is lowered, leaving
    the passengers suspended above a giant hole in the floor, stuck to the wall by
    friction. The friction coefficient for the drum wall/clothing contact surface is
    typically s ' 0:3: Is this high enough to keep the passengers from sliding? How
    much can the angular speed be lowered before the passengers slide down into
    the hole?

    2. Relevant equations

    3. The attempt at a solution

    I don't see how we are supposed include the friction coefficient if there isn't a place for it in the equation. Perhaps I am not using the correct formula?
  2. jcsd
  3. Sep 17, 2014 #2


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    Homework Helper
    Gold Member

    Physics courses are not about simply plugging numbers into given equations. Rather, they are about logically thinking things through starting with a given set of principles (in this case, those principles are Newton's laws of motion, and static friction) and moving up from there. :smile:

    Anyway for this problem, you may wish to first start here: Consider a passenger with mass m on this ride. What is the normal force exerted by the drum's wall on this passenger?
  4. Sep 17, 2014 #3


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    Staff: Mentor

    You're not considering enough equations.

    There's more than one physics effect taking place here. Since the problem involves friction, what equation(s) do you know that pertain to it?

    Suggestion: When you are given a problem to solve, take a moment to evaluate the physics concepts that are implied then gather together your crib sheet of relevant equations. Here you've got rotational motion, friction, and gravity acting. You might need to draw a Free Body Diagram of the forces acting on a person subjected to the "Rotor".
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