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Homework Help: HELP:Periodic Motion/force

  1. Nov 16, 2004 #1
    1) An airplane caught in a storm, is forced in to a vertical periodic motion of period 30.2 seconds and amplitude 17.1 meters. The maximum force (in Newtons) acting on a passenger of mass {M} kG is?

    T=2pi/[sqrt of (max a*gravity)/A)] ---> max a = 0.07545 m/s^2 and F=ma but the mass of the passenger is not given. Can someone please help? Thanks.
     
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  3. Nov 16, 2004 #2

    Tom Mattson

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    It looks to me like your answer is supposed to be in terms of M.
     
  4. Nov 16, 2004 #3
    If the answer is in terms of m than the force is 0.07545M, where M=mass, right? but the correct answer is 976 Newtons.
     
  5. Nov 16, 2004 #4

    Tom Mattson

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    Right, but there doesn't seem to be enough information to get a single numerical value for the force. You can do an analysis on an individual passenger (Since you were asked for the force "on a passenger", I'm taking it to mean that you are looking for the normal force N):

    N-mg=ma
    N=mg+ma

    so...

    Nmax=mg+mamax.

    Then you can do an analysis on the airplane. I model it as a mass on a spring.

    kx-Mg=Ma
    (4π2M/T2)x-Mg=Ma

    so...

    amax=(4π2/T2)xmax

    You can substitute that expression for amax into the equation for Nmax, but without knowing the mass m of the passenger you can't get a numerical result.
     
  6. Nov 16, 2004 #5
    I don't get it either. There must be a way to find the force..... :cry:
     
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