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Homework Help: Need help finding revolutions?

  1. Sep 22, 2009 #1
    1. The problem statement, all variables and given/known data

    As their booster rockets separate, Space Shuttle astronauts typically feel accelerations up to 3g, where g = 9.80 m/s2. In their training, astronauts ride in a device where they experience such an acceleration as a centripetal acceleration. Specifically, the astronaut is fastened securely at the end of a mechanical arm that then turns at constant speed in a horizontal circle. Determine the rotation rate, in revolutions per second, required to give an astronaut a centripetal acceleration of 2.89g while in circular motion with radius 9.46 m.

    2. Relevant equations

    radial(centripetal) acceleration= v^(2) / r

    v= 2(pi)(r) / T

    3. The attempt at a solution

    radial acc.= (9.8)(2.89)= 28.322 m/s^(s)

    28.322 m/s^(2) = v^(2) / 9.46m

    v= 16.368

    T= 2(pi)(9.46m) / (16.368) = 3.631

    Is that right???
  2. jcsd
  3. Sep 22, 2009 #2


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    Homework Helper

    you want to find the angular velocity ω. So use v=rω and find ω.

    Alternatively you could have used another expression for centripetal acceleration

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