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Homework Help: Shuttle moving in a circular orbit

  1. Mar 10, 2013 #1
    The space shuttle is moving in a circular orbit with a speed of 7.8km/s and a period of 87min. In order to return Earth, the shuttle fires its retro engines opposite to its direction of motion. The engine provide a deceleration of 6m/s^2 that is constant in magnitude and direction. What is the total acceleration of the shuttle?

    can't seem to understand how to start solving it. don't i need the radius of orbit?
  2. jcsd
  3. Mar 10, 2013 #2
    Yes. Use the universal law of gravitation to solve radius of the orbit.
  4. Mar 10, 2013 #3
    i tried to solve it but im not sure if it is correct.

    r=113100m = 113,1km
    a = v^2/r = ω^2r (circular motion equations)
    (2/29)^2x113,1=78/145 km/sec^2 = 15600/29 m/sec^2

    the retro engine deceleration is 6m/sec^2
    15600/29-6=15426/29 m/sec^2

    is it correct? i really need help, confirmation on this.
  5. Mar 10, 2013 #4
    gravitation law requires masses if am not mistaken and also i think this is a circular motion question.
  6. Mar 10, 2013 #5
    Satellite mass will cancel out.
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