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Homework Help: Airplane turning

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data
    A supersonic airplane is flying horizontally at a speed of 2840 km/h. What is the centripetal acceleration of the airplane, if it turns from North to East on a circular path with a radius of 86.5 km?
    How much time does the turn take?
    How much distance does the airplane cover during the turn?


    2. Relevant equations
    a = v^2/r


    3. The attempt at a solution
    I got the acceleration which = 7.9 m/s but for calculating the time can I use Wf = Wo + at and use 90 degree for the initial and 0 for the final to solve for t
     
  2. jcsd
  3. Sep 30, 2007 #2
    No I think you need to use:
    [tex]v=\frac{2R \pi}{T}[/tex]

    where T is the time to make 1 rotation, in your problem the plane doesn't make a full rotation so the T you need will be a fraction of the original T depending on how much of a rotation the plane makes
     
  4. Sep 30, 2007 #3
    I am getting a really large number, 688.94 s, that doesn't seem logical?
    I did...
    (2 * 86500m * pi)/788.89 m/s
     
  5. Sep 30, 2007 #4
    well that's to make 1 full rotation but the plane doesn't make a full rotation.
    from N to E is how many degree's? or what fraction of the entire x-y plane?
    take that fraction and multiply that time by it and you'll get the time to make just that part of the rotation.
     
  6. Sep 30, 2007 #5
    Oh okay so thats for a full revolution ok I got it then, just multiply by 1/4. Thank you.
     
  7. Sep 30, 2007 #6
    okay so for the third part of the question to find the distance can we use...
    W = (2pi/T) * (1/4)
    W = Change in theta/Change in time
     
  8. Sep 30, 2007 #7
    Hm..well if the plane travel's 1/4 of the circular path that should be 1/4 of the diameter of the circle?

    I've never seen those equations you're using but I've just learned circular motion from the book so far until Tuesday.
     
  9. Sep 30, 2007 #8
    I just tried 1/4 of the diameter but it says incorrect :( I don't know what to use.
     
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