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Early test flights for the space shuttle used a glider

  1. Apr 5, 2009 #1
    1. The problem statement, all variables and given/known data
    Early test flights for the space shuttle used a "glider" (mass of 940 kg including pilot). After a horizontal launch at 470 km/h at a height of 4000 m, the glider eventually landed at a speed of 210 km/h . What would its landing speed have been in the absence of air resistance(in km/h)? What was the average force of air resistance exerted on it if it came in at a constant glide angle of 15 degrees to the Earth's surface?

    2. Relevant equations
    Ki + Ui = Kf + Uf
    .5mv[tex]^{2}[/tex]+mgh=.5mv[tex]^{2}[/tex]

    3. The attempt at a solution
    I'm not so sure about the second question but here's what I did for the first one.
    I changed the units so that the answer would be in km/h.
    g=35.28 km/h
    h=4 km
    v[tex]^{2}[/tex]=[2(.5mv[tex]^{2}[/tex]+mgh)]/m
    v[tex]^{2}[/tex]=[2(.5(940)(470)[tex]^{2}[/tex]+(940)(35.28)(4)]=221182.24
    v=470km/h
    Unfortunately, this answer is incorrect. Any help would be greatly appreciated.
     
  2. jcsd
  3. Apr 5, 2009 #2
    Re: Glider

    g is acceleration? The units could be kilometers per hour squared, rather than kilometers per hour.
     
  4. Apr 5, 2009 #3

    rl.bhat

    User Avatar
    Homework Helper

    Re: Glider

    In the absence of air resistance, the horizontal velocity will remain as it is.
    Find its velocity when if falls through 4 km. The resultant of this velocity and the horizontal velocity will give the landing velocity.
     
  5. Apr 5, 2009 #4
    Re: Glider

    Thanks. I got the first part. As for the second question, I'm not quite sure how to go about it. I think I'm suppose to use F=ma. So I caculated the acceleration.
    a=(v[tex]^{2}[/tex]-v[tex]^{2}_{0}[/tex])/(2x)
    a=(210[tex]^{2}[/tex]-470[tex]^{2}[/tex])/((2)(4))=-22100

    F=ma=(940)(-22100)=-2077400

    But that only gets me the force of the gilder and doesn't include friction. I was also thinking that I should get the sum of forces.So
    F[tex]_{gilder}[/tex]-F[tex]_{friction}[/tex]=ma
    I don't think that's quite right either. There suppose to be a 15 degree angle but I don't know where it goes. Can somebody help me?
     
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