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Homework Help: Maximum altitude of a rocket

  1. Sep 2, 2012 #1
    1. The problem statement, all variables and given/known data

    A rocket of mass 1.5 x 10^6 kg is launched upward from the surface of the Earth (mass ME = 5.97 x 10^24 kg, radius RE = 6.38 x 10^6 m) with a speed of 0.5 x 10^4 m/s. The rocket will reach a maximum altitude above the surface of the Earth of


    2. Relevant equations
    I thought I can solve it with the basic kinematic equations
    v^2=v0^2+2*a*delta(x)

    3. The attempt at a solution
    the right answer is 6.061*10^6m (according to the online quiz)
    but I can't reach that conclusion using the equation

    I'm not using the earth's radius or mass

    enlighten me plz
     
  2. jcsd
  3. Sep 2, 2012 #2

    rock.freak667

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    Homework Helper

    Try equating KE of rocket = PE of rocket above the earth's surface.
     
  4. Sep 2, 2012 #3

    CAF123

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    Gold Member

    You cannot assume a constant acceleration here. Equate the kinetic energy of the rocket at the surface of the earth with it's potential energy at a height [itex] h [/itex] above its surface.
     
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