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Homework Help: A Rocket

  1. Dec 10, 2009 #1
    1. The problem statement, all variables and given/known data
    A Saturn V rocket has a mass of 2.75x10^6 Kg and exerts a force of 3.3x10^6N on the gases it expels.
    determine the initial vertical acceleration of the rocket.



    2. The attempt at a solution
    heres my attempt...
    F=3.3x10^6N
    Fg=
    M=2.75x10^6
    Fnet-MA
    F-Fg=ma
    F-mg=ma
    3.3x10^6-(2.75x10^6)(9.8)=2.75x10^6a
    3.3x10^6-2.6x10^7=2.75x10^6a
    -2.2x10^7=2.75x10^6a
    -2.2x10^7/2.75x10^6=a
    a=-8

    The accual answer is 2.2m/s^2
    Can someone explain to me what i got wrong?
     
  2. jcsd
  3. Dec 10, 2009 #2

    ideasrule

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    Are you sure it's 3.3x10^6N and not 3.3*10^7 N? You get the correct answer with 3.3*10^7 N.
     
  4. Dec 10, 2009 #3
    No im sure its that
    this question is straight from a text book.
     
  5. Dec 10, 2009 #4

    ideasrule

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    Homework Helper

    In that case, the textbook made a mistake.
     
  6. Dec 10, 2009 #5
    It must have!
     
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