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Acceleration of Space Shuttle at Lift Off

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  1. Nov 16, 2015 #1
    1. The problem statement, all variables and given/known data

    The mass of a space shuttle is approximately 2.0 x10^6 kg. If the thrust provides a force of 1.2 x 10^7 N, what is the acceleration of the space shuttle at lift off?
    6.0 m/s2
    0.06 m/s2
    1.67 m/s2
    0.167 m/s2

    2. Relevant equations
    Resultant force = thrust – weight
    Acceleration = resultant force ÷ mass


    3. The attempt at a solution
    Weight: 2.0 x10^6 kg*9.8=19600000
    Resultant Force: 1.2 x 10^7 N-19600000=-7600000
    Acceleration: -7600000/2.0 x10^6 kg= -3.8 m/s^2
    Not a choice and a negative acceleration
     
    Last edited: Nov 16, 2015
  2. jcsd
  3. Nov 16, 2015 #2

    berkeman

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    Staff: Mentor

    Welcome to the PF.

    Please show your work in detail so we can look for mistakes... :smile:
     
  4. Nov 16, 2015 #3

    SteamKing

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    That's because you were given incorrect data for the total thrust at take off.

    https://en.wikipedia.org/wiki/Space_Shuttle

    The Shuttle used 3 SSME (Space Shuttle Main Engines) which provide a total thrust of 5250 kN at sea level. In addition to these, there were two Solid Rocket Boosters (SRB) which provided a thrust of 12,500 kN each.
     
  5. Nov 16, 2015 #4
    That would be a total thrust of 30,250,000 N. Then you'd do 30,250,000N-19,600,000= 10,650,000 to get resultant force.
    The resultant force/mass would be: 10,650,000/2.0 x10^6 kg= 5.3 m/s^2. Right?? And that's not an answer choice.
     
  6. Nov 16, 2015 #5

    SteamKing

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    There's only one correct answer. There are infinitely many incorrect answers. :frown:

    I think whoever wrote this question wanted you to just divide the thrust value given in the problem by the mass of the shuttle to obtain an answer. It's just that this is one of the infinitely many incorrect answers.
     
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