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Homework Help: Calculating Initial Acceleration

  1. Mar 21, 2013 #1
    calculate the initial acceleration of a 13 140 kg V-2 rocket bomb fired vertically, if the thrust of its engines is 2.63 x 10 to the power of 5 N. then calculate the rockets acceleration near "burn-out", when its mass is only 4170 kg.

    So i did. Part 1.

    Fnet = ma
    a = fnet/m
    20.01m/s^2= 263000/13140

    but the correct answer is 10.2
  2. jcsd
  3. Mar 21, 2013 #2

    rude man

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    Homework Helper
    Gold Member

    You forgot to include gravitational force.
  4. Mar 21, 2013 #3
    ah, right right.
    Fg = 13140+9.8
    =128772 N (Down)

    Fnet= 263000-128772
    = 134228 N (Up)

    Acceleration= f/m
    =10.2m/s^2 (Up)

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