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Homework Help: Rocket propulsion

  1. Feb 3, 2005 #1
    A large rocket with an exhaust speed of v=3000m/s develops a thrust of 24 million Newton.
    a. How much mass is being blasted out of the rocket exhaust per second and
    b. what is the max speed the rocket can attain if it starts from rest in a force-free environment with v=3000m/s and if 90% of its initial mass is fuel and oxidizer?

    a. 8 thousand kg (=24mill/3000)
    b. I'm not sure what the question is asking at all
  2. jcsd
  3. Feb 3, 2005 #2


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    Another way to phrase the question would be - if the rocket is 90% fuel mass, then what is its final speed (ignoring gravity)?
  4. Feb 3, 2005 #3
    but dont I need the original mass?
  5. Feb 4, 2005 #4


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    b) Initial and final masses only appear as a ratio in the expression for the rocket velocity.
    Find the way in which that ratio appears in the velocity expression.
    Last edited: Feb 4, 2005
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