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Homework Help: Momentum. resulting velocity. Rocket

  1. Mar 9, 2008 #1
    [SOLVED] Momentum. resulting velocity. Rocket

    1. The problem statement, all variables and given/known data

    On earth, an astronaut and equipment weigh 1,960.0 N. While weightless in space, the astronaut fires a 100 N rocket backpack for 2.0 s. What is the resulting velocity of the astronaut and equipment?

    I have to be missing something. I tried using every formula given to me in class and I cannot get anywhere. Please help. Thanks.

    2. Relevant equations

    Ft= (mf)(vf)-(mi)(vi)
    Ft=ma+v(difference of m/t)

    3. The attempt at a solution
    I tried a few and can't get a relevant answer. I really do not know where to begin with the rocket.
    Last edited: Mar 9, 2008
  2. jcsd
  3. Mar 9, 2008 #2


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    Don't worry about the rocket itself. You only care about what it does. It applies a constant force over a specified time? How does this affect the astronaut in terms of momentum?
  4. Mar 9, 2008 #3
    difference of momentum= (100N)(2.0s) = 200kgm/s

    200kgm/s= (1960N/ 9.8m/s^2) V


    I first found the difference of momentum which is force * time. then used the equation momentum=mass*velocity. Is this correct?
  5. Mar 10, 2008 #4


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    Looks Good!:smile:
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