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Homework Help: Understanding rocket motion

  1. Dec 14, 2009 #1
    Hi there
    I'm having a bit trouble understanding the rocket motion and how the find the velocity, acceleration and travelheight as a function of time.
    First, i assume that the velocity of the ejected mass relative to the rocket is constant. Secondly, i assume that the rocket mass changes with a constant rate. I'm working with the motion in a single dimension.

    I have derived the rocket motion equation considering the acceleration of the rocket to be:


    where vr is the velocity of the rocket, ve is the exhaust velocity, Mr is the mass of the rocket and dM/dt is the change in mass over the interval dt.

    So - how do i find:

    The velocity as a function of time
    The acceleration as a function of time
    The travelheight as a function of time
  2. jcsd
  3. Dec 14, 2009 #2
    For vertical motion you'll need to account for changing weight w = -mg and the drag, and then if the engine burn is short consider the momentum during coasting flight.. Start here and be sure to visit the NASA link included:

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