1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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:

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook