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Homework Help: Kinematic equation help

  1. Sep 14, 2007 #1
    1. The problem statement, all variables and given/known data

    A Rocket initially at rest on the ground accelerates straight upward from rest with constant net acceleration a, until time t_1 where fuel is exhausted.

    2. Relevant equations

    3. The attempt at a solution

    I thought that putting these values into the kinematic equation

    y = Vi(t) + 1/2*a*t^2 would be good but the answer is not 1/2(a)t^2 it is

    H = .5(a)t + (.5*a^2*t^2)/g
  2. jcsd
  3. Sep 14, 2007 #2

    Chi Meson

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    What is the problem asking for? Final height of the rocket? If so, remember that the rocket will still go up for a while after the fuel is exhausted, adding another distance to the one you have found. What's the initial velocity and what's the acceleration for the second part of this problem?
  4. Sep 14, 2007 #3

    yes it is asking for final height thank you I did not think of it still going up after running out of fuel I was thinking of it falling back down immediatly
  5. Sep 14, 2007 #4


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    see typo in red, now continue per Chi Meson's hint above.
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