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Homework Help: The 1000 kg Rocket (the RIGHT problem)

  1. Aug 30, 2008 #1
    1. The problem statement, all variables and given/known data

    A 1000 kg weather rocket is launched straight up. The rocket motor provides a constant acceleration for 12 seconds, then the motor stops. The rocket reaches a maximum altitude 36 seconds after motors exhaust all the fuel. You can ignore any effects of air resistance. (It will help if you draw a vertical motion map and v vs. t graph for this case.)

    (a) What is the total flight time to reach maximum altitude?
    48 seconds
    (b) What is the rocket's maximum speed?

    (c) What was the rocket's acceleration during the first 12 s?

    (d)What maximum altitude did the rocket reach?

    2. Relevant equations
    X=V0t +.5at^2
    Vf^2= V0^2 + 2ax

    3. The attempt at a solution

    I've already discovered the time. (Obviously by just adding the two times together). But I've no idea how to do the rest of the problem. I've drawn all the graphs (position, velocity, acceleration) but nothing visual seems to help either. The motion diagram isn't doing much for me too. It seems that I'd need velocity to do the other problems, but I can't even figure that out. Any suggestions?

  2. jcsd
  3. Aug 30, 2008 #2

    [tex]Acceleration\ due\ to\ gravity=-10 ms^{-2}[/tex]

    Look at the time when the rocket stops propelling itself, and the time its velocity is zero, then it should click :)
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