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Homework Help: Help with projectile motion-type question

  1. Jan 31, 2007 #1
    1. The problem statement, all variables and given/known data

    A 507.0 g model rocket is resting horizontally at the top edge of a 40.0 m high wall when it is accidentally bumped. The bump pushes it off the edge with a horizontal speed of 0.630 m/s and at the same time causes the engine to ignite. When the engine fires, it exerts a constant 24.1 N horizontal thrust away from the wall. How far from the base of the wall does the rocket land?

    I don't know where to start - I am not asking for the answer, just some direction on where to start...

    If anyone could help me on this, it would be fantastic. I am pretty much stumped! Thanks!
     
    Last edited: Jan 31, 2007
  2. jcsd
  3. Jan 31, 2007 #2
    well being a rocket nut I can't resist, but at the same time the problem is poorly stated IMO. I'm assuming the rocket engine is firing horizontal/edit never mind missed that part.

    (However that will not remain so, as the rocket "weathercocks" so the nose is pointed increasingly downward, but I doubt that is intended for consideration)

    so set up two velocities as a function of time: one in the x direction, given the initial velocity plus that acceleration privided by the motor and the other in the y. You can figure the time it hits the ground from the latter, ie a bullet shot horizontally from a rifle in theory should hit the ground at the same time as a bullet simply dropped from the height of the barrel. Does that help a little?
    John S
     
    Last edited: Jan 31, 2007
  4. Jan 31, 2007 #3
    How would you solve this if there was no rocket acceleration in the x?
     
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