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Homework Help: Projectile motion rocket problem

  1. Sep 11, 2007 #1
    1. The problem statement, all variables and given/known data
    A rocket is fired at at speed fo 75.0 m/s from ground level, at an angle of 60.0 deg. above the horizontal. The rocket is fired toward an 11.0 m high wall, shich is located 27.0 m away. The rocket attains its launch speed in a negligibly short period of time, after which its engines shut down and the rocket coasts. By how much does the rocket clear the top of the wall?

    2. Relevant equations

    3. The attempt at a solution
    I got the initial vy by 75.0(sin(60))=65.0 m/s, and vx 75.0(cos(60))=37.5 m/s
    27.0m=(37.5m/s)t + (1/2*0*t)
    y=65.0 m/s(0.720s) + 1/2(9.80 m/s^2)(0.720^2)
    49.3-11.0=38.3m above the wall
    The answer is supposed to be 33.2m, I'm not sure where I went wrong.
  2. jcsd
  3. Sep 11, 2007 #2


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    Homework Helper

    vertical acceleration = -9.8m/s^2 not 9.8m/s^2
  4. Sep 11, 2007 #3
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