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Projectile Motion(Rocket)

  1. Feb 15, 2013 #1
    1. The problem statement, all variables and given/known data

    When it is 145 m above the ground, a rocket traveling vertically upward at a constant 8.50 m/s relative to the ground launches a secondary rocket at a speed of 12 m/s at an angle of 53 degrees above the horizontal, both quantities being measured by an astronaut sitting in the rocket. Air resistance is too small to worry about.

    (a) Just as the secondary rocket is launched, what are the horizontal and vertical components of its velocity relative to (i) the astronaut sitting in the rocket and (ii) Mission Control on the ground?

    (b) Find the initial speed and launch angle of the secondary rocket as measured by mission control.

    (c) What maximum height above the ground does the secondary rocket reach?



    2. Relevant equations

    Vy=Vosin(θ)
    Vx=Vocos(θ)

    Vr2/e=Vr2/r1+Vr1/e

    Vr2/e= velocity of rocket 2 relative to earth
    Vr2/r1= velocity of rocket 2 relative to rocket 1
    Vr1/e= velocity of rocket 1 relative to earth

    3. The attempt at a solution
    A)
    i:
    Vr2/r1-x= 12m/s*cos(53)=7.2217 m/s
    Vr2/r1-y= 12m/s*sin(53)=9.5836 m/s

    Vr2/e=vr2/r1 + vr1/e

    ii: Vr2/e-y=vr2/r1-y + vr1/e-y
    Vr2/3-y= 9.5836 m/s + 8.50m/s=18.0836m/s

    Vr2/e-x=vr2/r1-x + vr1/e-x
    vr2/e-x= 7.2217m/s + 0=7.2217m/s

    Do I have part a right so far? thanks!
     
  2. jcsd
  3. Feb 15, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks good to me!
     
  4. Feb 15, 2013 #3
    Thank you Doctor!!!
     
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