1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: 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



    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
    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!!!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook