1. Not finding help here? Sign up for a free 30min 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!

Need help-Energy of satellite

  1. Nov 26, 2007 #1
    1. The problem statement, all variables and given/known data
    msatellite = 6000 kg ;
    Mearth = 5:98 £ 1024 kg ;
    Rearth = 6:37 £ 106 m; and
    G = 6:67259 £ 10¡11 Nm2=kg2 :
    The radius of the satellite around the center
    of the Earth is r =13/2R.
    Hint: You may Find it useful to take into account that the gravitational force is a conservative force.
    Hint: The universal gravitational force law
    is F= GMm/r^2.

    Caution: Neglect the rotational kinetic energy due to the Earth's rotation.
    Find the energy required to launch a satellite from Earth into the circular orbit at the
    specified radius r =13/2R. Answer in units of J.

    2. Relevant equations
    F = GMm/r^2.

    U(gravitational) = GMm/r
    kinetic energy (translational) = 1/2mV^2 = (1/2GMm)/r

    3. The attempt at a solution

    Total energy = Kinetic + Ug = 0.5GMm/r - GMm/r = -2.8911e10 J
    but it is wrong
    please help
  2. jcsd
  3. Nov 26, 2007 #2
    maybe this will help as well

  4. Nov 26, 2007 #3
    i realized that for work = F*D, D is not r but r-R,earth because its launched from the surface of the earth, but i'm still getting a wrong answer
    please guys, i really could use some help
  5. Nov 26, 2007 #4
    okay, total energy should be K - Ug = .5GMm/r - GMm/r^2 but my answer is still wrong
    (i'm getting 2.8911e10)
  6. Nov 26, 2007 #5
    nvr mind, got the answer
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Need help-Energy of satellite
  1. Help needed on Energy (Replies: 2)