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!

Calculate the magnitude of the angular momentum of the earth

  1. Feb 4, 2010 #1
    1. The problem statement, all variables and given/known data

    Calculate the magnitude of the angular momentum of the earth considered as a particle orbiting the sun. The mass of the earth is 5.97 x 10^24kg . Treat it as moving in a circular orbit of radius 1.50 x 10^11m at a speed of 2.98 x 10^4m/s

    3. The attempt at a solution

    I first try to find the moment of Inertia of the earth, I. I treated the earth as a solid sphere so

    I=2/5(5.97 x 10^24kg)(1.50 x 10^11m)^2

    = 5.373 x 10^46 kgm^2

    I then found the angular velocity of the earth by

    V=[tex]\omega[/tex]r

    2.98 x 10^4m/s/1.50 x 10^11m=[tex]\omega[/tex]

    [tex]\omega[/tex]=0.000000199 rad/sec

    Then

    L=I[tex]\omega[/tex]

    L=(5.373 x 10^46 kgm^2)(0.000000199 rad/sec)

    L=1.069227 x 10^40 kg*m^2/s ?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Feb 4, 2010 #2

    rl.bhat

    User Avatar
    Homework Helper

    I first try to find the moment of inertia of the earth, I. I treated the earth as a solid sphere so
    I=2/5(5.97 x 10^24kg)(1.50 x 10^11m)^2
    = 5.373 x 10^46 kgm^2

    It is wrong. Treat the earth as the particle
    And in the above calculation you have substituted for R the radius of the orbit, not the radius of the earth.
     
  4. Feb 4, 2010 #3

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The problem asks the orbital angular momentum of the earth, as a point mass. The moment of inertia with respect to the centre of mass should be neglected.

    By the way, you really think that the radius of Earth is 1.50 x 10^11 m ?

    ehild
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculate the magnitude of the angular momentum of the earth
Loading...