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Homework Help: Kind of Weird Orbital Problem

  1. Nov 7, 2006 #1
    Mars travels around the sun in 1.88 (earth) years, in an approximately circular orbit with radius 2.28 x 10^8 kilometers determine

    a)orbital speed of mars relative to sun
    b)mass of the sun..

    for part a) i did

    v= 2(pi)(r)/ T

    which i got 2(3.14)(2.28x10^11 meters)/ 5.93 x10^7 seconds

    v= 24145.7 m/s

    if thats correct, how do i calculate the mass of the sun
  2. jcsd
  3. Nov 7, 2006 #2


    User Avatar

    Have you done gravitational force?

    So you know that the force between them is

    F = Gm1m2/r^2

    And force also = mv^2/r where m is the mass of mars.

    If you equate them, I think you can solve for m1, the mass of the sun.
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