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Homework Help: Given the mass of a star, determine Kepler's constant.

  1. Apr 28, 2009 #1
    1. The problem statement, all variables and given/known data
    "The mass of a star is 4.85x10^29kg. In scientific notation, Kepler's constant for that star is bx10^w s2/m3. the value of b is_____."

    2. Relevant equations


    3. The attempt at a solution
    This problem is very tough. I first assumed that K would be 0 because the star has no satellites, and therefore is experiencing linear motion, not circular motion. To my dismay however, the answer is indeed 3 digits and Kstar> 0.
    The greatest obstacle is how am I to derive the period and semi major axis of its orbit, if i am only given the star's mass???!!!
    Any insights into this problem are helpful.
  2. jcsd
  3. Apr 29, 2009 #2


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    Homework Helper

    Welcome to PF.

    If K = T2/ a3

    Can't you determine K directly from:

    T = 2π*(a3/GM)1/2


    K = 4π2/(G*M)
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