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2 Stars Orbiting each other

  1. Feb 23, 2009 #1
    Their are 2 stars orbiting one another. Their masses are equal. The speed at which they rotate is 220 km/h, and their orbital period is 14.4 days. Find the mass of the Star.

    2. Relevant equations
    220km/h = 61.1m/s
    14.4 days = 51840s

    V= 2pi(r)/T
    F= m4pi^2r/T^2

    Fg= Gm(star1)m(star2)/r^2

    These are all the equations I've been using. So far, using V= 2pi(r)/T I can deduce that the radius of the star is 504111.2m and using V=d/t I THINK I can say that the space between the stars is 3167424m, but Im not sure.
    I've also tried equating F=mv^2/r with Fg = Gm(star1)^2/r^2, and then found the mass to be 3.616x10^13. I don't think this is right, as my teacher said hint: The mass of the sun is 1.99*10^30 kg.
    I know I often make stupid math mistakes, but I can't seem to find out where I went wrong... Can anyone help me?
  2. jcsd
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