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Weight on a neutron star ( universal gravity)

  1. Mar 10, 2009 #1
    1. The problem statement, all variables and given/known data

    Neutron stars, such as the one at the center of the Crab Nebula, have about the same mass as our sun but a much smaller diameter.

    If you weigh 650 N on the earth, what would be your weight on the surface of a neutron star that has the same mass as our sun and a diameter of 15.0 km ?

    Take the mass of the sun to be = 1.99×1030 kg , the gravitational constant to be
    G = 6.67×10−11 , and the acceleration due to gravity at the earth's surface to be
    g = 9.810 .

    Express your weight W_star in newtons.

    2. Relevant equations

    F = GMm/r^2

    3. The attempt at a solution

    mg = w
    mg = 650
    m = 650/g = 650 / 9.810 = mass of you

    F = GMm/r^2

    ma = GMm/r^2

    a = GM/r^2 = acceleration in the neutron star.

    F = ma;

    = Mass of you * acceleration in neutron star

    where

    acceleration in neutron star =

    [ 6.67 * 10^-11 * 1.99 * 10^30 ] / r^2--(or D/2)^2

    =

    6.67 * 10^-11 * 1.99*10^30 / 7500^2
    ~ 3.527 x 10^12


    so

    w = mg
    = 650/9.81 * (3.527 * 10^12)

    is this right, can you check my calculation?
     
  2. jcsd
  3. Mar 10, 2009 #2
    I got it, thanks fooorrrr alll yoouuuurrrrr heeeellllppppp guuuuuuyyyysss
    (cough*sarcasm*cough).
     
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