Came across this forum while searching the net for help. It's great to have a forum dedicated to physics. So hi to everyone :) Now to business. I'm stuck with this question. If you weigh 660N on the earth, what would you weigh on the surface of a neutron star that has the same mass as our sun and a diameter of 22.0km ? Take the mass of the sun to be m_s = 1.99×10^30kg, the gravitational constant to be G = 6.67×10^-11 N m^2/kg^2, and the acceleration due to gravity at the earth's surface to be g = 9.810 m/s^2. My working out: *r_n = radius of neutron *m_n = mass of neutron *m_me = mass of me r_n = 11000m m_n = 1.99 x 10^30kg m_me = w/g = 660/9.810 = 67.27828746kg = (G * m_n * m_me) / r_n^2 = (6.67x10^-11 * 1.99x10^30 * 67.27828746) / 11000^2 = 7.380205N ---- Now I'm told that the answer is wrong. So can someone tell me where I went wrong ? Thanks in advance.