1. The problem statement, all variables and given/known data The sun is a pretty typical star with a mass of 1.99x1030kg and a radius of 6.69x108 m. Since it isn't solid, it doesn't rotate uniformly, but has an average rotation rate of 1rev/25d. A star with a mass about about three times that of the Sun eventually explodes as a supernova and leaves behind its collapsed remnants - a neutron star or a black hole. Neutron stars masses are somewhat lower than the masses of the original stars, but have much smaller radii, less than 10 km. Newly-collapsed neutron stars emit beams of radio waves; since they rotate so quickly, the beams may intersect Earth at regular intervals. To produce the observed pulsar rates, the rotation rates must vary from 1rev/s to 1000rev/s. What would be the approximate rotation rate of the Sun if it became a neutron star with a radius of 10km? Assume it is spherical, with a uniform mass distribution, and that its moment of inertia if 0.059MR2 (Since it is not a solid you can not use I for a solid sphere). 2. Relevant equations I1ωo=I2ωf conservation of angular momentum ωavg = 1rev/25d ω0 = 1rev/(25x2x6.69x108m) = 2.99x10-11 rev/s I1=0.059(1.99x1030kg)(6.69x108m)2 I2 = 0.059(1.99x1030)(10m)2 ωf = ? 3. The attempt at a solution I used I1ωo=I2ωf and solved for ωf. After I solved for this I got 133,800rev. I then divided this final answer by 25d, or 25x2x10km since the suns radius is now that of a neutron star instead of it's original 6.69x108 m. This gave me a value of 267.7 rev/s, which according to the problem statement makes sense. I'm not exactly confident in my method though so I would like to know if this is correct.