Conservation of angular momentum a spherical star with radius r -7.96 x 10 km and rotating with angular speed o -3.92 suddenly collapses into a neutron star. the neutron star emits a beam of x-rays directed outward that can be seen by an observatory on the carth r 4.55 x 104 km from the star beam sweeps past the earth with a tangential speed v 7.40 x 101s makes a full rotation. angular momentum was conserved during the collapse of the star. x 10-5 rad/s km/s each time the neutron star the moment of inertia of a solid sphere with mass m and radi us r about an axis through its center is mr 5 2 (a) use conservation of angular momentum to show that the radius of the neutron star r is gi ven by r 0) where ri, r, and o, and v are defined in the question. (b) calculate the radius of the neutron star. ( 1240 km) (c) how much time elapses between x-ray pulses detected by the observatory on the earth? ( 386 ms) v cor