Chapter 9, Problem 47P

Neutron star An extremely dense neutron star with mass equal to that of the Sun has a radius of about 10 km—about the sue of Manhattan island. These stars are thought to route once about their axis every 0.03 to 4 s. depending on their size and mass. Suppose that the neutron star described in the first sentence rotates once every 0.040 s. If its volume then expanded to occupy a uniform sphere of radius $1.4\times {10}^8$ m (most of the Sun's mass is in a sphere of this size) with no change in mass or rotational momentum, what time interval would be required for one rotaton? By comparison, the Sun rotates once about its axis each month.