Answer
The angular speed of the neutron star is 4600 rad/s.
Work Step by Step
We can use conservation of angular momentum to solve this question.
$L_2 = L_1$
$I_2\omega_2 = I_1\omega_1$
$(\frac{2}{5}mR_2^2)\omega_2=(\frac{2}{5}mR_1^2)\omega_1$
$\omega_2 = (\frac{R_1}{R_2})^2~\omega_1$
$\omega_2 = (\frac{7.0\times 10^5~km}{16~km})^2~[\frac{2\pi~rad}{(30~days)(24~hr/day)(3600~s/hr)}]$
$\omega_2 = 4600~rad/s$
The angular speed of the neutron star is 4600 rad/s.
