Chapter 1, Problem 40AP

In a neutron star, gravity causes the electrons to combine with protons to form neutrons. A typical neutron star has a mass half that of the sun, compressed into a sphere of radius 20 km. If such a neutron star contains $\text{6}.0\times \text{1}{0}^{\text{56}}$ neutrons, calculate its density in grams per cubic centimeter. Compare this with the density inside a ${}^{\text{232}}\text{Th}$ nucleus, in which 142 neutrons and 90 protons occupy a sphere of radius $\text{9}.\text{1}\times \text{1}{0}^{-\text{13}}\text{cm}$ . Take the mass of a neutron to be $\text{1}.\text{675}\times \text{1}{0}^{-\text{24}}\text{g}$ and that of a proton to be $\text{1}.\text{673}\times \text{1}{0}^{-\text{24}}\text{g}$ .