Question

A neutron star of mass 4.0 x 1030kg has a radius of about 12km. Calculate its mean density . comment on the answer

Answer 1

Let's find the mean density of the neutron star:

$$\rho=\dfrac{m}{V}=\dfrac{m}{\dfrac{4}{3}\pi r^3},$$ $$\rho=\dfrac{4.0\cdot10^{30}\ kg}{\dfrac{4}{3}\pi\cdot(1.2\cdot10^4\ m)^3}=5.53\cdot10^{17}\ \dfrac{kg}{m^3}.$$

As we can see from calculations, the neutron star has an incredibly high density comparable to or greater than the density of an atomic nucleus.