Chapter Questions
Calculate the escape velocity (Unit 18 ) from a white dwarf and a neutron star. Assume that each has $1.4 \mathrm{M}_{\odot}$. Let the white dwarf's radius be $10^{4} \mathrm{km}$ and the neutron star's radius be $10 \mathrm{km}$.
Suppose a neutron star with a radius of $10^{4} \mathrm{km}$ is spinning with a period of 0.001 sec. How fast is its equator moving? Compare this speed to the neutron star's escape velocity calculated in problem 1.
The mass of a neutron is $1.67 \times 10^{-27}$ kg. How many neutrons are in a neutron star that has $1.4 \mathrm{M}_{\odot}$ ?
The volume of a neutron is about $10^{-45} \mathrm{m}^{3}$. Suppose you packed the number of neutrons you found in problem 2 into a sphere of radius $R$. The volume of a sphere is $4 / 3 \pi R^{3}$. What is $R$ in kilometers?
Suppose a neutron star is spinning with a period of 1.000 sec. If its radius shrinks by $1 \%$, what will its new period be?
Assuming that a $1.4-M_{\odot}$ pulsar has a radius of $10 \mathrm{km}$, calculate the acceleration due to gravity at the surface (see Unit 16 ). Compare this value to that of the Earth. How much would you weigh if you stood on this pulsar?