11.3 Exercise 9

The Sun’s mass is $2.0 \times 10^{30} \text{kg},$ its radius is $7.0 \times 10^{5} \text{km},$ and it has a rotational period of approximately 28 days. If the Sun should collapse into a white dwarf of radius $3.5 \times 10^{3} \text{km},$ what would its period be if no mass were ejected and a sphere of uniform density can model the Sun both before and after?