A star having an initial radius of 1.00 x 10^8 m and period of 30 days collapses all of a sudden to a radius of 1.00 x 10^4 m.
(i) Determine the period of rotation after collapse.
(ii) Determine the work done by gravity throughout the collapse when the mass of the star is around 2.00 x 1030 kg. (The only force doing work on the system is gravitation; therefore the work done by gravitation is the change in kinetic energy of the star).
(iii) Determine the speed of an indestructible person standing on the equator of the collapsed star? (Avoid any relativistic or thermal effects and suppose the star is spherical before and after it collapses).