A rotating star collapses under the influence of gravitational forces to form a pulsar. The radius of the pulsar is 1.0 × 10⁻⁴ times the radius of the star before collapse. There is no change in mass. In both cases, the mass of the star is uniformly distributed in a spherical shape. Find the ratios of the 

(a) Angular momentum, 

(b) Angular velocity, and 

(c) Rotational kinetic energy of the star after collapse to the values before collapse. 

(d) If the period of the star's rotation before collapse is 1.0 × 107 s, what is its period after collapse?