Calculate the moment of inertia about a central axis (in units of kg m^2) for:
a. a solid sphere with a mass of 100 grams and a radius of 5.0cm.
b. a thin spherical shell with a mass of 100 grams and a radius of 5.0cm.
c. a solid cylinder with a mass of 100 grams and a radius of 5.0cm.
d. a thin hoop with a mass of 100 grams and a radius of 5.0cm.