Which statement best describes the relationship between an object's density and its index of refraction?

a. as the mass per unit volume of the substance increases, the refraction index decreases.

b. as the optical density increases, the refraction index decreases.

c. as the physical density of the substance increases, the refraction index increases.

d. as the tendency of the atoms to absorb energy before reemitting it increases, the refraction index increases.

Arotating space station is said to create “artificial gravity”—a loosely-defined term used for an acceleration that would be crudely similar to gravity. the outer wall of the rotating space station would become a floor for the astronauts, and centripetal acceleration supplied by the floor would allow astronauts to exercise and maintain muscle and bone strength more naturally than in non-rotating space environments. if the space station is 200 m in diameter, what angular velocity would produce an “artificial gravity” of 9.80 m/s^{2} 2 at the rim?