(a) Explain, on the basis of the Earth considered as a uniform sphere, why the numerical value of the acceleration due to gravity decreases
(i) when one moves to a point at a height h above the surface, and
(ii) when one moves to a point at a depth d below the surface.
(b) For the same numerical value of h and d (say, 10 km), state with reasons which change—at height or at depth—produces the greater decrease in the value of g.
(c) How would the answers to parts (a) and (b) be altered if the density of the Earth were to increase with depth? Explain qualitatively.