For small depths, the acceleration due to gravity decreases nearly linearly with depth.
(i) Taking g=9.8m s−2 and R=6.4×106m, calculate the values of g at depths 0km, 200km, 400km and 800km.
(ii) On a set of axes with depth on the horizontal axis and g on the vertical axis, plot the four points obtained in (i) and draw a smooth curve through them.
(iii) From your graph or otherwise, estimate the depth at which g falls to 9.0m s−2.