prove that the distance we have to cover into the earth below its surface is twice the distance we have to cover above the surface to get the same change in g.

value of g below the earth surface g= g'(1- d/R) -----------(1)

value of g above the earth surface g= g'(1-2h/R) ---------(2)

from (1) nd (2)

= g'(1- d/R) = g'(1-2h/R)

= d=2h

hence the distance to cover below the earth surface is equal to twice the distance above the earth surface to get same change in g....

hope this helps u!!!!!