At depth d below Earth's surface, g' equals:
Ag (1 - d²/R²)
Bg (1 - d/R)
Cg (1 + d/R)
Dg (R/d)
Answer & Solution
Correct answer: B. g (1 - d/R)
For a uniform Earth, g' = g (1 - d/R). So g decreases linearly with depth, reaching zero at the centre (d = R).
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