Answer: GM/R 2.
- A G/R<sup>2</sup>
- B GM/R<sup>2</sup>
- C GMm/R<sup>2</sup>
- D 2GM/R<sup>2</sup>
Correct answer: B. GM/R<sup>2</sup>
Explanation: Gravitational field intensity (force per unit mass) = GM/R<sup>2</sup> = g (acceleration due to gravity at surface).
g is maximum at Earth's surface; going up, it falls off as 1/r² (inverse-square); going down, it falls off linearly with depth (since only the mass enclosed within radius r contributes), reaching zero at the centre.
Concept context
Universal gravitation, orbital mechanics, gravitational potential, and escape velocity.