Answer: 2g.
- A g/2
- B 2g
- C 4g
- D g
Correct answer: B. 2g
Explanation: g = (4/3)πGρR, so g ∝ R at constant density; doubling R gives 2g.
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.