Answer: Zero.
- A Maximum
- B 9.8 m/s<sup>2</sup>
- C 4.9 m/s<sup>2</sup>
- D Zero
Correct answer: D. Zero
Explanation: At Earth's center, gravitational pull from all surrounding mass cancels out. g = 0 at the center.
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.