Answer: -GMm/r.
- A -GMm/r
- B GMm/r
- C -GMm/r<sup>2</sup>
- D mgh
Correct answer: A. -GMm/r
Explanation: Gravitational PE = -GMm/r. The negative sign indicates the body is in a bound (attractive) potential well.
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.