Answer: mgh.
- A mgh
- B mg/h
- C mh/g
- D -mgh
Correct answer: A. mgh
Explanation: Near Earth's surface, gravitational PE = mgh (taking surface as reference, PE is positive above it).
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.