Answer: 24 hours.
- A 12 hours
- B 24 hours
- C 36 hours
- D 48 hours
Correct answer: B. 24 hours
Explanation: Geostationary satellites have T = 24 hours (same as Earth's rotation), so they appear stationary over the equator.
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.