Answer: Gravitational force.
- A Centrifugal force
- B Normal force
- C Gravitational force
- D Magnetic force
Correct answer: C. Gravitational force
Explanation: Earth's gravitational pull on the Moon provides the centripetal force to keep it in orbit.
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.