Consider a satellite orbiting the Earth in a stable circular orbit at a constant altitude. Which of the following physical quantities associated with the satellite remains conserved throughout its motion under the central gravitational force?

💡 Solution & Explanation

Angular momentum about the center of the Earth remains conserved because the gravitational force acting on the satellite is a central force directed along the line joining the centers of the Earth and the satellite, resulting in a zero net torque. While kinetic and potential energies are constantly interchanged during elliptical orbits, they remain individually constant only in perfectly circular orbits, whereas angular momentum is invariant for any central force motion. Kepler second law of planetary motion is a direct consequence of this conservation of angular momentum.