Question

A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth

• A. The acceleration of S is always directed towards the centre of earth
• B. The angular momentum of S about the centre of earth changes in direction, but its magnitudes remains constant
• C. The total mechanical energy of S varies periodically with time
• D. The linear momentum of S remains constant in magnitude.

Answer 1

The correct option is B

The angular momentum of S about the centre of earth changes in direction, but its magnitudes remains constant

Earth is considered to be at one focus of the elliptical orbit. Since the gravitational force experienced by the satellite is always directed towards the earth, its torque about earth is zero. Therefore, the angular momentum isconserved. Since gravitational field is a conservative field, the total mechanical energy is conserved although KE & PE independently vary with time