Q. A satellite $S$ is moving in an elliptical orbit around 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 the earth
B) The angular momentum of $S$ about the centre of the earth changes in direction but its magnitude remains constant
C) The total mechanical energy of $S$ varies periodically with time
D) The linear momentum of $S$ remains constant in magnitude
Explanation
(a) When a satellite is moving in on elliptical orbit, it’s angular momentum ($= \overrightarrow{\mathbf{r}} \times \overrightarrow{\mathbf{p}}$) about the centre of earth dos not change its direction. The linear momentum ($= m\overrightarrow{\mathbf{v}}$) does not remain constant as velocity of satellite is not constant. The total mechanical energy of $S$ is constant at all locations.
The acceleration of $S$($=$centripetal acceleration) is always directed towards the centre of earth
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.