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 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
Answer: a
(6)