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. Then,
(a) the linear momentum of S remains constant in magnitude.
(b) the acceleration of S is always directed towards the centre of the earth.
(c) the angular momentum of S about The centre of the earth changes in direction, but its magnitude remains constant.
(d) the total mechanical energy of S varies periodically with time.
