Q. A spacecraft consume more fuel in going from earth to moon than it does on the return trip. Comment on this .
Ans. In going from earth to moon, the spacecraft has to do more work against the greater gravitational attraction of the earth. For the return journey, moon’s gravitational force is much less, hence less work is done and less fuel is consumed.
Q. Can a satellite be in an orbit in a plane not passing through the earth’s centre ? Explain .
Ans. The centripetal force required for the orbital motion of the satellite is provided by the gravitational force of attraction. Gravitational force is a central force, i.e.., it passes through the centre of mass of the earth and the satellite. Hence, the plane of orbit of the satellite has to pass through the earth’s centre.