A satellite is moving in a stable circular orbit around the Earth.
(i) State the condition that relates the gravitational force and the centripetal force acting on the satellite.
(ii) Using the condition stated in (i), write an expression for the orbital speed v in terms of the universal gravitational constant G, the mass of the Earth ME and the orbital radius r. Hence explain qualitatively how the orbital speed changes when the orbital radius is increased.
(iii) Without detailed calculation, determine by what factor the orbital period changes if the orbital radius becomes four times its original value. Give reasons for your answer.