(a) What is the gravitational potential energy per unit mass at a point located at 2re from the centre of the Earth, where re is the radius of planet Earth? (You may ignore any effects from other planets and the Sun).
(b) Without calculating any velocity, find the minimum kinetic energy required for a 28,000 kg rocket to escape the Earth. (If velocity is used you will receive no marks. You may ignore any drag or friction).
(c) To what size (in km) would the Sun's radius have to be reduced for its escape speed to be equal to half the speed of light? (Only the new radius is needed not the change in the radius).
(d) By considering radial gravitational fields, briefly describe the relationship between the stable orbit of a satellite around the Earth and the equipotentials of the Earth's gravitational field.