(a)[1]
State which planet is labelled X.
(b)[1]
Describe the link shown in Table 9.1 between a planet’s mass and the gravitational field strength at its surface.
(c)[1]
Explain why ‘distance from Sun’ in Table 9.1 is given as an average value.
(d)[3]
Demonstrate that the Earth’s average orbital speed is about $30\,\text{km s}^{-1}$.