1.1. The distance between the Sun and Mercury varies from 4.60 × 10¹⁰ m to 6.98 × 10¹⁰ m.  The gravitational attraction between the Sun and Mercury is F when they are closest together. 

Write an expression for the gravitational attraction, in terms of F, when they are furthest apart.

1.2. Mercury has a mass of 3.30 × 10²³ kg and a mean diameter of 4880 km.  A rock is thrown vertically upwards from its surface with a velocity of 10 m s^–1.  

Calculate how long it will take for the rock to return to the surface of Mercury.

1.3. Venus is approximately 5.00× 10¹⁰ m from Mercury and has a mass of 4.87× 10²⁴ kg.  A satellite of mass 1.05× 10⁴ kg is momentarily at point P, which is1.34 × 10¹⁰ m from Mercury.

The angle between the satellite, Mercury and the Venus is 90^o, as shown in Figure 1.

Figure 1

Calculate the magnitude of the resultant force experienced by the satellite when it is at point P.