Define gravitational field strength in words.
A lone star has radius $R$. The star’s mass can be treated as though it were a point mass at the star’s centre. The gravitational field strength at the star’s surface is $g_s$. On Fig. 1.1, sketch a graph that shows how the star’s gravitational field strength varies with distance from its centre. Use the distance range from $R$ to $4R$.
The Earth and Moon can be treated as spheres isolated in space, with their masses concentrated at their centres. The masses of the Earth and Moon are $6.00 \times 10^{24}\,\text{kg}$ and $7.40 \times 10^{22}\,\text{kg}$ respectively. The radius of the Earth is $R_E$ and the separation between the centres of the Earth and the Moon is $60R_E$, as shown in Fig. 1.2.
Explain why a point exists between the Earth and the Moon where the gravitational field strength is zero.
Find the distance, in terms of $R_E$, from the Earth’s centre at which the gravitational field strength is zero.
On the axes in Fig. 1.3, sketch a graph to show how the gravitational field strength varies with position between the surface of the Earth and the surface of the Moon.