(a(i))[1]
State what a line of force means in a gravitational field.
(a(ii))[3]
Using the pattern of the lines of gravitational force near the Earth’s surface, explain why the acceleration of free fall close to the Earth’s surface is approximately constant.
(b)
The Moon may be regarded as a uniform sphere isolated in space. Its radius is $1.74 \times 10^{3}\ \text{km}$ and its mass is $7.35 \times 10^{22}\ \text{kg}$.
(b(i))[2]
Calculate the gravitational field strength on the Moon’s surface.
(b(ii))[3]
A satellite is in a circular orbit about the Moon at a height of $320\ \text{km}$ above its surface. Calculate the time taken for the satellite to complete one orbit of the Moon.