(a(i))[1]
A gravitational field can be shown by lines of gravitational force. State what is meant by a line of gravitational force.
(a(ii))[3]
By referring to the lines of gravitational force near the Earth’s surface, explain why the gravitational field strength $g$ close to the Earth’s surface is approximately constant.
(b)[4]
The Moon may be treated as a uniform sphere of diameter $3.4 \times 10^{3}\,\text{km}$ and mass $7.4 \times 10^{22}\,\text{kg}$. The Moon has no atmosphere. In a collision between the Moon and a meteorite, a rock is projected vertically upward from the Moon’s surface at a speed of $2.8\,\text{km s}^{-1}$. Assuming that the Moon is isolated in space, determine whether the rock will travel out into distant space or return to the Moon’s surface.