(a)[1]
Define what is meant by gravitational field strength.
(b)[2]
Explain why, for small changes in vertical position of a point mass near the Earth’s surface, the gravitational field strength can be treated as constant.
(c)[5]
Earth’s orbit around the Sun is approximately circular, with a radius of $1.5 \times 10^{8}\,\text{km}$. The orbital period is $365$ days. Determine a value for the mass $M$ of the Sun. Explain your working.