Physics

Problem

A communication satellite must appear stationary with respect to an observer on Earth’s surface. The period of such a satellite is

24\,\text{h}

. Using

G=6.67\times10^{-11}\,\text{N m}^{2}\!\text{/kg}^{2}

and

M_{\!E}=5.97\times10^{24}\,\text{kg}

, the required orbital radius (measured from Earth’s centre) is approximately a)

3.6\times10^{7}\,\text{m}

4.2\times10^{7}\,\text{m}

2.4\times10^{7}\,\text{m}

8.6\times10^{7}\,\text{m}