i havent done hsc physics for a while, but i have a feeling that theyd be looking for something along the lines of this:
okay a low earth orbit has a lower r, typically a few hundred km - a geostationary orbit has an orbit of about 35000km (if i remember correctly)
they might like to see some equations in here - for example v = sqrt(GM/r) where M is the earth's mass, and r is the distance from the centre of the earth. so then you can say that the low earth has a much higher velocity, since r is smaller.
the period of the low orbit is lower, period of geostationary is 24 hours
then you could talk about the different uses - geostationary is best for GPS and communication satellites, low earth might be used for spying or checking weather conditions
if you've still got room, you might want to chuck in orbital decay - hardly affects the geostationary because it is so high up the atmosphere is very thin.
hope this helps
