Here is a hard one it is from one of my professors while I was in school:
Give a rough order-of-magnitude estimate of how acceleration might affect the rate of a clock through modification of the energy-level structure of the atom. Express your results, for example, in the acceleration (g), the size or the atom (l). How many earth gravitation acceleration must be imposed before there is a sizable change in the rate of modern atomic clocks?
Then because he was a dick he tells us this: You should be able to find relevant parameters for atomic clocks from sources like google, Wiki, ect.
Have fun! I will put up the solution later if you guys surrender.