Exercise 3: sample answer

A typical result: in the first 30 seconds a large amount of water runs out, in the next 30 noticeably less, and by the end of a few minutes the stream is a trickle. This is because the pressure at the hole depends on the depth of water above it, so as the level drops the flow slows.

Example write-up: "The cup lost about a third of its water in the first half minute and only a small amount in the last. The flow was not steady, which shows why simple outflow water clocks needed marks that were spaced unevenly, or a tank kept at a constant level, to be reliable."

Extension: if you keep the cup topped up to the same level using a second container, the flow becomes much steadier, which is the idea behind the better ancient designs.