The first is a kind of warm-up question, dealing with general buoyancy principles. The other two are puzzlers, meant to exercise your mind. Don't fret if you find these too challenging ...

The most famous of these were the Archimedes' Screw (a device for raising water that is still used in crop irrigation and sewage treatment plants today) and Archimedes' principle of buoyancy.

Buoyancy is derived from carriers being less ... requiring more and more force to continue doing so. This principle means the ...