Archimedes is asked to design a massive ship of a kind that has never been built before. And surely what he has to ask himself is, will it float? Will such a massive ship with so much on it actually be able to stay afloat? He knows that you can put all kinds of things in water and they will float. But why is it that some things float and other things don't? So a lump of gold will sink, but something of the same weight that is created as a kind of shallow vessel may well float. Why is that? The answer is what is still called the archimedes principle. That it about the force that acts from the water on the object