The same steel, the density will not change, and the same place (generally on the earth) will not change; When steel is made into a ship, the displaced liquid volume is greater than its own gravity, that is, F (floating) >; G (gravity), the ship will float.
Therefore, the steel with the same quality can float when it is unfolded into a boat shape and the displacement increases; If you knead it into a ball, it will sink.
Modern ships are made of steel, which is more than 7 times heavier than water; The goods carried on board, such as grain, machinery and construction equipment, are also much heavier than water. Why can such a heavy thing float on the water?
To illustrate this problem, we can do an experiment: put a thin iron sheet in water and it will sink immediately; If this iron sheet is made into a box, its weight will not change, but it can float on the water; Not only that, if you put something in the box, the box will only sink a little and still float on the water. This is because the bottom of the box is subjected to water pressure, that is, vertical buoyancy. As long as the buoyancy is greater than the weight of the iron sheet, it will hold the iron box so that it will not sink.
Of course, both sides of the iron box are also under water pressure, but the pressure on the front and back sides is equal in size and opposite in direction, which cancels each other out; The pressures on the left and right sides also cancel each other out. Buoyancy increases with the depth of water and the volume of the submerged part of the object. Because the iron box is much larger than the iron sheet, the weight of boiling water is much larger, and the buoyancy generated is much greater, so the things in the box can still float on the water. The reason why big ships can float on the water is the same. The law of ups and downs of objects was discovered by the Greek scholar Archimedes more than 2000 years ago. He accurately said: "The buoyancy acting on an object in water is equal to the weight of boiling water discharged by the object." The bigger the ship, the deeper the draft, which means that the greater the weight of boiling water discharged by the ship, the greater the buoyancy the ship gets, and of course it can hold more things.