At first displacement appears to be far from fascinating. Simply put, the volume of an object, when submerged in water, pushes aside the same volume of water. This simple process allows anyone to measure the precise volume of any object by then measuring the amount of fluid that either spills out of the top of the container or rises by said amount in a measuring cylinder.
It become a little more interesting when you consider that it’s this effect that enables enormous supertankers weighing up to 400,000 tons to float. For example, when a supertanker is launched into the sea it will sink if the water it displaces is equal to or exceeds the weight of the ship itself. However, if when launched its weight is less than that of the water it displaces and its shape allows it to displace the weight faster than the water will reach the tanker’s submerging point, no matter how large or full of cargo, then it will float.
Of course, if you were to drop a solid iron bar into a swimming pool, it would sink straight away because: firstly, its weight far outweighed that of the water it was displacing and secondly, even if its weight was less than that of the water, its shape would not allow it to displace the weight fast enough. This is why ships’ hulls are shaped how they are.
So while the scientific principle might lack WOW factor, it does enable fantastic feats of engineering like the TI class supertankers, the largest ocean going-ships in the world. They’re an incredible 379 meters long, 68 meters wise and have a deadweight of some 441,585 metric tons and float thanks to the law of displacement discovered by Archimedes in the Original Eureka moment.