Why does a ship float in water while a needle sink in water?
A ship can float not because of density, but because of the amount of water it "pushes" aside to make the ship feel like a normal styrofoam. It displaces the water to some other further areas. It’s also caused by air in the ship, causing a reaction between earth’s gravity and the force of the water, pushing the boat upwards. Mainly it is also of the shape of the entire ship. It is designed to be like that. Same goes for swimming.
To understand what makes a heavy steel ship float, you have to think of “floating” as the point at which an object stops “sinking”. An object floats on water because it displaces – or takes the place of – the amount of water equal to it’s own weight. The more water the ship displaces the more “boyant”, or floatable, it becomes. A ship (or anything else that floats) sinks into the water until it has displaced its own weight of water, then it will not sink any further. If a ship weighing 100 tons is placed in the water, it will move aside up to, but no more than 100 tons of water. Because a ship is a lot like an empty bowl – relatively thin steel on the outside and nothing but air on the inside – its actual density is less than that of the water it displaces. So, a 100 ton ship will not displace so much water that it goes down into the water below the sides of the boat. This causes the ship to float on the water. This explains why a solid block of steel will sink and a hollow bowl of ste