Question

Why do steel boats doesn't sink in water whereas the steel needle sinks?

Answer 1

density of the body. Density of a body is the mass divided by the volume of the body. Density of pin is more than water so it sinks. The density of an iron ship is mass of the ship divided by the volume of the ship. Although the ship is made of iron, the volume of the ship is so huge that density becomes less than the density of water. The reason being, the ship is not a mass of solid iron. There is lots of empty spaces and other less dense substances within the volume of the ship.