Question

A steel needle sinks in water but a steel ship floats. Explain how

Answer 1

An object will float in water if its density is less than that of water. A steel needle sinks since its density is more than water. The interior of a ship is hollow. Therefore, its average density is less than that of water, therefore, it floats.

Answer 2

According to Archimedes law the upward boyuant force that is exerted on a body immersed in a fluid , whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid. An iron nail sinks because it has more weight than the weight of the water it displaces.