Answer:
Reasons are: Upward Bouyancy and Lower Average Density
Explanation:
Buoyancy force which simply means that, for an object to float on water, the density of the object must be lesser than the density of the water, otherwise it sinks.
In other words, this means that, if the density of an object is higher compared to the density of a water, the object sinks, but if the density of an object is lower compared to the density of water, the object floats.
The ship floats on water because, its density is lower than that of water.
The ship is constructed in such a way that, it has a trapped air or hollow space which help to reduce its average density compared to density of water, thus, it helps the ship to displace density of water that equals the density of the ship. Hence, the ships floats.
However, for the needle to float, it needs to displace its equal amount of density in water. But since the volume of needle is not enough to displace the density of water that can support it to floats, hence, it sinks.
