Question

Why does a ship made of iron float while a piece of iron sinks?

Answer 1

1. The density of iron is more than the density of water therefore the weight of the nail is more than the upthrust experienced by it causing it to sink.
2. However, a ship although much larger than the nail floats because the ship is hollow from the inside and this space is filled with air which reduces the average density of the ship lower than that of water.
3. Thus even with a small portion of the ship submerged under water, the weight of the water displaced by it becomes equal to the weight of the entire ship.
4. Therefore, a ship floats on water, and an iron nail sinks.