Question

A piece of iron sinks in water but large ships made of iron float on water. Explain why?

Answer 1

Floatation and sinking of an object

1. A body must adhere to Archimedes principle in order to float.
2. The Archimedes principle is used to explain the law of flotation or the upward thrust felt when immersed in a fluid.
3. According to Archimedes, the upward buoyant force exerted on a body immersed in a fluid, whether partially or completely submerged, is equal to the weight of the fluid displaced by the body and acts in the upward direction at the center of mass of the displaced fluid.
4. The flotation and sinking of an object are dependent upon the relative density of each other.
5. If the density of an object is greater than the density of water, the object will sink.
6. If the density of an object is less than the density of water, it will float.
7. Because the density of iron is greater than the density of water, the weight of the nail exceeds the upthrust experienced by it, causing it to sink.
8. However, a ship, despite being much larger than a nail, floats because the ship is hollow on the inside and this space is filled with air, lowering the ship's average density below that of water.
9. Thus, even if only a small portion of the ship is submerged, the weight of the water displaced by it equals the weight of the entire ship.