A nail sinks in water because its density is greater than the density of water.
Understanding Density and Buoyancy
To understand why a nail sinks, we need to consider the concepts of density and buoyancy.
Density
Density is a measure of how much mass is packed into a given volume. It's calculated by dividing an object's mass by its volume:
Density = Mass / Volume- Iron Density: The density of iron, the material nails are typically made of, is approximately 7.87 g/cm³.
- Water Density: The density of water is approximately 1 g/cm³.
Since iron is much denser than water, a nail has more mass packed into the same volume compared to water.
Buoyancy and Upthrust
Buoyancy is an upward force exerted by a fluid (like water) on an object immersed in it. This force is also called upthrust. The magnitude of this force is equal to the weight of the fluid displaced by the object.
- Archimedes' Principle: This principle states that the buoyant force on an object is equal to the weight of the fluid that the object displaces.
Why the Nail Sinks
Here's the breakdown of why a nail sinks, as per the provided reference:
- Weight vs. Upthrust: The nail's weight, which is a consequence of its high density, is greater than the upthrust (buoyant force) exerted by the water.
- Net Force: Because the weight of the nail is greater than the upthrust, the net force on the nail is downwards, causing it to sink.
| Property | Nail (Iron) | Water |
|---|---|---|
| Density | High (~7.87 g/cm³) | Low (~1 g/cm³) |
| Upthrust | Low | N/A |
| Weight | High | N/A |
| Result | Sinks | N/A |
Example
A small piece of wood will float because its density is less than that of water and the upthrust force is large enough to balance its weight. But the nail made of iron sinks due to its high density and comparatively less upthrust because it displaces small amount of water.
In Summary
The density of iron is significantly greater than that of water. As a result, the weight of the nail exceeds the upward buoyant force, causing the nail to sink. This is clearly described in the reference, where it states "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".
