Here's why:
* Archimedes' Principle: This principle states that the buoyant force on an object submerged in a fluid (like air) is equal to the weight of the fluid displaced by the object.
* Density: The key is the density of the object compared to the density of the fluid. If the object is less dense than the fluid, it will experience an upward buoyant force greater than its weight, causing it to float (like a balloon).
* All objects experience buoyant force: Even heavy objects like a car or a house experience buoyant force from the air. However, the buoyant force is very small compared to the weight of these objects, so it's not noticeable.
Example:
Think about a rock. It's much denser than air. The buoyant force on the rock is small compared to its weight, so it sinks. But it does experience some upward force from the air!
In summary:
* All objects experience buoyant force from air.
* The magnitude of the buoyant force depends on the object's density and the density of the air.
* If the buoyant force is greater than the object's weight, the object floats.
