Here's how it works:

* Buoyancy is an upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object.

* Archimedes' Principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object.

* If the buoyant force is greater than the weight of the object, it will float.

* If the buoyant force is less than the weight of the object, it will sink.

Examples:

* A boat floats because the buoyant force of the water is greater than the weight of the boat.

* A hot air balloon rises because the hot air inside the balloon is less dense than the surrounding air, creating a buoyant force that lifts the balloon.

Let me know if you'd like more details on any of these concepts!