Yes, an air-filled balloon can float in the air under certain conditions. The ability of a balloon to float depends on the density of the gas inside the balloon compared to the density of the air surrounding it.
If the gas inside the balloon is less dense than the surrounding air, the balloon will experience buoyancy and float upward. This is because buoyancy is determined by the difference in density between the object (in this case, the balloon) and the fluid (air) it is immersed in.
When an air-filled balloon is released, the gas inside the balloon is typically less dense than the surrounding air. This is because the gas inside the balloon, such as helium or hydrogen, has a lower density compared to the air. The lower density gas creates an upward buoyant force that exceeds the weight of the balloon itself, causing it to float.
However, it's important to note that not all gases can make a balloon float. For example, regular air (composed mostly of nitrogen and oxygen) has a density similar to the surrounding air, so an air-filled balloon would not experience significant buoyancy and would not float. Special gases like helium or hydrogen, which are less dense than air, are typically used to inflate balloons to make them float.
It's worth mentioning that the safety and practicality of using certain gases, such as hydrogen, in balloons can vary. Helium is commonly used for party balloons and airships due to its non-flammable nature, while hydrogen, although highly buoyant, is highly flammable and presents safety risks.