BUOYANCY IN AIR

Does buoyancy exist in air? => Yes, it does.

Object immersed in gas also experiences a buoyant force equal to the weight of the gas displaced.

Air is composed of different gases, mainly: = nitrogen = oxygen = carbon

Some gases like helium: => have lower densities like airThus, balloons with helium gas float.

HOT AIR BALLOONS

In hot air balloons, hot air is forced inside the balloon.

As air is heated, air expands and the density decreases.

The balloon goes up.As air in the balloon cools, it contracts,

letting outside cool air to enter.The density increases.The balloon now goes down.

During World Wars I and II, hot air balloons were used for:

=> transport => warfare => surveying => communicationToday, hot air balloons are used for: => leisure => gathering data in the atmosphere