Does the air exert buoyant force on all objects in air or only on objects such as balloons that are very light for their size?
All liquids and gases in the presence of gravity exert an upward force called buoyancy on any object immersed in them.If the object is less dense than the liquid or gas, buoyancy will make it float and The apparent weight of an object is decreased by the weight of the fluid object displaces.The density of air is very small and it is difficult to notice unless the density of object is too small object.The apparent weight is decreased due to the buoyant force of the air it is displacing. If the displaced air weighs more than the objec displacing it, the object floats in the air. If not, then it settles to the ground. Most things are a lot more dense than air so we don't notice the buoyant forces because they are trivial compared to the force of gravity on the object but they are present. When you get into a much denser fluid like water, the buoyant forces we can easily notice.