Question

Explain briefly why a balloon filled with helium gas rises in air?

Answer 1

A balloon filled with the helium gas rises in the air due to following reasons:

1. The weight of helium gas is less than that of air outside the balloon.
2. The density of helium gas is less than that of air outside the balloon.
3. An upward force (buoyant force by air) acts on the balloon which keeps it rising in the air.
4. Once the balloon reaches the height where the density of the air is nearly equal to the gas inside the balloon the buoyant force by air stops acting in it and the balloon remains at the same height.