Question 1 Why makes a balloon get inflated when air is filled in it?
Question 2 Why a bicycle tube get inflated when air is filled in it?
All the gases exert pressure on the walls of the container.
(1) Air is a mixture of gases.
(2) All the gases are made up of tiny particles called molecules which move around quickly in all directions.
(3) The fast moving gas molecules collide with one another and with the walls of the container.
Air pressure arises due to the constant collision of the tiny molecules of the gases present in air with the walls of the container it is enclosed.
(4) If a certain mass of air is compressed into a smaller volume then the number of collisions of air molecules per unit area increases and hence the pressure exerted by air goes up.
(5) If the container of air has stretchable walls then the higher pressure exerted by air inflates the container.
Take a rubber balloon and fill air into it with mouth or by pump. On filling in air, the balloon gets inflated i.e. expands and become bigger in size. When we put a lot of air in the balloon then the number of gas molecules in the balloon increases too much. The large number of gas molecules cause too many collisions with the walls of the balloon from inside and create a high pressure air pressure. This high pressure produced by the gas molecules on the walls of balloon causes it to expand and get inflated.
When air is pumped into a bicycle tube by using a pump, the bicycle tube gets inflated due to the air pressure exerted by the collisions of gas molecules in air with the inner walls of the rubber tube. This air pressure in the bicycle tube makes the bicycle tyre feel hard.