Air/Atmosphere exerts pressure on the Earth’s surface - A classroom experiment for 8th standardGood morning, sit-down all
Sir: Ravi, can you summarize what we have learned in the last class?
Ravi: Sure sir,
Air is a colorless, odorless and tasteless gaseous mixture surrounding the Earth and from the surface of the Earth, up to 800km above, a layer of air exists which is called the Atmosphere. Thus, on the Earth, we all are surrounded by the air from all the sides. The pressure applied by the atmosphere is called Atmospheric pressure or Air pressure and the pressure is the force that the atmosphere applies on the Earth's surface.
Sir: Very good
Today we are going to make a simple classroom activity to show that air/atmosphere exerts pressure on the Earth's surface.
Empty narrow mouth plastic-bottle, a needle/pin, and water
Take the narrow mouth plastic-bottle. Make a hole in its cap and a hole in the bottle. Fill water in the bottle up to the level below the hole and close the bottle with cap.
(1) Invert the water-filled bottle. You see water flowing out through the cap hole.
(2) Now you close or cover the hole on the bottle with your thumb/ finger. You can notice the water doesn't come out through the cap hole.
Why did water stop flowing out?
Because when you close the hole on the bottle with your thumb, atmospheric air couldn't enter into the bottle through this hole. Therefore, the atmospheric air applied pressure on the hole of the cap from outside. This outside air pressure restricted the inside bottle water to flow out through the hole of the cap.
So students, today through above activity, we proved that air applies pressure on the Earth's surface.
See you in the next class.