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“Yesterday is history. Tomorrow is a mystery. Today is a gift. That’s why we call it ‘The Present’.” – Eleanor Roosevelt

The Atmosphere


 

What is the Atmosphere?

The very thick layer of air which surrounds the Earth is called the atmosphere.

 

How thick is the atmosphere?

It is many miles thick. But beyond that, hundreds of kilometers up in space, there is no air at all.

 

Why do climbers usually take oxygen with them when they climb high mountains?

At ground level there is plenty of air. As we climb higher and higher, there is less and less air. That is why climbers usually take oxygen with them when they climb high mountains.

 

What are the importances of the atmosphere?

 

  • It protects us from the Sun’s dangerous rays (waves), such as UV rays (ultraviolet rays).
  • It gives us oxygen whenever we breathe.

 

Compressed Air

 

What is compressed air?

Air that has been squeezed a lot is called compressed air.

E.g. –  1) When you blow up a balloon, you are squeezing air into a small space.

          2) A tyre can be inflated (get filled with air). As you go on pumping more air into it the air gets squeezed or              compressed.

 

Compressed air is very strong. It can hold the weight of a cycle, a car or any other vehicle and we don’t feel the bumps in the road. Compressed air also makes things fall slowly.

E.g. – Parachute

 

According to the above examples we can learn that the air occupies space and it has a weight. Air also has pressure.

 

What are the uses of compressed air?

 

  • To fill balloons with air.
  • To fill tyres with air.
  •  Used in dentist’s drills and pumps in hospital machines.
  • Used by robots in factories that make cars, and some other tools.

 

Things that need air pressure

 

  • Straws
  • Medicine droppers
  • A doctor’s syringe
  • Tube wells