Pneumatics: wonder why the card doesn't fall off even with the water in the glass? click to find out why!

Hello steemians! It's Hive account@faithfulomoy and in this video, I'm going to show you an amazing trick/experiment to prove air actually flows in all directions. This experiment is a very simple one which you can do at home right now! It requires just three (3) apparatuses; a glass, water and a paper card. So, go get them and let's get started!

Procedure

• Pour water into the glass almost to the brim

• Put the card over the mouth of the glass

• Place one of your palms on the card and apply little pressure at the rim of the glass

• While your hand is still on the card, lift the glass with your other hand and invert the glass

• Now slowly take the hand holding the card away.

  Wow! The card doesn't fall off!

Working Principle behind this

Air exerts pressure in all directions and any subject in air is subject to the pressure from air molecules colliding with it.

For an area of 1m square, air exerts a force or weight equivalent to that which 140 men weighing 75kg will exert.

This air pressure is pushing up on the card from below while the water is pushing down on the card from above.

Diagram showing the forces on the water. The blue arrow indicates the forces due to air pressure below the card (water) and the red arrow indicates the force of gravity.

The force, as a result of the pressure from air, below and that from the water (force of gravity) above counterbalances to keep the paper card in place. By this means, the paper stays in place!!

Interesting right??

Thanks for watching and reading.

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