Air pressure is an invisible force all around us . We live under a blanket of air and all that air exerts a substantial force on all living things. That pressure is the reason that our bodies appear the way they do, why seas and oceans experience storms and cyclones etc. So let us utilise the pressure from air to create a fountain in a bottle and spray it at your friends for fun ! Let’s learn how the forces of air and water combine to make a fun sprinkly toy.
What you need: a 100 ml plastic bottle , a straw ( bendy straw preferably ) , a balloon , 75 ml water , a pen / compass, thread (optional)
How to do it:
- Use a compass/ pen to poke a hole at the base of the bottle’s neck.make the hole large enough to just fit the straw not any bigger .
- Pass the straw through the hole making sure there are no gaps in between the hole and straw.
- The straw should not be bent and its one end should be touching the base of the bottle.
- Fill the bottle with water just upto the level of hole .
- Inflate your balloon and pinch it with your fingers to hold the air in . You can also tie a thread around it .
- Without letting go of the air , stretch the balloon’s opening over the mouth of the bottle .
- Now let go of the pinched end of the balloon or remove the thread to allow the air to pass through .A fountain of water spurts out the straw !
Note : If there are gaps between the straw and hole the water will not spray out as the air easily escapes. Seal the gaps if any with dough or clay.
What really happened there:
Air exerts pressure in a closed as well as open space .Here the air is trapped in the balloon and thus exerts pressure on the balloon wall.
Also the air outside the balloon exerts pressure on it – this is called atmospheric pressure.
When you let go of the balloon the air rushes from a closed space ( the balloon) into an open one ( the bottle) . We know that gases like us take up space thus as the air moves into the bottle it takes up space but the bottle has a limited volume .
To make space for itself, the air pushes the water out of its way .The water is being forced out of the bottle and its only escape is through the straw with its small opening . Due to these 2 factors :
- High air pressure from the balloon and
- Small sized opening of the straw
The water doesn’t just come out gently but gushes out in the form of a fountain.
Thus air pressure can be a fun tool to use to make gadgets, toys and experiment with . Go exploring and look for objects in your house that use air pressure to work or generate air pressure as they work themselves.
Can you create air pressure yourself ? Share all your learnings and findings with us !