What you need:
- A dark-coloured balloon
- A small, bouncy ball
What to do:
1. Squeeze the ball into the mouth of the un-inflated balloon.
2. Blow air into the balloon but do not tie its mouth.
3. Holding the mouth of the balloon pinched, turn the balloon so that the ball falls to its mouth. Let go of the mouth.
4. Now, turn the balloon again so that its mouth is facing up.
What happens:
When the mouth of the balloon is facing down the ball falls to the neck and helps keep the balloon inflated. When the balloon is turned again, its mouth faces up. Still the ball stays in place, holding the balloon inflated.
It is only when you tap the side of the balloon gently to dislodge the ball the balloon deflates.
Why?
When you inflate a balloon, you push air molecules into the balloon and pack them in its elastic membrane. If you don’t knot off the balloon’s mouth, the elastic material of the balloon bounces back to its normal shape and pushes the air out.
However, when the bouncy ball plugs itself into the mouth of the balloon, it does not allow the air to whoosh out.
And the pressure or push of the air inside the balloon is higher than the surrounding air (since by blowing air in, you have packed in a lot of air in a small space).
This higher push keeps the ball in place at the mouth and the balloon stays inflated. This holds true even when the mouth of the balloon faces up.
Picture Credit : Google
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