Why does this work?
The mathematician Bernoulli found that moving air has less pressure than air that is still.
In your experiment a low pressure area was created between the balloons when you tried to blow them apart. The faster the air moved between the balloons, the lower the air pressure in that space.
The high pressure surrounding the balloons pushed the balloons together.
The curved surface of the balloon also makes the air travel faster, causing even lower pressure as the air rushes around the edge of the balloon. Curved surfaces are used to create low pressure areas on plane wings and even F1 race cars! Another simple demonstration of this can be done with a funnel and ping pong balls or making vortex smoke rings
. Also, check out this engineering article on F1 aerofoil design
Other air pressure based science experiments
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