Blow 'em apart! sience experiment : Fizzics Education

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Blow ’em apart!

Blow ’em apart!

Follow FizzicsEd 150 Science Experiments:

You will need:

  • Two balloons
  • Two 20cm length strings
  • One rod or stick
  • Two equally-high stacks of books

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Blow em apart science experiment - materials needed
1 Blow em apart science experiment - materials needed

Stack 2 pillars of books, and place the rod across the two stacks.

2 Blow em apart science experiment - string tied to a red balloon

Blow the balloons up, tie the balloon ends and attach 1 string to each balloon.

3 Blow em apart science experiment - balloons hanging down and ready to go

Tie the strings to the rod, so that the balloons hang freely from the rod.

4 Blow em apart science experiment - student blowing apart balloons during a Fizzics video conference

Make sure the balloons are the same height.

5 Blow em apart science experiment - blowing between the two hanging balloons

Blow between the balloons, can you blow them apart? Try using a hairdryer!

“Can you blow these balloons apart?”

Why can’t you do it?

6 A student holding a paint roller with toilet paper flying off it due to a leaf blower.

Why Does This Happen

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 air moved between the balloons, creating a low-pressure zone between the balloons. The high pressure surrounding the balloons pushed the balloons together.

Low air pressure occurs when air is sped up. The energy of the air molecules is being used mostly to move them faster, and less to bounce them off of each other and the balloons. Without as many collisions between the air molecules, the pressure between them is lower, and surrounding, slower-moving air molecules have more energy to bounce into the space, moving the balloons towards each other as they move in. The way that moving gases and fluids work is that slower air will move towards faster air.

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.

Variables to test

More on variables here

  • Does it matter about the size of the balloons?
  • Try blowing between two helium balloons
  • What if the balloons are filled with water?

Learn more!

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