Bernoulli Balloon


Objective

Have you ever wondered if there is a faster way to blow up a balloon?

Supplies

  • Long plastic bag with one end sealed

Procedures

  1. Hold the bag to your face and see how long it takes to completely fill the bag with air.
  2. Hold the open end of the bag away from your face and blow into the opening.

Watch out!

Students with any kind of respiratory problem (bronchitis, asthma, etc.) should take extra care and precautions when blowing up the bags.

Plastic bags pose a suffocation hazard, especially when working with small children. Bags are not toys, and this experiment should only be performed with young children with adult supervision.

Take-away

You’re able to blow up the bag more quickly when holding it away from your face than by breathing directly into it, as if you were blowing up a balloon, because of the Bernoulli effect. When you hold the bag to your face, only the air from your lungs can fill the bag. When you hold the bag away from your face, fast moving air from your lungs goes into the bag and creates an area of low pressure around it. Higher pressure air then rushes to fill the area of low pressure, getting sucked into the bag along with the air from your lungs!

For more information, please visit Steve Spangler Science.