100 Days Project

Nanogirl: Star Science

Nanogirl wants to find 100 friends to do science experiments with her to prove that no matter who you are or what your education level, you can always have fun with science.

Day 35:

Daniel discovers Bernoulli's balloon principle

Daniel and I wanted to see if we could make a normal balloon float in the air like a helium balloon does.

First we started by blowing up a balloon and tying a knot to seal in the air.  Then we held the balloon out at arms length and let go, watching it drop to the floor.  This taught us that the balloon was more dense than the surrounding air (unlike a helium filled balloon).

Then we did the same thing but held a blowing hair dryer underneath the balloon which made the balloon rise and when we aimed the hair dryer at a certain angle, the balloon seemed to stay still in the air, not floating up or sinking down, just staying still.

The reason why the balloon stayed still in the moving stream of air from the hair dryer is due to a scientific concept called Bernoulli's Principle.

Bernoulli's Principle says that the pressure decreases inside a stream of flowing air so when the balloon tries to move out of this low pressure stream, the higher pressure of the air from inside the room pushes it back into the moving stream created by the hair dryer.  This pushing from the outside air and almost pulling from the hair dryer air stream means that the balloon essentially stays in the same position.

If you tilt the hair dryer too much then eventually the force of gravity will be greater than the force of the air pressure holding the balloon in the stream, and the balloon will fall to the ground.