Experiment with Wind in a Bottle

Scientists study the natural world by using the "scientific method." When a scientist observes some phenomenon in nature he develops an idea, called a theory or hypothesis, about what is happening. Then he does an experiment to test his hypothesis. If the results are as expected, then the experiment confirms the hypothesis which makes it more likely that the theory is correct. If the experiment fails and the results are not as expected, then the experiment has disproved the hypothesis and the scientist must come up with a new theory that he can test.

In ancient times great thinkers came up with intricate theories to explain nature, but did not always subject them to experiments. For example, the great Greek thinker Aristotle had a theory that heavy objects would fall faster than light objects. Aristotle was considered such an authority that this idea was accepted for centuries until the scientist Galileo performed an experiment by dropping two spheres of different weights off the leaning tower of Pisa. Galileo discovered they hit the ground at the same time and that Aristotle's theory had been wrong.

Here's an experiment that you can use to prove or disprove a common-sense theory:

STEP 1)Obtain an empty bottle with a small neck. A diameter of 1/2 inch should be ideal.

STEP 2)Cut a sheet of notebook paper to a square 5 inches on each side.

STEP 3)Crumple the paper into a tight wad.

STEP 4)Lay the bottle on its side and place the paper so it lays loosely in the neck of the bottle.

Construct a theory about what will happen if you put your mouth about a half inch from the neck of the bottle and blow a single hard towards it. A common sense theory might be that the wad would be blown into the bottle by the force of the breath. Now conduct your experiment to see what really happens.

If your theory was that the wad would be blown by the force of the air into the bottle, your experiment probably gave you unexpected results. In most cases the wad is blown out of the neck of the bottle in the opposite direction than expected. A new theory might be that wind rushing into the bottle creates a whirlwind of air currents in the closed space pushing the wad out. It is assisted by a rise in pressure inside the bottle as the air is compressed by the force of the breath.