Extreme Science: Inertia Sticks

Duck Calls

What you will need:

  • Plastic drinking straw
  • Scissors
  • Adult supervision

Procedure:

1) Begin by cutting your drinking straw in half. I like to cut it so that one half is longer than the other half rather than cutting it right in the middle.

2) Take one of your cut straws and flatten the last inch or two by rubbing the handle of your scissors over the straw “flattening” it on the table as shown;

3) Cut flattened end of straw to a point as shown;

4) Lay straw flat on table and run scissor handle over flattened/cut end to “curl as shown. Turn straw over and repeat on other side so that the pointed end of the straw is curled as shown;

5) Place cut/pointed end of straw in your mouth making sure that the pointed end is well inside your lips. Blow on the straw to make what sounds like a duck call.

What is going on?

When you blow on the straw, the air rushing through the inside of the straw causes the two pointed flaps to repeatedly “slap” together causing a vibration which, in turn, produces sound. The air around us has 14.7 lbs PSI. Moving air has less pressure. By blowing through the straw, you are causing a low pressure area between the two points causing them to move together rapidly. When you rubbed the handle of your scissors over the end of the straw, you curled the pointed ends outward, which helps to now separate the ends once they have “slapped” together. This rapid vibration causes the straw to produce a “duck call” sound.

Try this:

Try different lengths of straws to see what effect the length may have on the tone produced. What happens if you do not curl the pointed ends? Are you still able to produce sound?

Radical Rick

Extreme Science

www.extremesciencefun.com