This Instructable is for the everyday non scientist that is interested in learning a little bit about the science of music, and Zipper Music! What seems to be an immature person being annoying with their sweatshirt is actually a large amount of science! But let’s just shorten it down to what we can understand.
Step 1: Why Do Zippers Make Noise?
This question is essential to zipper music. Understanding this will help us manipulate the sound later on. Ok, so go look at a zipper. See the individual teeth? So as you pull, you can feel vibration and hear sound right? This is the friction of the two teeth coming together changing energy type from mechanical, the force you are putting on the zipper pull, to heat and sound as well as mechanical, the teeth coming together. This is because of the law of conservation of energy: energy cannot be created nor destroyed. It can only change form. Also Carnot's theorem says that you can't get 100% efficiency, you lose some energy to the other types present in this process. In our case, heat and sound. Friction between the metal parts creates heat, and vibration which in other words is sound. And this is why we hear the zipper.
Step 2: The Sound and How It Works.
So as we previously discussed, the sound is created by the friction. Now let’s dig a little deeper into the sound. Sound is made of sound waves moving. The rate at which they move in one set amount of time (a period) is called frequency and is measured in Cycles per Second, or more commonly known as Hertz, but in our case, we can look at it in teeth per second. Frequency in simple terms, is how high/low the sound will be. So the more sets of teeth in one second, the higher the sound. But the limitation of the “zipperstrument” is the fact that the higher the frequency, the shorter the length of the note can be. There is an equation for that, but it is complicated and we won’t touch it in this Instructable. (For more on the physics of sound, go to www.physicsclassroom.com).
Step 3: Controlling the Sound
So basically, the faster you move the zipper up and down, the higher it sounds, and the slower, the lower it sounds. This part is still experimental, but has potential. Different materials of zippers (metal vs. plastic) cause it to sound different. Even lengths of the zipper would change the sound because of the amount of material the vibrations have to pass through. To make successful zipper music, you really have to mess around. (Always remember that the longer you want the high notes, the longer the zipper will have to be.) That's the fun part! No two tunes will sound the same! Have fun! Please comment with any questions, and vote! I would really like to win Amazon's Zip It Good contest, so if you have any suggestions, let me know!