Special Science Teleclass: Sonic Vibrations

Monday September 15, 2014

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!


Sound is a form of energy, and is caused by something vibrating. So what is moving to make sound energy?


Molecules. Molecules are vibrating back and forth at fairly high rates of speed, creating waves. Energy moves from place to place by waves. Sound energy moves by longitudinal waves (the waves that are like a slinky). The molecules vibrate back and forth, crashing into the molecules next to them, causing them to vibrate, and so on and so forth. All sounds come from vibrations.


Materials:


  • 1 tongue-depressor size popsicle stick
  • Three 3″ x 1/4″ rubber bands
  • 2 index cards
  • 3 feet of string (or yarn)
  • scissors
  • tape or hot glue
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Resonance Exerices

Sunday November 29, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


Some of these questions you might recognize from the last lesson on potential energy, but we put them here again so you can see how they are inter-related. Have fun!


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Answers to Resonance Exercises

Sunday November 29, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.


Answers:
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Vibrations Exercises

Sunday November 29, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


Some of these questions you might recognize from the last lesson on potential energy, but we put them here again so you can see how they are inter-related. Have fun!


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Answers to Vibrations Exercises

Sunday November 29, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.


Answers:
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Air Horns & Sonic BOOM!

Sunday November 29, 2009

f18Sound can change according to the speed at which it travels. Another word for sound speed is pitch. When the sound speed slows, the pitch lowers. With clarinet reeds, it’s high. Guitar strings can do both, as they are adjustable. If you look carefully, you can actually see the low pitch strings vibrate back and forth, but the high pitch strings move so quickly it’s hard to see. But you can detect the effects of both with your ears.


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The Best Parent-Annoyer Ever

Sunday November 29, 2009

This is one of my absolute favorites, because it’s so unexpected and unusual… the setup looks quite harmless, but it makes a sound worse than scratching your nails on a chalkboard. If you can’t find the weird ingredient, just use water and you’ll get nearly the same result (it just takes more practice to get it right). Ready?


NOTE: DO NOT place these anywhere near your ear… keep them straight out in front of you.


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Seeing Sound Waves

Sunday November 29, 2009

This section is actually a collection of the experiments that build on each other.  We’ll be playing with sound waves, and the older students will continue on after this experiment to build speakers.


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Humming Balloon

Sunday November 29, 2009

You can easily make a humming (or screaming!) balloon by inserting a small hexnut into a balloon and inflating. You can also try pennies, washers, and anything else you have that is small and semi-round. We have scads of these things at birthday time, hiding small change in some and nuts in the others so the kids pop them to get their treasures. Some kids will figure out a way to test which balloons are which without popping… which is what we’re going to do right now.


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Good Old Telephone

Sunday November 29, 2009

telephoneThis is the experiment that all kids know about… if you haven’t done this one already, put it on your list of fun things to do. (See the tips & tricks at the bottom for further ideas!)


We’re going to break this into two steps – the first part of the experiment will show us why we need the cups and can’t just hook a string up to our ear.  Are you ready?


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Seeing Sound Waves using Light

Sunday November 29, 2009

After you’ve completed this experiment, you can try making your own sound-to-light transformer as shown below. Using the properties of sound waves, we’ll be able to actually see sound waves when we aim a flashlight at a drum head and pick up the waves on a nearby wall.


Here’s what you need:


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Thunder and Lightning

Sunday November 29, 2009

When there’s lightning, thunder is not far behind.  Even if you don’t live in a tropical thunderstorm area, you can still simulate this experiment using the variations below and get the most out of the main ideas about sound waves and light waves.


For starters, let’s assume you’re waiting for a good storm. When one’s brewing, grab a timer and a pencil with paper and wait inside the house near a window.


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What is Frequency?

Sunday November 29, 2009

In this experiment you will be adjusting the length of string of a pendulum until you get a pendulum that has a frequency of .5 Hz, 1 Hz and 2 Hz. Remember, a Hz is one vibration (or in this case swing) per second. So .5 Hz would be half a swing per second (swing one way but not back to the start). 1 Hz would be one full swing per second. Lastly, 2 Hz would be two swings per second. A swing is the same as a vibration so the pendulum must move away from where you dropped it and then swing back to where it began for it to be one full swing/vibration.


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Ear Tricks

Sunday November 29, 2009

Think of your ears as ‘sound antennas’.  There’s a reason you have TWO of these – and that’s what this experiment is all about.  You can use any noise maker (an electronic timer with a high pitched beep works very well), a partner, a blindfold (not necessary but more fun if you have one handy), and earplugs (or use your fingers to close the little flap over your ear – don’t stick your fingers IN your ears!).


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Chladni Plates

Sunday November 29, 2009

chladniThis experiment is just for advanced students. Ernst Florens Friedrich Chladni (1756-1827) is considered to be the ‘father of acoustics’. He was fascinated by vibrating things like plates and gases, and his experiments resulted in two new musical instruments to be developed.


When Chladni first did these vibrating plate experiments (as shown in the video below), he used glass plates instead of metal. He was also one of the first to figure out how to calculate the speed of sound through a gas.


And it will completely blow your mind. Chladni patterns are formed with a metal plate covered in regular table salt is vibrated through different frequencies.


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Transverse and Longitudinal Waves

Sunday November 29, 2009

Since we can’t see soundwaves as they move through the air, we’re going to simulate one with rope and a friend. This will let you see how a vibration can create a wave. You’ll need at least 10 feet of rope (if you have 25 or 50 feet it’s more fun), a piece of tape (colored if you have it), a slinky, and a partner. Are you ready?


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How a Record Player Works

Sunday November 29, 2009

Before CDs, there were these big black discs called records. Spinning between 33 and 45 times per minute on a turntable, people used to listened to music just like this for nearly a century. Edison, who had trouble hearing, used to bite down hard on the side of his wooden record player (called a phonograph) and “hear” the music as it vibrated his jaw.


Many people today still think that records still sound better than CDs (I think they do), especially if the record is well cared for and their players are tuned just right. Here’s a video on how a record works:


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Building Speakers

Sunday November 29, 2009

Alexander Graham Bell developed the telegraph, microphone, and telephone back in the late 1800s. We'll be talking about electromagnetism in a later unit, but we're going to cover a few basics here so you can understand how loudspeakers transform an electrical signal into sound.

This experiment is for advanced students.We'll be making different kinds of speakers using household materials (like plastic cups, foam plates, and business cards!), but before we begin, we need to make sure you really understand a few basic principles. Here's what you need to know to get started:

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Unit 6: Sound Waves (Resonance) Video

Sunday November 29, 2009

This lesson, I’d like to take the concepts of frequency and vibration just a bit further and talk about natural frequency and resonance. Are you ready?



Here’s the video for the Tacoma Narrows Bridge (this is the actual video shown to the public at the time):





Unit 6: Sound Waves (Vibrations) Video

Sunday November 29, 2009

Energy moves in waves. Before we get in over our heads talking about sound waves, though, we need to spend some time on this vibration thing. This lesson we will be taking a careful look at vibration and frequency.



Buzzing Hornets

Monday July 27, 2009

hornet1Sound is everywhere. It can travel through solids, liquids, and gases, but it does so at different speeds. It can rustle through trees at 770 MPH (miles per hour), echo through the ocean at 3,270 MPH, and resonate through solid rock at 8,600 MPH.


Sound is made by things vibrating back and forth, whether it’s a guitar string, drum head, or clarinet. The back and forth motion of an object (like the drum head) creates a sound wave in the air that looks a lot like a ripple in a pond after you throw a rock in. It radiates outward, vibrating it’s neighboring air molecules until they are moving around, too. This chain reaction keeps happening until it reaches your ears, where your “sound detectors” pick up the vibration and works with your brain to turn it into sound.


You can illustrate this principle using a guitar string – when you pluck the string, your ears pick up a sound. If you have extra rubber bands, wrap them around an open shoebox to make a shoebox guitar. You can also cut a hole in the lid (image left) and use wooden pencils to lift the rubber band off the surface of the shoebox.


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Harmonicas

Monday July 27, 2009

Your voice is a vibration, and you can feel it when you place a hand on your throat when you speak. As long as there are molecules around, sound will be traveling though them by smacking into each other.


That’s why if you put an alarm clock inside a glass jar and remove the air, there’s no sound from the clock. There’s nothing to transfer the vibrational energy to – nothing to smack into to transfer the sound. It’s like trying to grab hold of fog – there’s nothing to hold on to.


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BONUS! Nine Sonic Vibes Experiments to Mystify Your Kids

Tuesday June 30, 2009

Kazoo

Cut a piece of tissue paper the same length as a plastic comb (make sure the comb’s teeth are close together). Fold the tissue paper in half, wrapping it around the teeth of the comb.  Place it lightly between your lips and hummm… you’ll feel an odd vibrational effect on your lips as your kazoo makes a sound! You can try different papers, including waxed paper, parchment, tracing paper, and more!


Poppers

Cut the neck off a small balloon (balloons made for water bombs work well) and stretch it over the opening of a film canister. Pinch the drum head and pull up before you release – POP! You can change the pitch by adjusting the stretch of the drum head.
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