Link to Whistle Stick, part 1

I hope that you made your own Whistle Stick, and have been playing...., I mean experimenting with it. I also hope that you spent some time thinking about the science behind the sound that it makes, because that is what we are going to explore this time. For your exploration, you will need:

- a wooden spoon
- a large container of water
- the Whistle Stick from last week

It's always good to start with the basics, so begin by thinking about sounds in general. We hear a sound because of waves traveling through the air. Just as dropping a stone into a pond causes waves to spread out across the water, popping a balloon, vibrating a guitar string, or singing a song causes waves to spread through the air. When those waves hit our ear drums, we hear the sound. That means that the Whistle Stick must be producing waves in the air. But how? That is where the wooden spoon comes in. We will use it in place of the popsicle stick, and look at waves in water instead of air. Hold the wooden spoon between your palms, with the end of the spoon in a container of water.
Slide your palms to twirl the spoon slowly in the water. As the spoon spins, it makes waves in the water. Try spinning it at different speeds, noticing how that changes the distance between the waves. What you should notice is that as the spoon twirls, it pushes on the water to send out a wave. As you spin the spoon faster and faster, it makes more waves, and those waves get closer and closer together.
Now lets think about sound waves. The picture at the right shows a graph of the sound produced by the whistle stick. Notice that at the start of the sound, it reaches far up graph. The higher up the graph it goes, the closer together the sound waves are, and the higher the pitch of the sound. If you click the picture, you can watch a short video, letting you hear the sound, seeing how the changing sound matches the graph.
It is much easier to see (and hear) if we slow things down. This graph shows the same sound, stretched out four times longer than the original. That lets us see the curve as the pitch falls. Again, you can click the picture to watch a short video. Because it plays the sound slower, it is easier to see (and hear) that the sound begins with a high pitch (waves very close together), and then the pitch falls as the waves get farther apart.

Now lets put that all together. Like the wooden spoon, the faster the popsicle stick spins, the closer together the waves will be, and the higher the pitch of its sound. When you first snap your fingers, the Whistle Stick spins very fast, making a high pitched sound. As it pushes against the air to produce those waves, it gives up some of its energy of motion. That causes it to spin slower, producing a lower pitched sound. Looking at the graph, we can see that the rate of spin slows very quickly at first, and then more gradually.

If you remember from last week, I also made a Whistle Stick from a tongue depressor that was much wider. it made a much lower pitched sound, that did not last nearly as long. Why? The wider blade had to push against more air, transferring the energy of motion much faster, causing the speed of its spinning to drop much faster.

If you want to do some experimenting, you might try cutting notches into the sides of the stick or doing other things to change its shape. Do you think that would change the sound? Sounds like a good reason to eat more popsicles to me.

This week's experiment is a trick that my Grandfather taught me when I was very young. He called it a "whistle stick", and making one brought back delightful memories from my childhood. This experiment requires the use of a sharp knife, so if you are young, you may need adult assistance. It is not difficult, but even adults should keep safety in mind. To try this you will need:

- a popsicle stick (with the popsicle removed) - a sharp knife with a short blade - a pencil or pen Making a Whistle Stick requires some whittling, the art of using a knife to shave thin slivers from a piece of wood. During my Grandfather's time, whittling was a common pass time, sometimes for carving interesting things, and sometimes just to give your hands something to do while you were thinking. While there are specialized knives for wood carving, most sharp pocket knives can be used for whittling. A dull knife will not work well, making it much harder to shape the wood, and much more likely that you will cut your finger instead.
The first thing to do is to eat the popsicle so you can get at the stick. Of course you can buy popsicle sticks from a craft or hobby store, but what is the fun in that? Once all of the icy treat has been removed from the stick, we will use the pencil to mark the parts that we want to remove. Starting about an inch from one end, draw lines from each side that come inwards towards the end, as seen in the photograph.
Now comes the part where you have to be careful and patient. We are going to whittle away the wood that is outside those lines. Hold the piece of wood in your left hand (if you are right handed), and with the marked end pointing away from you. Holding the knife in your right hand, with the sharp edge pointing away from you as in the photo above. Always cut away from you, never towards your hand. You want to cut away very thin slivers of wood. Trying to cut too thick a slice will split the stick. Once you get the stick close to the right shape, start cutting even smaller slivers, shaping and rounding the end. Don't worry if you make a mistake along the way. You can always eat another popsicle to get another stick.
Your Whistle Stick is now complete. To use it, press your finger and thumb together, as if you were going to snap your fingers. You can use either your first finger or your middle finger. Place the whittled end of the Whistle Stick in between finger and thumb. Then snap your finger. The Whistle Stick should fly away, making a strange, whistling sound. You may have to practice a few times, and the video should help with how to hold it and what to expect. At the end of the video, I try the same thing with a tongue depressor which is quite a bit wider than the popsicle stick. Notice the difference in the sound.

Once you have played with the Whistle Stick a bit, then it is time to do some scientific thinking. Why does it make that sound? Why does the tongue depressor make a different sound? Listening to the two, you should be able to figure out what is happening. Give it some thought, and some experimentation (which may mean that you need more popsicle sticks), and we will look into that deeper next time.

Have a wonder-filled week!

Link to Whistle Stick, part 2

Today I was playing with sound experiments, and had so much fun with this one that I thought I would share it.  It is based on the original phonographs, which used a very similar setup to play recordings of music or voices.  To try this, you will need:

• 2 needles or pins
• paper
• a piece of cardboard
• tape
• (optional)  an old phonograph record.  Use one you don't mind damaging.

IMPORTANT!  Using this with a phonograph recording could damage it.  Do not try this with a recording that is important, valuable, or that will get you in trouble if it is scratched or damaged.  Flea markets are a good place to pick up an old record to try this with.

The first thing we need to do is to make a paper cone.  Roll the paper into a funnel shape.  Shape it so that the small end is almost closed, and the large end is as large as possible.  Use a piece of tape to hold it in place.

Stick one needle through the small end of the cone, about 1/4 inch from the end.  This will be your phonograph.

Let's start with the needle that is not through the cone.  Hold it in your fingers, and scratch it lightly across a piece of cardboard.  Listen carefully to the sound that it makes.  

Try the same thing with your phonograph, holding it by the paper cone, and trying to use the same amount of force that you did with the first needle.  You should hear a much louder sound.

Why is it louder?  Remember that things produce a sound by causing the air to vibrate.  The more air you can vibrate, the more sound you will produce.  As you moved the first needle across the cardboard, the point would catch on a rough place, and then spring free as you moved your hand forward, catching again and again.  This caused the needle to vibrate.  The vibrating needle caused the air around it to vibrate, producing a small sound.

When you tried the same thing with your phonograph, the needle also caused the paper cone to vibrate.  The paper cone has a much larger surface, which lets it vibrate more air, producing a louder sound.

If you have an old phonograph recording that you are willing to sacrifice, try moving the needle along the grooves in the record.  DO NOT USE YOUR PARENT'S RECORDS WITHOUT ASKING! You should hear the recording play.  Can you move the needle at the right speed to hear it correctly?

The early phonographs did not use electricity.  Instead, they worked just as your cone does, with a needle vibrating as it moves across a surface that has bumps and grooves, and a large cone to amplify the sound.

If you want to experiment some, try using a piece of paper that is not rolled into a cone.  Stick the pin through one corner of the paper, and try scratching it across the cardboard.  Does it work?  Compare the sound that it makes to the cone.  Is one louder?  Is one more directional than the other?  You could also try using a sheet of aluminum foil, a paper towel, a sheet of cardboard, and other materials instead of the paper.  What properties (density, stiffness, flexibility, etc.) give you the best sound?  With the proper approach, this could be turned into a very nice science fair project.  Hmmm.  I wonder how well it would work with one of those yummy sugar cones used for ice cream?  Sounds like a good excuse for a trip to the grocery!

Have a wonder-filled week.

I was recently videotaping on Sanibel Island in Florida. Looking at the video later, I saw something that I had not noticed while taping. In one frame when I was photographing distant lightning, a streamer of spark about three feet long can be seen leaping upwards from a nearby car. Luckily, this spark did not connect to the lightning bolt, but it showed that the potential was there for me to have a much closer experience with lightning.

This experiment is closely related to my close call with the lightning. It will give you an idea about why that spark jumped upwards. You will need

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This is an experiment that was sent to me by Bob Burk a few weeks ago. His son showed it to him and he was nice enough to pass it along to me. With the holiday season upon us and New Year's just around the corner, I thought this would be a fun one to try. You will need:

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As I am having problems with my voice this week, I thought we should have an experiment that related to the vocal cords. This one should give you an idea of how your vocal cords work.

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If you have ever played with a tuning fork, you know that they are interesting and fun, but they can also be expensive. For this week's experiment, we will use a regular fork from your kitchen to produce a beautiful tone. For this experiment, you will need:

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This project has science fair potential.

See the video version here

Any time you hear a sound, it is because something is vibrating. Place your fingers against your throat and hum. You will feel your throat vibrate. We usually hear sounds from vibrations that travel through the air, but solids can be much better at carrying vibrations.

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Link to Part 1

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