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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

This week, we are going to produce some floating bubbles. Our bubbles will be filled with ordinary air, and will be floating on a layer of a heavier gas. To try this, you will need:

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This week's experiment is one that I played with while waiting for one of my programs to start. I started with one balloon, and then added another. As I tried different things, I began to have fun with the charged balloons. To try it yourself, you will need:

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Through Rose Colored Glasses

What is it really like to look at the world through rose colored glasses? Not nearly as strange as when you finally take them off!

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The Smell of Money

A magic trick that can teach about observation and the senses.

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Straining a Flame

Why can't a flame go through a metal screen? Try this fun experiment to explore the science of combustion and heat.

Why does putting a plastic bag over a credit card make it scan better?

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This week's experiment seems to be a magic trick, but the basic idea is very useful. It is the idea behind the self sealing tires that seal themselves after you run over a nail. To try this, 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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For this week's experiment, I wanted something that related to hurricanes. I settled for one that is based on fast moving air and differences in air pressure. You will need:

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This week's experiment should be familiar to any of you that have ever cooked pancakes. As my mother taught me, and as you will find in most cookbooks, in order to tell if the skillet is hot enough for pancakes, you dip your fingers into some water and then shake a few drops onto the skillet. If the drops just sit there or if they hit the skillet and boil, then it is not hot enough. As the temperature of the skillet increases, you reach a point where the drop of water seems to bounce and glide around the skillet. Then you know that the skillet is hot enough for pancakes. This is called the Leidenfrost Effect, and that is what we want to observe now.

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For this week's experiment, we are going to make a ball of oil. Don't worry, this is not nearly as messy as it sounds. You will need:

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