Fun Science Demonstrations
Professor Gizmo (Amazing Science Presentations) gives expert video advice on: How do we make sounds that are both high and low?; How do my eyes play tricks on me?; What is the difference between a solid, a liquid and a gas? and more...
How do we make sounds that are both high and low?
How to make sounds high or low; this is a neat little topic to take look at. Think about a piano or a guitar (especially a piano); if you take a look at the longer strings on a piano, they're usually the lower notes and the shorter strings inside the piano, they are the higher notes, and we can show you that with a couple of items. This is a slide whistle. Now, we blow into the slide whistle, and there's a small chamber in here where the air vibrates. If we make that section where the air vibrates longer, it makes the note lower, and if I make it shorter, it makes the note higher, so it sounds like this [Professor Gizmo blows the whistle, pulls the slider down and makes a sound that starts high and becomes low]. You can see how the size of that space in there changes. It's easy to remember because both start with an L; longer is lower. Now this, is a little demonstration that you could do at home, that you would be very careful with, but it's just simply a straw. I like to call it this "the straw oboe". Now, I flatten this end out just slightly, and pull it between my teeth gently to flatten it out. Then, you take scissors and you cut a little wedge on both sides like this, and like this [he cuts the straw] and then you blow into this end [a noise is produced]; pretty low sound, right? Now, we can change that by changing the length of this tube; remember longer was lower, so if we make it shorter its going to be higher. [Professor Gizmo blows into the straw. As he is blowing he takes the scissors and snips off sections on the straw, making the sound higher with every snip. He accidentally snips his nose] Oh! You got to be careful.
How do vibrations make sound?
Sound is caused by a vibration. Now, some of you might be saying – What's a vibration? Well, vibration is just something that goes back and forth, back and forth. Now, if the object vibrates fast enough, it's going to disturb the air. If the air vibrates, our ears are sensitive enough to pick that up. Now, to show you what a vibration actually does, we have a tuning fork – and this tuning fork will vibrate at 426 times every second. So, when I hit this, these two ends will vibrate. Now, it's vibrating in the air, and we can't see what the air is doing to us, but our ears can pick it up. So, let me just hit this and listen. (Sound) Now, when it's vibrating, you might be able to see these ends are a little blurry, but you're not going to see what's really happening to the air. But, when I take this and touch this to the water – water's a lot thicker than air, so we're going to see what affect this actually has on water compared to the air. (Sound) And, that vibration actually disturbs the water enough for it to splash out. So, we have lots of vibrations going on here – 426 vibrations every second – moving the air – we can't see it, but when it touches the water, we can see what the vibration does to the water. Many, many things cause vibrations. One of the interesting things is this cup. In fact, when you look at this many of you might remember this as the old telephone. If we have another cup on this end, what we might have is a telephone. Now, when your voice vibrates – your voice actually vibrates the air and you talk into the cup, your voice vibrated the air, the air vibrates the cup, the cup vibrates the string, and if we had a cup on this end, this would also vibrate and the person could hear it – so, you could talk back and forth to each other. Now, I also want to show you this. This is just a cup with a string in it. You look at it and you say – well, this is just a cup with a string. But it was actually invented – in fact; this was invented in two places of the world many, many years ago. In South America, when this was invented, they made it with a wooden cup, they had a wooden stick on here, and when they pulled on the stick, it vibrated and made a sound. And, they still use this in South American music. It's called a cuaga. Now, with this one, we can pull on the string and actually get the string to vibrate, then the cup to vibrate, and we can hear it. So, instead of using it as a telephone, we're going to use this to create sound. So, if I take the string, and I pull on it like this, it almost makes a breathing sound, like Darth Vader. Now, we can change how this vibrates because my hand is sliding pretty smoothly on the string. Now, we can change how this vibrates by using a wet sponge or just making the string wet. And, when I put this on here, and pull on here, it makes a different sound. So, the vibration now is caused by water on here and water lets our fingers slide and it catches and it slides and it catches. So, if I pull on this again, you can hear what it does. Now, we can make cups vibrate differently. This cup has a special string on the bottom. In fact, it's not even a string – it's a ribbon of plastic. On the ribbon of plastic is actually a lady's voice recorded. And, there's little bumps on this plastic. In fact, I can see the bumps in this area and what this plastic ribbon will say is “Science is fun”, so let's listen. Did you hear that? Science is fun. Isn't that cool? So, I am vibrating this by pulling my thumb down. It's going over the bumps and actually reproducing that lady's voice. It works like a record.
How does sound make things look better?
So, what am I doing? It's hard to figure out when something is happening around somebody but if you add sound to it it really changes things and that's why they spend thousands and thousands of dollars to add sound to movies and cartoons because sound makes things look better. Now, you saw me just before. Little tiny whistle. See what sound does? Sound makes things look so much better.
What is "Bernoulli's principle"?
Bernoulli's principle definitely has to do with aeroplanes. Bernoulli was around about 100 years ago. Now, he did not invent this he just discovered it. It was called Bernoulli's principle named after him. These are not exactly Bernoulli's words, but here's his principle: basically he said that where there's moving air there's low pressure. Okay, where there's moving air there's low pressure. Now, a couple of ways to demonstrate that: this is a simple little plastic tube and in the end I have a golf tee. The golf tee has been modified. There is a hole that has been drilled in it so air can come out. So, what I'm going to do is take this ping pong ball, which is very light, and I'm going to hold it over that hole and blow air through there, and I want you to watch what happens. That ball stayed up in that column of air, and it stayed in there because of Bernoulli's principle. Now, he said where there's moving air there's low pressure. The air hits the bottom of the ping pong ball and it goes all around the sides of the ping pong ball, so all around the ping pong ball we have moving air which is low pressure. Then, all the other air in the room around it is high pressure. So, if the ball falls one way the high pressure pushes it back. If it falls another way high pressure pushes the ball back. So, Bernoulli's principle works very well in explaining how that works. We also have this; a corrugated tube. Now this works together in showing two things; it shows Bernoulli's principle and also sound. This has a corrugated construction and as air goes through there the air will be vibrating; oscillating against the sides and making a sound. Now, when I spin this around in the air (let me just show you slow motion wise) you can see the end of the tube actually moving through the air. So, in reality we have moving air right here, and where there's moving air there's low pressure. As you spin it around, the high pressure in this room tends to want to fill that void. Since some of the air actually goes in to the bottom of the tube (well, as it travels through the tube) it makes a sound and that's how we can tell air is going through the tube. So, here we go with Bernoulli's principle making a tube sing. Cool huh? That's Bernoulli's principle remember; where there's moving air there's low pressure.
How does Bernoulli's principle keep airplanes in the air?
Bernoulli's principle. Yes, it's hard to understand, but it really is responsible for keeping aeroplanes in the sky. Now, every time I have done something with Bernoulli's principle, or looked it up on the internet, or found it in a book, they always have a little picture of an aeroplane flying through the sky. It shows the aeroplane in a cross-section, and it shows the wings, and the wings are shaped so that the air goes across the top of the wing faster than the bottom. The air is moving across the top of the wing, and Bernoulli said where there's moving air there's low pressure, so we have low pressure on top of the wing. Air on the bottom of the wing is not moving as fast, and that's high pressure. So, that actually gives the plane lift and keeps it in the sky. Now, to go along with that, we have this little demonstration. It's simply a pen or a pencil, and you tape a piece of paper on it, just like a 2-inch strip, and this is supposed to represent the aeroplane wing. Now, my breath blowing across the top is going to represent the air blowing across the top of the wing. So, I hold this to my mouth, and it's going to be below my mouth. I'm going to blow across here. Right here we have moving air, and moving air is low pressure. On the bottom of this "wing" is going to be high pressure, and so this should come up in the air. So if I do this... [He blows twice and the paper flutters up] Now, did you see how that lifted it up? Now, I'd really like to do this and show more people, but then, I'd need a bigger piece of paper and more air. A bigger piece of paper and more air. I wonder... bigger piece of paper, more air. [Wavy dissolve. Professor Gizmo is standing outside.] Let's see. Bigger piece of paper, more air. Bigger piece of paper, more air. [Professor Gizmo picks up a mechanical blower with a roll of toilet paper mounted in front.] Bigger piece of paper, more air. Ho, ho, ho! Let's try this! [Professor Gizmo flips the on-switch. The toilet paper streams high into the air. Professor Gizmo gives gleeful laugh.] Hoo-hoooo! Ohhhh! Ohhhh! Ho, ho! It works! It works! Alright! Yahh! It works! Yay!!
How do airplanes stay in the air?
A lot of people wonder why aeroplanes can stay in the air, and it has to do with Bernoulli. Bernoulli's principle is partially responsible for keeping aeroplanes in the sky. Bernoulli said, where there's moving air, there's low pressure. This little toy might be able to explain that. This is a little helicopter toy, and it is powered by a balloon. When I blow the balloon up, I have air pressure in there, and when I attach it here and I let some of the air out, you'll hear a noise. Now, not only noise is coming out of there, but some of the air is going through each of these blades, out this way, causing the helicopter to spin. As it spins through the air like that, the wind that's going across these wings, like an aeroplane wing, has to go over the top of the wing faster than the bottom. So, if we have moving air going across the top of the wing, and moving air is low pressure, what do we have on the bottom of the wing? We then have high pressure, and that's what gives it lift. So, let's just try this. Lift off! Bernoulli's principle did it again! It's good to know that planes stay up in the air. They do come down, too, because they have to land. All an aeroplane does when it lands is it loses speed. Air doesn't go across the wing as fast and it loses its lift and it starts to come down, and it's coming down because of gravity. Now gravity's a force between a very, very large object such as the planet earth and anything that's near it, and it will draw it to it. We can kind of demonstrate this with a helicopter. A helicopter will go up, thanks to Bernoulli's principle, and gravity might bring it down. It did! Gravity brought it back down! How cool!
What is a "polymer", and how do they work?
Polymers are a fun aspect of chemistry. Poly means "many" and mer is a part. So polymers are made up of many, many parts. When you mix polymers together, parts hook together and form long chains of chemicals. The long chains of chemicals change the make up of the substance. Now, what we have today is a polymer that is a white powder and we're gonna mix it with water. What I'll have to do first is pour the polymer into a cup. Then we're going to take water, and pour water into this cup to mix water with the polymer. Then we're going to tip it upside down, and we should have snow and ice. So this polymer actually has taken all of that water that was in that cup and combined it within itself to form this powder. This is used for imitation snow. In fact, you can buy this at stores. The only trouble with this is that it has a lot of water in it, and if you let it sit too long it might start to get moldy. Now, the other aspect of this is you can find a powder very similar to this in diapers. Inside the diaper they use this polymer so that when the baby wets, the polymer absorbs all the moisture. When you take the diaper off, you're dealing with a heavy diaper, not a wet diaper. So the plymer has very practical uses. They used to use these polymers to coat seeds. So when you put the seed in the ground, the polymers attract the water. Water goes around the seed, and it makes the seeds grow a lot easier.
What is "static electricity"?
Static electricity; that's a fun one. I'm positive everybody has done this; where you've run across the carpeting, and you're shuffling your feet real fast, and then you go up to a doorknob and you touch it and you get this spark. Well, what's happening is when you're rubbing across the floor, you're picking up electrons. Then, when you get to the doorknob and you reach out, the electrons jump from you to the doorknob. Well, there are lots of things that can show that. In fact, if you take a balloon and you rub it on your hair, and then you stick it to a wall, it'll stick there. Now, this is a nice demonstration, and you only need three things to make this work. You need a PVC pipe, you need rabbit fur, and this is a styrofoam ring, which is basically material that's used for packing things such as DVDs or whatever. I cut the styrofoam into a long strip and taped it together to make a hoop. Now, to make this work, we simply are going to take the rabbit fur, and we're going to put a charge on the styrofoam ring, and then we're going to put the same charge onto the PVC pipe. Same charges will repel each other. So when I rub this way, I'm adding a charge to the styrofoam ring, and now I'm going to add a charge to the PVC pipe. They're both the same charge, so they should repel each other [Professor Gizmo picks up the styrofoam ring with the PVC pipe and lifts it into the air; the styrofoam ring starts floating about the pipe as it repels)...and they do. Look at that. So, they're both like charges, and they are repelling each other. So, when I put the stick under there, it's trying to get away from me!
How do my eyes play tricks on me?
If you feel like your eyes are playing tricks on you, it could be real because our eyes will play tricks on us. Some people call them optical illusions. Now, if you want to look at this, I have two identical pieces of plastic and one is yellow, and this one is red. Now I'm quite strong so I can actually pull this yellow one from behind and make it longer and bigger. Watch, I'll pull. [Professor Gizmo pulls the yellow piece and extends it past the edge of the red piece] There. Now, I will show you. Look at how much bigger it is. I did that. Now tell you what, we can put it back the same size. Oh what, you want to see me do the red one? Well, sure! Here, turn it around and I'll pull the red one, I'll make it bigger. [Professor Gizmo pulls the red piece of plastic and extends it past the edge of the yellow piece.] There, it looks bigger. Let's put is side by side. Yes! It is bigger. Now, you know what, our eyes are just playing a trick on us. It's really not bigger. Watch, I put them back together and they are exactly the same size. OK. Now, if I put the red one down below, guess what, the red one is bigger. If I put the yellow one down below, the yellow one's bigger. Our eyes are playing tricks on us because we look at this object as our eyes see it, and they're just turning it around. You could probably do this with bananas too, because they are the same shape and If I turn it this way, [Professor Gizmo hold the pieces of plastic up, the yellow piece on the right and the red piece on the left] one looks bigger. If I swing around like this... [Professor Gizmo swaps the pieces around so that the red piece is now on the right] So, you can't always trust your eyes because sometimes they're playing tricks on us. The reason this is happening is because of perception, OK When we have it like this [he puts the pieces one on top of the other] you can see, if I turn this around, that they are both identical; they are both exactly the same size. When I go down like this - one over the other - this end appears to be short over here and short over here but when I move it up it's exactly the same length. This is because of where it falls on this elliptical shaped object here; it makes our eyes go "Oh, well look, there is a space there and a space there; this one must be bigger." So, our eyes are just tricking us into thinking that this one is bigger. When I switch it around, look again, identical size. I put this one below it, and we now have that same illusion. That's why our eyes play tricks on us.
What are forces and can I multiply them?
A force is a push or a pull. How can you get more of a force? You can actually multiply forces together to increase the force. Here's a little example of that. We're going to use a couple of tennis balls to show you this. First of all, I'm going to hold this about eye height, and I want you to kind of watch how high it's going to bounce again. OK? We're going to record that. So I'll start it here; about this high? Try it again. Yup, that's about right. So, it was about this high. Remember that. I need two - oh! That's a big tennis ball! OK. Well, let's see how high this tennis ball bounces. We'll put this about eye height, drop it; it was about the same, wasn't it? OK. Yup. Just about the same. Now, we're going to multiply the force from this much bigger tennis ball, into this tennis ball. So, when I put this one on top, we're going to drop these together, and when I do that, the bottom one's going to hit the table, it's going to start coming up, and it's going to apply its force all into this tennis ball. This tennis ball is going to go up; we'll see how high it will go up. This one won't go up quite as high. So, we'll watch. Whoa! That tennis ball went! Now this one, it didn't bounce as high, because some of the force of this tennis ball was applied into that tennis ball. That's how you can multiply forces.
What is "Newton's First Law"?
Sir Isaac Newton. He was born over a hundred years ago on Christmas day and a lot of people know Isaac Newton for his discovery of gravity. Well, we're going to talk today about Isaac Newton's First Law of Motion. Now, In that First Law of Motion, he said, "When an object is in motion, it wants to stay in motion and when an object is at rest, it wants to stay at rest until acted upon by some outside source". That's a lot of words to remember so I have to do it my way. This is my interpretation of Sir Isaac Newton's law. I call it the 'Law of Laziness' and I say that because things like to keep on doing what they're already doing. If they are not moving, they want to keep not moving. If they are moving, they want to keep moving unless acted on by something else. So, the Law of Laziness. Let me show you just a quick demo of the Law of Laziness. Now, this is an empty jar and we're going to place a card on top. Just a regular playing card and you can use a penny, nickle or I have a little nut here we're going to place on top. Now if I take this card and get it out of the way fast enough, that nut that's on there is so lazy that it's not gonna want to move. So I can probably pull that card out, the nut's not gonna want to move and once the card's out, the only thing it can do is drop into the jar. I'm going to move it out of there very quickly, by snapping a pen across the card and that shows you that, that is really a lazy object and actually heavier objects are lazier objects. Now, I'd like to show you this a little more dramatically. That was kind of fun, but let's do it a little better. Now, I need to set this out of the way and we're going to use three little tumblers that have water in them. I have water in them because the objects that are going to drop in there, I don't necessarily want them to break or break the tumblers. The next thing we need is a pizza cardboard. Now, this pizza cardboard has three areas marked on here. This is where the tumblers would be. Now, I'm going to line this up so that, I have to get down this way and line it up so that they are directly under where I am looking and then I want to go this way and make sure they are under there so that when the objects drop into the containers, everything will be fine. Now, we're going to set the objects on top of these rolled up playing cards. Ok, we'll just set those there and then we're going to use these objects. These are eggs. These are raw eggs. So hopefully we don't have a mishap and the eggs drop directly into the container below. Each egg, and maybe they won't even break. Ok, I can't, I have tried a number of times but I can't pull it out fast enough so I have to use another method to do that. I'm going to use a broom. Just a regular broom. I'm going to take the broom and place it on the floor and bend the bristles so that this kind of acts like a spring. Ok now, here' s what we're going to do: with the broom in this position, I'm going to pull it back. The first thing the broom is going to do is hit the cardboard and the cardboard is going to go flying. So don't watch the cardboard. Then, once the cardboard is out of the way, this is going to continue but it's going to hit the table and the table is going to stop it from hitting any of the eggs. Once the cardboard is out of the way and this is stopped, hopefully, the eggs will drop directly into the cups and not break all over. Ok. We'll pull it back. We'll count to three. One. Two. Three. Yeah! It worked! I'll show you too that these were not just hard boiled eggs. These were raw eggs. Yes. Newton's First Law. The Law of Laziness.
What is "centripetal force"?
Centripetal force is an inward pull. It's almost like if you were thinking about a satellite orbiting the earth and the earth's gravity would create this inward pull. In fact, we could use a simple science toy to demonstrate this. If you take a balloon, this is a clear balloon (you can use any balloon to do this) and if you just go into mum or dad's little area where they keep old left over parts, just grab yourself a six sided nut and take the nut and drop it into the balloon. By the way, this is a very inexpensive toy. Once it's in there, you blow up the balloon. Now the balloon is going to represent the centripetal force on the nut and the nut is going to represent the satellite going around the earth. The earth would be positioned inside, right in the centre of the balloon. Now, once we get this nut moving it's going to make some noise. It's going around like this; it is moving around in a circle mainly because the gravitational pull of the earth keeps the satellite in that orbit and this balloon is representing this gravitational pull. Now, as this nut rolls around, you notice that it makes a little noise. If we roll this around again, it's making noise because we have a six sided nut; it's not very smooth, and every time it rolls over one of the bumps it makes a noise. It's almost like your car tire rolling over the bumps on the side of the road if you get off too far. OK, so it makes that same noise. Now, we can do the same thing and get a better look at the satellite end with a nickel and a balloon. So, we'll put the nickel in the balloon. This increases the value of the science toy by four cents I think. Now, we'll put this in here and then we'll blow this up and tie a knot in this balloon. Now, the nickel is going to represent the satellite going around the earth. The balloon is representing the gravitational pull keeping it in orbit, and as it's going around like this, you can see the satellite, our nickel, going around and the earth would be centred right in the middle of the balloon. The balloon is actually kind of representing the earth's gravitational pull, pulling it in. As soon as our gravitational pull balloon would break, the nickel would fly off into space.
What is "centrifugal force"?
Centrifugal force is kind of like the opposite of centripetal force. And centrifugal force is a force pulling out. The best answer I can think of is they use to have devices were they would train astronauts and they would sit in these little compartments and it was like being put in a blender and they would spin around in a circle and that outward force will actually pull their face back like this and make them really look ugly and strange and that outward pulling force is centrifugal force.
What is the difference between a solid, a liquid and a gas?
Solids, liquids and gases. The states of matter. Now that's a really neat topic. When you start thinking about solids, liquids, and gases, most of us know what they are. If I mention a brick, you'd say, "solid". If I mention chocolate milk, you'd say, "liquid". I mention helium, you'd say, "gas". However, sometimes things are really kind of mixed up. If you think about ice cream, is it a solid, liquid or gas? You know, when I buy it I want it to be a solid, but it can change. So, states of matter: you could have water as a liquid, you could have it as a solid, you could have it as a gas, and it changes depending upon the temperature. Now, one of my favourite things to use when I'm talking about solids, liquids and gasses is dry ice. Dry ice is really, really cold. In fact, it's colder than where I'm from. It is a hundred and nine degrees below zero. It is so cold. Now, it is a very strange substance, too. In fact, what is it called? It's called dry ice. It's made out of carbon dioxide, but it's got its name from the fact that it never melts. It never, ever melts. It goes from a solid directly to a gas. It doesn't melt, which is kind of neat. Now, since it's going from a solid to a gas we can show you some things with it. At a hundred and nine degrees below zero, I'm wearing gloves. I'm not going to touch it, because my hands could freeze to it. Now, this is a small piece of solid carbon dioxide. The carbon dioxide is a gas, and you can see a little bit of the smoke coming off. It's really not smoke. This is so cold it's actually forming a little cloud here. It's condensing the water that's in the air, and it's turning from a solid to a gas, and all sides of it are doing that. The top is, the bottom, the front, the back. So, if I set it on the table it's actually creating itself a little bit of lift, almost like an air hockey table. There's air blowing up from the bottom of the air hockey table and it lifts the puck up so it floats and it moves really fast. Well, this is doing that too, and I have to just slide it around a little bit; look! It is floating on its own layer of gas, just like an air hockey puck. So, it's turning from a solid into a gas. Now, we can show you some other things that work with this, too. I'm going to need a hammer. Now, I'm going to take this hammer and I'm going to take and make some of this dry ice into a little pulverized state. Let me just hit some of this, crushing it up into almost rice size grains, and then I'm going to try and scoop up a little bit of this material, and then we'll take a spoon and we're going to add some of the dry ice to the balloon. We'll just put some in there. In fact, this could even be called a science for lazy people, because I'm very lazy and once I get some dry ice in here and tie a knot in this end, it's going to start to do exactly what I want it to do. When I tie a knot in there... can you see that balloon? It's actually getting bigger and bigger because the solid carbon dioxide, the dry ice, is turning into a gas. Now, this balloon will continue to blow up as long as there's dry ice in here, and this will get bigger and bigger as we just let it sit. It's turning from a solid into a gas, and the gas that's in there is carbon dioxide. There's a lot in there, yet, so it's going to get bigger. Now, I can show you a couple of other things. On an old quarter there's an animal on the back, and that happens to be an eagle. Now, if I take this eagle and I put it on the dry ice, it will make the sound of an eagle. Listen! Did you hear that? Sounds just like an eagle. Try it again! What's happening is that the eagle's not making that sound, but what's really happening here is that the dry ice, turning into a gas, is causing this quarter to vibrate. Now, I don't know if you noticed when I started, but I held this in my hand a little bit to warm it up. Warm objects make the carbon dioxide turn from a solid to a gas faster, so when I set this down on there - I'm going to use my hand to show you this - if my hand is dry ice, and I push down on there, underneath that warm quarter, the gas is turning into a gas faster because it's warm, and it rises up, and I'm pushing down. The gas pushes up, and I'm pushing down. Well, this is happening very, very, very fast, and when it goes fast enough it actually vibrates. One more time. Oh, and look what I noticed! This side of the hammer is about the size of a quarter. Now, if we set this down on there, this might just make sound. Instead of hitting it, I'm going to set it on there. Listen! So, it's vibrating! It's also vibrating. I would like to show you that we can make a big cloud with carbon dioxide. Now, if we can get this dry ice to turn into a gas faster, it would give us a lot more cloud, and one of the ways that it actually makes a cloud is with moisture. Now, to cover both bases - to have this turn into a gas faster - we need heat, and we need moisture. In this container I have hot water. So I'm going to take the hammer and make some smaller pieces, not real tiny, just break it up into some chunks, and then we'll take these pieces and put them in here, and we will make a cloud. Ho-aa, ha-a, ha-a! Look at that! W-ha-a-a! Is that cool, or what? Ha-a, ha-a! Look at that! Wow! Look at that go! My goodness! Ha, ha, ha! It's bubbling all over! Ha, ha! Isn't that great?