Mr. O! A Video Blog from the Children's Museum of Houston » Cool Links

Singing Glasses and Sympathetic Resonance

Mr.O — Wed, 25 Jan 2012 20:21:15 +0000

Miss Manners definitely will not approve of this video or its sequel, but science (and O Wow Moments) must not be held back!

In this episode, we’re going to explore sympathetic resonance. But, before we can do that, we first need to explore the science of making glasses sing. It isn’t that hard to do – get a wine glass (kids, make sure to get your parents’ permission first before attempting this experiment; husbands – get your wives’ permission). While crystal makes excellent sounds, it is more fragile than glass and more expensive. So, since glass will work fine, I’d recommend using glass over crystal.

Once you have a glass, fill it about halfway with water, wet your finger and rub it around the edge. It takes a little exploration with how much pressure to use, but you should eventually get a great tone coming from it. It occurs because your finger makes the glass vibrate by constantly pulling a little, slipping, then pulling again.

Once you have your tone, get a second glass and repeat, this time adjusting the amount of water until the tones are as close as possible to the same. Remember – the key is the TONE to be the same, not the water level.

Sympathetic resonance is where the sound waves generated by one glass travel through the air and interact with the second glass to make it vibrate as well because they are “tuned” to the same frequency, or tone. You can see these vibrations by placing a toothpick or a small piece of straw on top of the second glass then making the first sing. How far away can you get and still make the second glass vibrate?

By the way, this is also how opera singers, according to legend, can use their voice to make a crystal wine glass break. They hit the same resonance, but at such high volume that the glass shatters. The first people I know to have recorded it on video were the Mythbusters as shown on this video. They had vocal coach Jaime Vendera break it which you can see him repeat on this video he posted afterwards.

Special thanks to our friends at Region’s Bank for making our O Wow Moments possible!

Ring Wing Glider

Mr.O — Mon, 19 Dec 2011 21:00:30 +0000

So we’ve done a few prior O Wow Moments here at the Children’s Museum of Houston on aerodynamics and planes like Blow Bernoulli Blow and Air Control. Basically, there are four forces that act on a plane:

Thrust – this the the forward force on a plane, ususally by an engine or, with paper airplanes, a throw
Lift – this is the upward force that allows a plane to fly, usually caused by the air under the wing pushing up on it due to the shape of the wing
Drag – this is basically friction, the force opposing the thrust on the plane which will cause it to slow down
Gravity – this is the force pulling a plane down

The key for a plane to fly is whether the thrust provided can generate sufficient lift to overcome gravity. So long as the design does that, it doesn’t matter what shape the wing takes.

Take ring wing gliders, for example. These gliders use hoops at either end to give them the lift they need to glide. So what kind of ring wing glider can you design?

Special thanks to our friends at Region’s Bank for making our O Wow Moments possible!

Stick Chain Reaction

Mr.O — Sat, 03 Dec 2011 12:15:45 +0000

I don’t normally watch reality TV or variety shows, so I missed out on the Kinetic King phenomena on the last America’s Got Talent. I only learned about it while doing research for this video. I actually came across this idea of using jumbo craft sticks to create chain reactions from some home movies of things that kids had made, which made me think that it was something that the Children’s Museum of Houston had to highlight on an O Wow Moment episode.

So, while I do show you how to do the cobra weave pattern to create a stick chain reaction, we also take some time to discuss the science behind why these reactions work – that wood is, in fact elastic, meaning it can deform and snap back to its original shape. Because wood is elastic, it can store energy in the form of potential energy when it is bent. Once released, that potential energy turns into kinetic energy.

When you make a long string of sticks properly woven, you have lots of potential energy stored waiting to be transformed into kinetic. However, the sticks have to be released in order, so rather than them going off all at once, they go off in a chain, like a row of dominoes falling.

And, for the Kinetic King (aka Tim Fort) – dude, you got robbed! Awesome talent – keep on making Rube Goldberg-esque creations.

Special thanks to our friends at Region’s Bank for making our O Wow Moments possible!

Getting a Sense of Smell

Mr.O — Thu, 11 Aug 2011 15:30:21 +0000

Our noses are amazing! Did you know we are nanosensors – instruments that can detect things billionths of a meter in size? That is basically what our sense of smell is able to do. And even though our noses aren’t as sensitive as some animals, they are still pretty sensitive.

Try out our Smelly Balloons experiment highlighted in this O Wow Moment episode from the Children’s Museum of Houston. Just add a little flavor extract to a latex balloon and you can still smell it! Create several and make a game to see how many people can guess correctly! But, just be careful about with whom you play the game…

Nanoscale science, the study of the behavior of particles that are billionths of a meter in length (think around the size of small viruses) and their potential applications is constantly in the news! But how to make sense of it all? Well the Children’s Museum of Houston is fortunate to be a part of the Nanoscale Informal Science Education Network (NISE Net) which has lots of information about nanoscale science and nanotechnology, including some basic introductory information as well as fun activities through its website at www.whatisnano.org. Many thanks to NISE Net who, thanks to a generous grant from the National Science Foundation, funded this O Wow Moment Episode.

Conducive to Conductivity

Mr.O — Fri, 25 Mar 2011 16:22:09 +0000

Why does electricity only flow through the copper on a circuit board? Simple! Copper, like most metals, is a conductor of electricity. That means that electricity can easily flow through it, as opposed to an insulator which is a material that electricity does not easily flow through, like rubber or plastic. And then there are semiconductors, but we’ll save them for a different episode.

So why does electricity flow easily through conductors? Well, that is a little more complicated to explain. Basically, think of electricity as energy that flows through electrons. [Reminder: electrons are the tiny, negatively charged subatomic particles that orbit around the nucleus of the atom - for more info, check out the static electricity episodes we did.] Some of the outermost electrons of metal atoms aren’t strongly attracted to the nucleus. This creates a sort of “cloud” of electrons that easily move around, thereby easily allowing them to transfer energy.

Let’s build a conductivity tester so you can test substances to see how conductive they are!

What You Need:

3 alligator clip wires (available at an electronics hobby shop like Radio Shack like these)
a 12VDC buzzer (available at an electronics hobby shop like Radio Shack like these)
a 9V battery
things to test

What to Do:

Connect one wire to the negative (-) terminal of the battery.
Connect the other end of the wire to the black wire on the buzzer, making sure the metal on the clip is grabbing the exposed metal of the wire.
Connect a second wire to the positive (+) terminal of the battery
Connect a third wire to the red wire on the buzzer, making sure the metal on the clip is grabbing the exposed metal of the wire.
To test the circuit, touch the two empty alligator clips together.
Place a material between the two clips to test them. Or, you can immerse the two ends into liquids to see how conductive liquids are.

What’s Happening?

In order for electricity to flow through a circuit, the circuit must be a complete loop – from the battery, to a device, then back to the battery, through a conducive material. This is called a “closed circuit.” The two open alligator clips act as a type of switch, controlling when the circuit is open or closed. When a conductive material is placed between the two clips, the circuit is complete and electricity can flow.

By the way, it is important to connect the buzzer as I described above. It is like a one-way street – electricity can only flow one direction through it. Connect it the other way and it won’t work! There are several devices like this, just like there are some that can electricity flow through either direction (like a light bulb).

Static Repulsion BONUS experiment

Mr.O — Thu, 17 Feb 2011 13:00:41 +0000

So in our most recent episode Static Repulsion, we finished up our three-part series on static electricity (including Static Shock! and Static Cling). To wrap the whole thing together we did a bonus experiment – sticking a balloon to a wall using only static electricity!

What You Need:

a balloon

What to Do:

Inflate the balloon pretty far – the more inflated, the better, but don’t let it pop!
Rub the balloon against your hair (or someone else’s) for about 20-30 seconds. It is best if you don’t have any gel, hairspray, or other product in your hair.
Touch the balloon to a wall
Let go of the balloon. It should stick!

What’s Happening?

This is a combination of all three episodes:

First, rubbing the balloon against your hair causes electrons to transfer to the balloon. So, the balloon gets a negative charge.

Then, by bringing the balloon close to the wall, the electrons in the wall are repelled (second half of the charge rule: “likes repel”) and move away from the area that the balloon is approaching. The lack of electrons there gives the wall a slight positive charge.

Finally, our charge rule applies again: opposites attract. So the negative balloon is attracted to the area of the wall that is positively charged, so it sticks until enough electrons disperse that the electrostatic force is insufficient to hold the balloon to the wall.

Good Vibrations

Mr.O — Mon, 17 Jan 2011 17:01:40 +0000

Just like the classic Beach Boys song, we’re focusing our attention on sound. Nothing fancy, just sound. How do we hear sound? Simple – vibrations!

Sound is created when something vibrates. Vocal cords vibrate to create voices, guitar strings vibrate to create music, doors vibrate when someone knocks on them – it all comes down to vibrations. The vibrations are energy and energy can be transferred from one object to another. So in all the above cases, the energy from the vibrations transfers into the air and the air, in turn vibrates until it reaches your ear. Your eardrum then vibrates, causing other structures in your ear to vibrate. All of this, in turn, stimulates nerves that send impulses to your brain which translates it all into how we understand sound.

Sounds complicated, and in the details it is beautifully complicated. But, at the heart of it all, sound is vibrations. Let’s create a visualizer to help see the vibrations as they travel through the air.

What You Need:

Tone generator – you can download them to a computer/laptop for free at several websites like this one or you can get an app for a smartphone like the free TONE app for iPhone here
2 inch, 8Ω, 0.5W speaker with leads (if possible) - I used one that I harvested from the Singing Fish Dissection I did a few months ago, but you can also get them at some electronic supply shops or online like at this website
3.5mm mono (or stereo, but mono is easier) male/male audio cable – available at most electronics stores or online like at this website
Electrical tape
Masking tape or glue
12″ round balloon
Large plastic cup – the one in the video is from a fast food restaurant that rhymes with “Mindy’s”
Scissors or Dremel tool
Wire cutter
Wire stripper
Salt – I just used a free package from the same fast food location as I got the cup
Soldering equipment (optional)

What to Do

Download the tone generator to your computer or smartphone
Strip about ½” – 1″ from the lead wires on the speaker.
Note which wire on the speaker is the ground (-) and put a piece of tape on it to help identify it easier as you continue.
Cut the 3.5mm audio cable in half (sometimes you can find audio cables with an open end with wires already exposed – this will be much easier if you can find that. If so, skip to #)
Strip back about 1½” of the outer insulation, exposing the interior wires.
If you have a mono cable, you will see two wires (go to #7) or a bunch of bare wires and an insulated wire (go to #10).
If two wires, strip both wires back about ½” – 1″
Connect the ground (-) wire (usually black) to the ground on the speaker by twisting the two wires together or soldering them together (if you know how). Wrap in electrical tape to insulate.
Repeat with the second wire to the other speaker lead.
If you see a bunch of bare wires, twist them all together. That is the ground.
Connect the wires to the ground lead on the speaker by twisting the two wires together or soldering them together (if you know how). Wrap in electrical tape to insulate.
Strip the second wire back about ½” – 1″ and connect it to the other speaker lead.
If you are using a stereo jack, you’ll see two insulated wire and a bunch of bare wires. Tape one of the insulated wires out of the way. Then do instructions #10-12.
Add some more tape to the connection between the speaker and the audio jack to make sure they can’t get accidentally pulled apart.
Test your speaker by hooking the audio jack up to your computer or smartphone and playing some tones around 500Hz. If you don’t hear anything, you may have a bad connection or the wires crossed.
Cut a hole in the bottom of the cup using the scissors or Dremel tool. Make it just slightly smaller than the speaker.
Cut the nozzle of the balloon off
Stretch the round part of the balloon over the top of the cup so it is on tight. It helps to have someone hold the cup while you do this.
Tape or glue the speaker to the bottom of the cup.
Flip the cup so the balloon is on top and the speaker is on the bottom.
Pour salt on top of the balloon.
Connect the speaker to the tone generator.
I recommend starting with tones in the 500Hz range and then change the values. Watch what happens with the salt.
If you don’t see the salt bouncing, no matter the setting, try turning up the volume.

NOTE: I’m going to create a different explanation of this with photos and post an update when that is completed.

What’s Happening

As I said at the top of this entry, sound is vibrations. But each sound has its own unique vibrations. A tone generator picks one specific tone at a time and creates that specific type of vibration. The vibrations from the speaker pass into the air and then into the balloon making it vibrate. The vibrations from the balloon make the salt bounce up and down on top of the balloon. Different tones create different vibrations which causes the salt to bounce in different patterns.

Some tones won’t create patterns. Even though you can hear it, the vibrations don’t translate as well into the balloon, so the salt won’t dance around like it does at other tones. This could be due to the speaker or the size of the cup. The air and everything is still vibrating, just not in the way needed to make the salt dance.

Molecular Gastronomy

Mr.O — Mon, 27 Dec 2010 21:41:08 +0000

Don’t let the name freak you out – Molecular Gastronomy is just the scientific exploration of food preparation. It isn’t just about cooking, but using science to create some fairly unique culinary curiosities. One of them, the one highlighted in our video, uses the same scientific principles used at the Rice University Center for Biological and Environmental Nanotechnology (CBEN) to create nanocapsules. We like doing this one at the Children’s Museum of Houston whenever we do homemade ice cream. But, before we get into the dessert toppings, let’s have a quick appetizer on nano!

To understand the basics of nano (shorthand nanotechnology, nanoengineering, nanoscience, etc.), we need to think small – really, really, really small. To get an idea, an average 4 year old is about a meter tall; nano is a billionth of that. Find the millimeter (mm) scale on a ruler and imagine a million lines between each of those. That is a nanometer (nm). Comparing a nanometer on a meters stick is like comparing the entire Earth to a marble. A virus is about 70nm long, a cell membrane is 9nm thick, DNA is about 2.5nm wide, and fingernails grow about 1nm every second. It is SMALL.

The “nanoscale” often referred to in discussions about nano ranges from 1nm-100nm. The interesting thing about materials when they get that small is that they start to demonstrate unusual properties – faster chemical reactions, remarkable lower resistance to electricity, etc. Nanotechnology involves the manipulation of materials at the nanoscale to take advantage of these unusual properties. When these properties are harnessed in large scale, they can have a huge impact. To learn about what’s so big about the super small, check out the website www.whatisnano.org.

Now, let’s get back to dessert!

What You Need

Blender
Measuring cups and spoons
Droppers or syringes
3 Bowls
Sieve or slotted spoon
Water
Dessert Topping (we used chocolate, but most kinds will work)
Food grade sodium alginate (available at several websites like this one)
Food grade calcium chloride (available at several websites like this one)

NOTE: You can actually purchase molecular gastronomy kids from several websites like this one.

What to Do

Blend ½ tsp. food grade sodium alginate with 1 cup of water until powder is dissolved
Add 4 tbs. of flavoring (in this case chocolate syrup) and blend again.
Pour into bowl and set aside. Let it sit for 20-30 minutes until the bubbles have subsided.
Pour 2¼ cups of warm water into a second bowl.
Add ¾ tsp. of food grade calcium chloride to warm water. Stir until dissolved.
Fill a third bowl with clean water.
Place a sieve into the calcium chloride solution
Use a syringe or dropper to drip the chocolate solution into the calcium chloride solution, letting the sieve catch the capsules. If you don’t have a sieve, you can use a slotted spoon to retrieve them, but it is harder.
Lift the sieve from the calcium chloride solution and put into the plain water for a rinse.
Drop onto your ice cream! (or dessert of choice)

UPDATE (1/7/11) – get a full lesson plan of this activity here.

What’s Happening?
The little capsules that are forming are being created by self-assembly. Self-assembly is just what it sounds like – when structures form automatically when provided the correct conditions. Snowflakes self-assemble as do other crystals and, in fact, all living things, too! The key is provide the right conditions. In this case, the sodium alginate reacts with the calcium chloride, causing the alginate to self-assemble a gel-like shell around the flavoring, creating a flavor-filled casing!

So what does self-assembly have to do with nano? Well, working directly with objects at the nanoscale is very, very difficult and very, very time consuming. Plus, it take a WHOLE LOT of production at that scale to create anything at our scale. But, using self-assembly, we could create large amounts of nanoscale objects relatively quickly. The key is to determine the right conditions for the assembly to occur! How sweet is that?!?

Strategic Thinking

Mr.O — Tue, 21 Dec 2010 14:00:26 +0000

We have a great game in our Cyberchase: The Chase Is On! exhibit at the Children’s Museum of Houston call Dragon Dilemma. It is based on an actual episode from the PBS Kids’ show Cyberchase (episode 118: Problem Solving in Shangri-La) where the Cybersquad had to beat the Hacker (if you aren’t familiar with Cyberchase, that means the good guys have to beat the bad guys) in a game of wits involving dragons.

Here are the instructions to recreate this game at home, only without the dragons (unless you have a few lying around…)

What You Need

15 objects – 14 that are similar and one that isn’t the same. For example, 14 pennies and 1 dime OR 14 paper clips and one rubber band OR 14 beans and one coin

The Rules:

Decide who will go first
Players take turns taking 1 or 2 of the same pieces from the pile
The goal is to NOT take the odd piece out (i.e. not have to take the last piece)

What’s Happening?

This is a game of problem solving and strategic thinking. There is a way to guarantee you will win every time, providing you can figure out and following the winning pattern. The video will get you started, but we’ll leave it to you to figure out the full pattern.

Once you figure it out, try modifying the game to figure out new strategies – what if you can remove 1, 2, or 3 pieces in your turn? Or only 2 or 3? What if you have more pieces or fewer? What if you add a third player?

As one of my all-time favorite cartoon characters Bugs Bunny would occasionally quip, “Time to employ a little stragedy!”

Welcome to the Third Dimension

Mr.O — Thu, 09 Dec 2010 17:09:21 +0000

For many people, when I say, “math,” they curl up in a ball trying to block out bad memories of solving for “x.” When I mention geometry, they curl up even tighter and block out bad memories of protractors and compasses while solving for “θ.” But there’s no reason for this! Math is fun!

Now stop dialing the phone for the funny farm. Math, especially geometry, can be a lot of fun. Let’s take nets for example. Nets, in geometry, are a two-dimensional representation of a three-dimensional object. Basically, that means that if you could peel away just the outside of an object and lay it out flat, you would have a net of the object. Think of it like a puzzle – what would a three dimensional object look like if laid out flat into two dimensions and how many ways could you represent it? Vice versa, how can you turn a two-dimensional picture into a three dimensional object?

Nets are especially important when beginning to learn about things like surface area and volume. Lots of professions use nets, like architects, designers, artists, and engineers. So let’s make some nets!

What You Need

Shapes – there are lots of ways to get your shapes:

Magformers – this is what we used for our project. They are shapes with magnets in them and are available at the Children’s Museum of Houston Fiddlesticks Gift Shop or online like the one here.
Other toys like Magna-Tiles or Hexabits
Or you can cut out your own shapes. You can get some ideas from the Children’s Museum of Houston Curriculum site or this one from the PBS Kids show Cyberchase.

What To Do

There are lots of ways to approach this activity:

You can build a 3-D object and try to figure out all the possible ways to make a net
You can build a net and see what 3-D object is created from it
You can build a net and have others guess what shape it makes

The possible ways to do this are numerous. Mostly, have fun and enjoy doing some math!