Yearly Archives: 2016

Bernoulli’s Principle Will Leave You Breathless!

What sorcery is this!? Science it turns out! This is a great example of Bernoulli’s Principle! In short, this states that moving air has a lower pressure. Imagine trying to dig a hole in a pool of water: as soon as some of the water gets moved out of the way, the surrounding water rushes in to take its place. Air does the same thing: whenever it moves, the lower pressure draws air in around it!

The cup and straw demonstration shows this nicely, and it’s also a great experiment to try at home! By taking each apparatus and blowing into it, we can see there is a pretty huge difference.

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Inside the cup, air is moving quickly. This causes a lower pressure inside the cup than outside, and air that tries to fill up the space suctions the balloon in place. Alternatively, the cup with holes in the sides allows the surrounding air to help out. Very similar to the Bernoulli Bag, nearby air joins in creating a larger column of air that can lift, and even suspend, the balloon.

bernoulli-loop

We know this looks like a trick, because it’s hard to tell from watching that he is exhaling vigorously in both cases. If you don’t believe us, definitely try it yourself!  Of course, it is possible to hold the balloon into the cup by inhaling, but it’s actually more difficult to suck up the balloon from a short distance away! The difference in pressure from blowing fast moving air into the cup is more effective at sucking up the balloon.

While Bernoulli’s Principle can be tricky to understand, it is very important! The fact that fast moving air has a lower pressure is one of the primary ways that airplanes are able to generate lift! The air going over the wing actually goes faster than the air below, which you can see in this very cool shot from a wind tunnel!

wing-wind-tunnel

Credit: Holger Babinsky, University of Cambridge

What Color is Lightning in a Beaker?

Thunderstorms can be incredible to experience. From the bright flash of lightning that is often almost to fast too see, to the immense crack of nearby thunder that can make your heart feel like it skips a beat, they truly are a demonstration of the power of nature.

lightning

Image Credit: NASA

They are also full of interesting science! For instance, lightning usually carries between 100 million and 1 billion volts of electricity! This allows it to jump all the way from clouds to the ground, and as it does so, some of that energy is transferred to the atoms in the air. This energy is released as light, which is how we see it. 

This means that it is the air itself which determines what the air looks like. On Earth, our air is made up of about 78% nitrogen, 21% oxygen, and a bunch of other gases like water vapor, carbon dioxide and argon. When we put electricity through it, it gives off a characteristic glow:

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The Oudin Coil generates up to 50,000 volts of electricity–much much less than a thunderstorm. This allows the electricity to jump about an inch, rather than the miles between clouds or to the ground of an actual lightning strike. However, when it arcs through the air, this still produces a similar look and identical color1.

Lets see what it would look like in a different environment. The beaker in this gif has a bunch of dry ice–which is just solid carbon dioxide–at the bottom. Unlike regular ice, dry ice doesn’t turn into a liquid, but instead skips straight to carbon dioxide gas! This gas is more dense than air, so the beaker ends up full of just carbon dioxide, which is a much different composition than our atmosphere. Check out what happens to the lightning in there!

color-change

Unfortunately, we can’t try this particular method with every gas for several reasons. First of all, not all gases are heavier than air. This would make it hard to keep it in the beaker. In addition, other gases might explode, or worse, if exposed to electricity with oxygen around in this way. Still other gases can be very toxic. Fortunately, we have some tubes of gas and a machine that puts electricity through it in a similar way. In this gif, the gas tubes are viewed through a diffraction grating which breaks up the light into the different colors of the rainbow contained within. This is actually a whole different branch of science which is used to figure out what elements different things are made of just by seeing the light that comes from them! Learn more about that here.

Written By: Scott Alton
1People actually report lightning to be many different colors. In general, nearby lightning will have a purple glow due to the composition of the atmosphere, and the central part will look white simply because it is so overpoweringly bright and doesn’t give time for eyes to adjust. Most other colors that are reported are because the lightning is being viewed from a long ways off and the light has to travel through dust, rain, haze, pollution, or other things that can change its color.

The Easiest UV Detector Ever

Science is full of words to describe the glowing process. We use bioluminescence for the glimmer of plankton, phosphorescence for the slow, ghostly shine of glow-in-the-dark toys, and fluorescence for pigments that emit light while exposed to just the right energy source.

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L to R: Fluorite sphere with phosphorescent coating, Don Mengason, Gemological Institute of America Inc.; bioluminescent phytoplankton on Vaadhoo Island in the Maldives, Kriss-Anne Gayle, Penn State University; mineral specimen fluorescing under UV light, James A. Van Fleet, Bucknell University.

Unless you live on a coastline rich with bioluminescence, fluorescence is the glow you’re most likely to encounter in everyday life. It’s present in white materials exposed to a blacklight and in the neon glare of highlighter ink. Tonic water appears colorless under visible light, but a distinct fluorescent glow appears when it’s bombarded with ultraviolet radiation!

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Tonic water contains a fluorescent compound called quinine. Expose quinine molecules to UV rays and they get excited, or gain energy. Excited molecules modify the absorbed light and eventually re-release it. Unlike the invisible incident radiation, the emitted glow is apparent to the human eye.

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Test this idea for yourself by taking tonic water outside on a sunny day! The blue glow is more obvious when compared to a glass of tap water– consider setting one up as a control. For more intense fluorescence, up the UV radiation by exposing your experiment to a blacklight.

Written By: Caela Barry

A Supernova For Breakfast (Almost)

Iron makes up less than one one-hundredth of one percent of the human body. Most adults contain just a few grams of this micronutrient. Despite its small presence in humans, it’s essential to our lives. Without it, oxygen can’t get from the lungs to the rest of the body. Iron also plays a key role in energy production and DNA synthesis.

The human body can’t produce all the materials it needs to function, so we get vitamins and minerals from food and supplements. We don’t often directly observe substances like iron, calcium, or vitamin A in our food because they’re present in such tiny amounts. Iron, however, has an unusual property. It’s magnetic, so it’s relatively easy to sort out from other ingredients!

IronCerealGif

Trace amounts of magnetic material in a whole food item aren’t strong enough to break free from the larger structure, even in the presence of a strong magnetic field, so it helps to start with something that can be broken down into small parts. Breakfast cereal is one food that’s commonly fortified with iron and is also easy to crush into a powder. Bring a powerful magnet near the powdered cereal, and iron-rich fragments jump out.

Supernova remnant 1E0102.2-7219

Supernova remnant 1E0102.2-7219, visible near nebula M76 in the Southern Hemisphere, is an approximately 1,000-year-old leftover from the explosion of a huge star. Credit: NASA/JPL/Spitzer Space Telescope

Iron plays an important part in the lives of stars, too, as the end product of stellar fusion. After lighter elements in a very massive star’s core have fused into iron, the core begins to cool and condense. Central cooling causes outer layers of plasma to fall violently inwards, collide with the iron core, and blast back out into space. This incredibly energetic explosion is where all elements heavier than iron come from, including calcium, which is also essential to human biological function. (Lighter elements, including oxygen, come from fusion inside smaller stars.) From hydrogen to carbon to iron and beyond, you are literally made of star-stuff!

Written By: Caela Barry

DIY Soap-Powered Boat

Ever filled a container with water, and then filled it some more? With a careful touch, you might have created a hill of liquid taller than the container itself. This works because of the surface tension, or cohesion, between water molecules. Place a small paper, plastic or cardboard “boat” on the water’s surface, and molecules will stick to it as well– that’s adhesion in action. Under normal conditions, adhesive forces on the boat pull it equally in all directions, so it doesn’t move on its own.

soapboat1

In this experiment, we use the chemical properties of soap to disturb the surface tension around the boat. Soap is made of polar molecules, which attract water. Introducing even a trace of detergent disturbs surface tension enough to unbalance the forces acting on a floating object. The boat appears to be propelled forward. In reality, the water behind it is no longer pulling against the water in front. The stronger pull ahead moves the boat forward!

soapboat2

This is a great project to try at home. All you need is a bowl of water, a small piece of paper or cardboard, (plastic bread bag tabs also work well), and liquid soap. Cutting a notch in the back of your boat can help to keep the soap where you want it. Dab a little soap onto the boat’s back edge with your finger, a toothpick, or a napkin, and watch your watercraft speed away!  Once surface tension has been chemically broken, adding more soap won’t cause a big enough difference to power your boat, so it’s a good idea to use a shallow pool of water and replace it each time you want to repeat the experiment.

Written By: Caela Barry

What is an Electromagnet?

Here at AstroCamp, one of our most popular classes is Electricity and Magnetism. At first glance, it might not be obvious how these things are related, but they are actually tied together through important physical principles.

To give you some evidence, let me introduce the electromagnet.

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This is really just a metal rod wrapped with a bunch of wire. Without any electricity going through the wire, it doesn’t do anything special. Now, let’s press the button and let electricity flow through the coil!

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What is going on? Well, to explain that we have to back up a bit. Let’s start by answering this question: What is electricity? It is the thing that runs our light bulbs, smart phones, computers, and air conditioning but what is it on a more fundamental level? What is happening?

asset-v1-pkuhighschoolph1019999_t1typeassetblockatom-light-640x360As you probably know, everything you have ever touched is made out of atoms, and these atoms have three parts: the positively charged proton, the negatively charged electron, and the neutral neutron. These charges determine how the particles interact; particles with identical charges push away while those with opposites attract.

Electricity, as you may have figured out by looking at the word, has to do with electrons. Electricity basically means moving electrons. However, physics has a bit of a surprise for us here. Whenever a charge is moving, it makes a magnetic field–if this word seems confusing, this is just what is produced by a magnet to push and pull on other magnets–around it in a circle. This happens every single time. You might be tempted to ask why, but I don’t have a great answer for you. This is just how nature is.

All we have done to make an electromagnet is sort of durn this trick on its head. By wrapping the wire into a coil, the circular magnetic field created every time an electron moves adds up in the middle. This kind of design is called a solenoid.

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This awesome illustration shows how the circular magnetic fields around each wire add up in a solenoid to make a strong magnetic field inside. All credit goes to Paul Nylander.

This might seem like a simple lab trick to convince you about the mysterious but very real connection between electricity and magnetism, but it turns out to be an incredibly useful and important design. Outside the obvious purpose of picking things up like the giant electromagnets at junkyards, electromagnets are used in speakers, hard drives, MRI machines, motors, generators, and many other things you might not expect!

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This is a view inside the Large Hadron Collider at CERN, the most powerful particle accelerator on the planet! This shoots tiny particles at very near the speed of light along a very precise track. While you might expect it to be the metal walls that keep the particles inside, the tiny particles would actually fly right out through the walls! So how do they keep those pesky particles in line? They steer them using incredible powerful superconducting ELECTROMAGNETS! Photo credit CERN.

Written By: Scott Alton

How do Geysers Erupt to Over 300 Feet?

Note: This experiment shoots boiling water into the air, and should not be attempted at home without proper training and safety equipment!

Geysers are one of nature’s most incredible spectacles. In the most powerful eruptions, water can be shot over 300 feet–or the length of a football field–into the air!

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The Castle Geyser in Yellowstone National Park erupts. Water droplets in the air produce a picturesque rainbow against the blue sky. Photo credit: Brocken Inaglory

But just how do these things work? Geysers require some very specific conditions, which means that they only exist in certain locations. In fact, over half of the world’s geysers live in Yellowstone National Park. To find out why, let’s look at how one of these actually work!

When a geyser erupts, it is going through something known as a hydrothermal explosion, which sounds awesome, if a little complex. Luckily for us, the key to this is something familiar: boiling water. Even more fortunate, most of us have never seen a violent eruption of steam from the stovetop while cooking dinner.

The key to this is something called superheating. Most of us are familiar with the phases of matter. In everyday life, many of the things we see exist solely in a liquid, gaseous, or solid state. However, any material can be in any of these states depending on its heat and pressure. Below is the phase diagram for water. On the left is pressure which gets higher as we move up the diagram, and on the bottom is temperature, which increases as we move right.

Phase-Diagram-Water

Phase diagram for water. In geysers, high pressure can push water’s boiling temperature from 212℉ to almost 500℉, well above the temperature required to burn wood! Image from Pearson Education.

To make a geyser, we need to have superheated water, which simply means water that is boiling at higher than the normal boiling point. You can see on the diagram, increasing the pressure–moving up on the diagram from the normal boiling point–means that water stays in a liquid state until a higher temperature. Bingo! I think we just found out how geysers work!

 

Boiling

There is one more piece of the puzzle: How do we increase the pressure? By capping the boiling vessel, we don’t allow the air out. Capping the flask doesn’t instantly increase the pressure. Instead, as the water boils at the original pressure, liquid water turns into water vapor, which takes up about 1500 times as much space as in ts normal form. To fit in the fixed volume available to it (thanks to the cap) it has to become more tightly packed, which increases the boiling point slightly. This process repeats, causing the pressure to continue to rise and pushing the boiling point higher and higher!

As soon as the flask is open to the air again, we get our hydrothermal explosion: all of the compressed water vapor expands to its normal size flinging the surrounding water into the air, and water above the boiling point follows suit!

Water geyser 2

Three Things You Should Know About Telescopes

1) They Come in Three Flavors

ChromaticAberration

Image credit: Dale Mahalko.

All telescopes fall into one of three categories: refracting, reflecting, or combination. Most modern telescopes favor the reflector method for practical reasons. It’s easier to create and transport a large, precise parabolic mirror than a lens of equal usefulness. Mirrors also eliminate the problem of chromatic aberration (shown above; notice the discolored edges on the small boxes and the arm of the glasses). Chromatic aberration is an optical distortion resulting from light of different wavelengths emerging from a glass lens at varying angles.

2) Magnification Isn’t the Point

Neptune

Image credit: NASA/JPL.

At least, it’s not the only one. If a telescope zoomed in on the image your eye records of, say, Jupiter, you’d see a large, fuzzy blob. Light collection in the human eye is limited by aperture size and perceptual frame rate. Poor light-capturing ability translates to blurry views of distant, seemingly tiny objects. Magnification is nice, so the small eyepiece lens on a telescope does enlarge the final image, but the scope’s large primary lens or mirror serves a different purpose: gathering lots and lots of photons. The image above shows Neptune as observed by the Hubble Space Telescope, whose primary mirror measures eight feet in diameter!

3) You Can Build A Simple Model Out of Stuff You (Probably) Already Have

The quality will be far from professional, but this DIY project is a fun, easy way to explore the concepts at work in a reflecting telescope. Set up a curved shaving/cosmetic mirror opposite the light source you want to observe (try a flashlight, or the moon if you’re feeling crafty…NEVER THE SUN). This is your primary mirror. Place a flat mirror in between the primary mirror and light source, facing the primary mirror– that’s your secondary mirror. Position yourself behind the primary mirror so you can see its reflection in the secondary. Play with each mirror’s angle and distance to resolve your target image. How does it turn out? What are the limitations of the system?

Take this project further by experimenting with mirror & lens combinations (try a magnifying glass lens), measuring mirror and lens focal lengths, and/or mounting your optical components along a cardboard tube or other support structure. Again, do not use these methods to image the sun. Irreversible injury and/or fire may result.

For a higher-quality alternative, try the Galileoscope, a user-friendly refracting telescope designed for educators and curious people. It’s easy to assemble without tools or glue. Watch below as our Galileoscope goes from a pile of parts to a working instrument (also not safe for sun-gazing).

TelescopeAssemblyGif

Written By: Caela Barry

Curveball Science

The Magnus effect allows pitchers to throw curveballs, soccer players to bend kicks around defenders, and golfers to launch drives along near-triangular flight paths. This fun physics phenomenon relies on the difference in relative airspeed at various points on the surface of a round object.

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Viral video captures the Magnus effect in action, 2015. Credit: YouTube channel How Ridiculous. Full footage: https://www.youtube.com/watch?v=QtP_bh2lMXc.

Picture a ball moving through the air while spinning. For the ball to experience a net force, its axis of rotation must be oriented so that some points on the ball’s surface move in the same direction as its trajectory (let’s name one of these points A) while some move the other way (we’ll call an example of this type B).

MagnusDiagram

At point A, the air dragged along by the ball’s surface and the air farther away rush past each other in opposite directions; at point B, they move in the same direction, although one still moves relative to the other (unless rotational speed and flying speed are perfectly matched). This is a bit like the difference between two cars going in opposite directions on the highway and a car in the fast lane passing one in the slow lane.

Like a boat traveling through water, the ball leaves a wake behind as it cuts through the air. The differences between relative airspeeds around a rotating ball cause its wake to pull to one side, resulting in an asymmetrical imbalance of air pressure. This lopsided push bends the ball’s path as it travels.

MagnusGif

A DIY-friendly demonstration of the Magnus effect. Unlike the basketball, which had a backspin as it fell down the dam, the paper roll’s front edge is spinning along with its trajectory. This results in a backwards arc.

The Magnus force affects cylindrical objects in a similar way. Try this at home with a sheet of paper, rolled up and taped into a cylinder. Allow the paper tube to roll off the edge of an angled surface to give it a uniform spin, and watch its path curve!

Written By: Caela Barry

Fire Tornado!

Tornadoes are born when extreme weather circumstances come together. Their short, destructive lives are still not fully understood, but one leading theory goes like this: sometimes, winds at different altitudes blow at different speeds, rolling the air between them into a horizontal, rotating cylinder. If a supercell thunderstorm is nearby, the spinning column can be pulled into the maelstrom. Once the tornado is vertical, its lower end has the potential to touch down and wreak havoc on Earth’s surface.

West Texas wildfire

West Texas wildfire. Image credit: Texas Forest Service.

In a real supercell, swirling updrafts are created by variations in temperature, pressure, and wind speed in the storm area. In this experiment, we simulate updraft conditions by physically pushing the air into a rotating column formation using a window screen rolled into an open-ended cylinder. Without the screen (and the wind it generates), the spinning fire doesn’t do anything especially interesting. That’s because of Bernoulli’s principle: the faster a volume of fluid moves, the more neighboring molecules are sucked into the breeze. By giving the air a push, we draw extra oxygen in towards the flame.

FireTornadoGif

Fire tornadoes are spectacular in the lab, but you don’t want to see one in nature. These twisting ropes of flame have played a tragic role in several of the greatest conflagrations in human history. From Chicago to Peshtigo to Tokyo and beyond, they’ve spread blazes with devastating speed and blocked victims from reaching safety in nearby bodies of water.

At least one team of researchers is working towards harnessing the power of the fire whirl for practical purposes. Hot, clean-burning blue fire tornadoes show potential as a tool for improved oil spill cleanup.

As with any experiment involving combustion, check in with an adult, keep a fire extinguisher on hand, and exercise caution if you decide to make a flaming tornado at home. We used a turntable with a heat-safe covering, a non-flammable window screen stapled into a cylinder, duct tape, a glass flask, and a few ounces of 99% isopropyl alcohol to create our fire whirl.

Written By: Caela Barry

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

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