CoolStuff Newsletter Article                                                            Vol. 29, December 2007

Toying around with Science

If you’re like me, toys play an important role in your science teaching. Toys are readily available, are often inexpensive, and most importantly, illustrate physical principles in an engaging way. Toys not only spark interest but make scientific principles accessible and understandable to students of almost any age. Toys may often be used in lieu of standard laboratory apparatus. Doing so allows students to see, in a hands-on, mind-on fashion, how science extends beyond the classroom into their everyday lives.

The power and applicability of toys cannot be understated for they may be used to introduce a topic, develop concepts qualitatively or quantitatively, and assess student understanding. It’s as if toys were created for the inquiry-based classroom.

The toys discussed in this issue of CoolStuff represent only the tip of the iceberg. Science teachers tend to see the science in virtually every toy they encounter. The beauty of using toys to teach is that your students will start to see the science in everything!

~Chris Chiaverina

Nippon Airliner Struck by Lightning
Dramatic Electrostatic demonstration

Up, Up and Away!

One of the first science toys I ever owned was a water rocket. Essentially a plastic container with fins, the rocket is prepared for flight by partially filling it with water and pressurized air. When released, the rocket’s contents exit a small hole at the base of the rocket in one direction, pushing the rocket ahead with amazing speed in the opposite direction. A case of action-reaction, pure and simple.

I loved that rocket, but wished it would have gone higher. To address my need for altitude, I decided to build a missile that would be propelled by solid fuel. My friend Harry McKnight and I sent away for plans that we saw advertised in the classifieds in Science and Mechanics. The finished product, which took many weeks to complete, is seen, along with the two budding scientists, in the circa 1958 photo right. We were warned that our rocket was in essence a pipe bomb. That turned out to be the case, for after ignition and subsequent explosion, nothing of the rocket could be found. Undaunted, we constructed a second rocket.

I am convinced that the success of the second missile launched my career in science. The plume of fire and smoke exiting that rocket had to be seen to be believed! It was truly breathtaking!

Luckily, these days you and your students need not build dangerous solid fuel rockets if you are seeking great performance. With not much more than a plastic soda bottle and some cardboard you can construct a rocket capable of attainting truly amazing heights. Plans for single and even multi-stage rockets propelled by water and compressed air may be found on the Internet (see Interesting Links). Bottle rockets are also available commercially. Both single and two-stage systems will allow your students to investigate the effect of shape, thrust and multi-staging have on performance. These rockets are safe, easy to operate, may be used many times and attain amazing altitudes.

Get details on Bottle Rocket Launchers

New CoolStuff Video

A creative U.K. student has a unique take on Bottle Rocket launchers and some interesting insights on procedures. CLICK HERE 

Classic CoolStuff Video

One of our favorite video clips shows a  TV game show episode from Japan as they launch a man using Bottle Rockets. CLICK HERE

Green Science

On Feb. 2, 2007, the United Nations scientific panel studying climate change declared that the evidence of a warming trend is "unequivocal," and that human activity has "very likely" been the driving force in that change over the last 50 years. Concern over climate change and diminishing natural resources has prompted renewed interest in alternative energy sources. Possible replacements for fossil fuels include solar, wind, geothermal, biomass, and hydrogen power.

Of these energy alternatives, many feel that hydrogen may one day supply virtually every end-use energy need in the economy, including transportation, central and distributed electric power, portable power, and combined heat and power for buildings and industrial processes. High in energy content, hydrogen produces virtually no pollution when burned. In fact, when hydrogen is combined with oxygen, only water and heat are produced.

It is envisioned that hydrogen powered devices called fuel cells will allow the pollution-free production of electrical energy that may be used to power a car or even light your home. While this wide use of hydrogen is many years off, hydrogen fuel cell vehicles (FCVs) are currently in the pre-production stage of development.

Get details on the H-Racer Fuel Cell Car 

...other Green Stuff!

If you’re looking for a more down to earth way of demonstrating environmental responsibility to your science students, you may wish to have them monitor energy usage in their homes. Cutting unnecessary energy consumption in and around the home is one way every individual can make a difference.

The Watts Up? Meter makes it easy for students to see how much electrical energy is used by their appliances – coffee makers, light bulbs, televisions, refrigerators, etc - and how much it costs to operate them. Based on this information, they can devise a plan to promote energy conservation within their homes.

Get details on the new Watt's Up Meters 

Did you know...

Electric Cars have been around quite a while. So why are we still waiting...

France and Great Britain were the first nations to support the widespread development of electric vehicles in the late 1800s. In 1899, a Belgian built electric racing car called "La Jamais Contente" set a world record for land speed - 68 mph - designed by Camille Jénatzy.

It was not until 1895 that Americans began to devote attention to electric vehicles after an electric tricycle was built by A. L. Ryker and William Morrison built a six-passenger wagon both in 1891. Many innovations followed and interest in motor vehicles increased greatly in the late 1890s and early 1900s.

For more information visit: Speed Ace

A Question of Balance

Over three hundred years ago, Galileo realized that objects will continue doing what they are already doing. That is, an object at rest will remain at rest, or an object already in motion will remain moving in a straight line at constant speed. That’s provided that there are no unbalanced, outside forces acting on the object in question. This is Galileo’s Law of Inertia.

When no net, i.e. unbalanced, force or torque is acting on an object, the object is said to be in a state of equilibrium. According to the Law of Inertia, an object in equilibrium may either be stationary or moving with a constant speed in a straight line. As with virtually all physical science topics, toys offer a unique and effective way of presenting equilibrium and the Law of Inertia.

Take the amazing Levitating Globe for instance. Suspended in mid-air, the 4” globe seemingly defies gravity - inspiring wonder and stimulating thought. What keeps the globe hovering, motionless in space? Many students will suggest magnetic repulsion. If they do, they will be partially correct.

Get details on the Levitating Globe

Challenge students to suspend one permanent magnet above another. They will not be able to achieve equilibrium, not because of lack of dexterity but because it is physically impossible. The Levitating Globe achieves equilibrium through the ingenious use of a feedback mechanism that constantly adjusts the magnetic field produced by an electromagnet located in the base. If the globe starts to move downward, the field is automatically strengthened. When the field grows too strong, current in the electromagnet is reduced and equilibrium is once again restored.

Get details on the Balancing Bird

A beautiful, lower tech example of both translational and rotational equilibrium is the Balancing Bird. Like the Levitating Globe it hovers in space, but this time with a visible means of support. Well-placed masses in the bird’s wings and beak place the center of mass directly over the supporting pedestal. The bird remains perched on any support –its stand, a finger, a nose – even when a slight tap sets the bird bobbing or spinning.

The Constant Velocity Car beautifully illustrates dynamic equilibrium. Students can hear the car’s battery-powered electric motor yet notice that the car moves at a constant velocity. They may ask, “why is the car not picking up speed?” The answer: the balance between the forward propelling force created by the motor and opposing force of friction. Working in concert, dynamic equilibrium and The Law of Inertia insure straight line motion at constant speed.

Get details on the Constant Velocity Car

Electromagnetic Marvels

Have you been searching for a way to make the principles of electromagnetism transparent to your students? You need look no further than the Dynamo Hand-Powered Flashlight. Encased in a clear plastic shell are a disk magnet and two coils of wire. When you squeeze a handle, a ratchet and gear system sets the magnet spinning between the coils and, presto, the flashlight’s bulb lights up!

The Dynamo Hand-Powered Flashlight’s operation is based on Michael Faraday’s Law of Induction. Faraday’s Law states that the induced electromotive force, roughly speaking, the voltage, in a closed loop is directly proportional to the time rate of change of magnetic field through the loop. In other words, moving a conductor through a magnetic field produces a voltage in that conductor. The greater the relative motion between conductor and magnet, the greater the voltage, and in this case, the brighter the bulb.

Like the Levitating Globe (see above), magnetic repulsion is responsible for the operation two other marvelous toys, the Strobe Revolution and the Omega Levitron. Both devices demonstrate how opposing permanent magnets can produce levitation. However, like many physical phenomena, it’s not quite that simple. In both devices stable equilibrium is attained by means beyond magnetic repulsion, for as it turns out, no static arrangement of permanent magnets can be stable, alone or under gravity.

The Strobe Revolution’s stability is maintained by fixed stop that exerts a force on one end of the rotating axel. The Levitron’s top achieves stability through its spinning. As well as providing a supporting force on the top, the magnetic field of the base gives a torque tending to turn its axis of spin. If the top were not spinning, this magnetic torque would turn it over. Furthermore, a slight variation in the field of the base gives the top an inward nudge when it starts to stray from the center of the base.

The beauty of toys is that they often can be used to teach more than one scientific principle. This is certainly the case with the Strobe Revolution and the Omega Levitron. Each cogently illustrates the Law of Inertia: a substantial reduction in friction allows objects to maintain their motion for a long period of time. The spinning of both the Revolution and Levitron seems like it will go on forever. Blinking LED’s in the Strobe Revolution offer spectacular patterns and reverse-rotation illusions, both illustrating stroboscopic effects and persistence of vision.

Make your own Levitating Revolution

See the link below to Arvind Gupta's web site. Gupta is a strong advocate of teaching science with toys in India. His instructions for making a levitating pencil with ring magnets and a piece of a CD is a perfect activity for an introduction to magnetism.

Interesting Links: 

Next time... Supermarket Science

Sitting on the shelves of your local food store are scores of items just waiting to be used in your science classroom. Join us next time when we'll take a stroll down the aisles of a supermarket and do some serious shopping in the name of science.

Chris Chiaverina

About the Author

CoolStuff is written by Chris Chiaverina, past president of the American Association of Physics Teachers (AAPT) , award winning science teacher and author. Chris' passion and creativity in science education has made him one of the leading authorities in the United States on how to engage our students and inspire the same passion in them. Retired from New Trier High School's physics department, Chris is still active educating tomorrows' science teachers around the country, writing for the AAPT publication "The Physics Teacher", and has been keynote speaker for noted science organizations around the world.

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