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Household Physics for Fun and Entertainment (Hands-on Physics in a Virtual World)

Elwood Schapansky, PhD

I attended Colorado State University, from 1968 to 1972, on a National Science Foundation Science Faculty Fellowship. I was a Physics instructor at Santa Barbara City College, with a Master’s Degree, and NSF was providing funds to improve the level of teacher knowledge in the Community College System. Although not a requirement of the grant, I attained my PhD in 1972 and returned to teaching in Santa Barbara. I have often been asked to make science presentations in the local elementary schools and soon found that working with fourth, fifth and sixth graders suited me best. These students were invariably inquisitive, intelligent and willing to participate easily. I went to classrooms several times a year and one year held a five session class where nearby students walked to my laboratory to participate in a more extensive experience. It was wonderful for me, the teachers and the students. Years later I had some to these students in my college classes, and the early class had been a deciding influence to study science. As a teacher, I found this teaching rewarding and meaningful. Nobody failed and everyone learned something. In 1975 I began to pursue another passion. I started commercial flying, during the summer school break, in the bush near Galena, Alaska. This was fulfilling to me and allowed me to have a unique, refreshing cultural experience away from the classroom. Meeting and working with Alaskan natives was exciting, educational and meaningful. I still have lifelong friends from this period. On several occasions I presented physics to elementary schools in the bush. Native children have a completely different cultural outlook, but science is universal and they happily participated in the science lessons. Since I had no demonstration apparatus, I used what was at hand. Torches, cans, hoses, hammers and wheels became lab demonstration items. It was great fun. The experience in the Bush has influenced my thinking about presenting science to youngsters. I find I do not need a physics laboratory to present exciting and wonderful ideas. I just need the world around me, to provide

the apparatus to explain concepts and principles. Since I am no longer at the college, I use only my workshop as the source of demonstrations. It works wonderfully since almost everything I use is already familiar to the students. I now live half the year in Talkeetna, Alaska, which is on the road system, and do presentations at the local elementary school. Here again, even though I could borrow more sophisticated apparatus, I choose to use my workshop as the demonstration source. One of the highest compliments I have received as a teacher was from a class that begged me to continue teaching through their recess period. The class was captivated.

Teaching Physics at the elementary school in Talkeetna, AK Talkeetna is a small community with an eclectic citizenry. Many parents choose to home school their children, and most do an excellent job of it. It is hugely time consuming to do this, but many do it with pleasure and success. Since my goal in the elementary schools was to teach both the students and their teachers, I began thinking about what the home-schooled students were missing. I personally see great value in the public school system and promote it and assist it when I can. However, I could see a large group of children and parents who were missing science instruction from a trained teacher and scientist. I decided I would attempt to present to all the community, not just those in the public school. This seemed appropriate since years ago physics demonstrations were used as

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parlor entertainment and numerous new ideas were presented to lay people in their homes. Talkeetna has a very active non-profit Community Arts Program and a wonderful, intimate theater. It seemed the perfect place to try my idea of a community physics show. It was readily accepted by the leadership and promoted widely in the local area. An announcement made by the staff was particularly colorful and helpful.

Announcing the Physics Show

The local newspaper was extremely supportive of my efforts and gave me and embarrassingly large amount of publicity. The editor interviewed me and also attended the show with a plan of reporting on it. The news article is presented below. It was titled:

“Household Physics for fun and entertainment” Dr. Elwood Schapansky, retired professor of physics from Santa Barbara City College, and eight year Talkeetna resident, will present a show of basic physics in the Sheldon Community Arts Hangar, on Sept 4, 2009, at 7:00 PM. Dr. Schapansky has spent much time, during his retirement from teaching, promoting hands on experience in the sciences. He presents primarily to the teachers and students of the fourth, fifth and sixth grades. The presentation at the Sheldon Theater is something new, and is a throwback to years ago when science was a parlor activity for fun,

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education and entertainment. This show is an experiment to see if others share his desire to balance the move toward virtual experiences that are now the craze. His teaching experiences in college level physics labs have shown that students no longer have the confidence, dexterity and skill to do hands on experiments easily. It is his hope that parents will make more of an effort to provide manual activities and basic science education to their children. The Friday show will be based entirely on demonstration items that he finds in his personal workshop. Torches, hammers, crowbars, bicycle wheels, batteries, wires, cameras, pulleys, cans, boards, homemade tops, and gyroscopes will be used. There may be a few surprises. This is a hands-on show, in a virtual world!

Bicycle wheels are just one of the many items that retired physics professor Dr. Elwood Schapansky will use for a “hands on show in a virtual world”.

The show took place as planned. It was attended by only a few children from the public elementary school, but had a large number of home schooled children, along with their parents. In addition the local high school physics teacher attended, along with his entire class of eight students. It made me feel so good to have them there.

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Home workshop items used as demonstration apparatus

The audience at the Physics Show

Because of the unusual nature of this show, and the apparatus used for demonstrations, I present here a brief outline of the presentation, along with partial explanations of the concepts explored. The presentation took about an hour and twenty minutes, with questions afterward. I hope this proves helpful to the reader. Below is my outline for the show.

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Handout presented to attendees:

Physics 4 Phun Physics for Fun with Elwood Schapansky – Schapansky@aol.com 

September 4, 2009 

 I.  Introduction to the show ‐ my first physics lesson at age eight II,  The ocean of air we live in ‐  Atoms, Air, and Air Pressure   1.   Creating a vacuum with boiling water   2.  Smashing a coke can with atmospheric pressure (very dramatic)   3.  Smashing a gallon can slowly, with atmospheric pressure   4.  Smashing a plastic bottle with a Food Saver   5.  Inverting a glass of water using a card to hold the water 

6.  Siphons and barometers 7.  Atoms have a fingerprint ‐ showing the color of sodium light (done with a burner) 

III.  Newton’s First Law:  Mass and Inertia 1.  Galileo and the inclined plane ‐ friction fools us 2.  Using a bicycle wheel, with vertical axis, to demonstrate rest and constant motion 3.  Dropping a resting coin into a glass using a broom 4.  Breaking a stick, resting between two paper loops, by striking sharply   5.  Breaking either top or bottom string attached to a mass 6.  Driving on a hammer head by striking the handle 

IV.  Newton’s Second Law:  Net force and acceleration ‐ moving faster and faster   1.  How do multiple forces add up to zero?  What does that mean? (Vector quantities)     2.  Using the rotation of the horizontal bicycle wheel to illustrate unbalanced force    3.  Weight and mass V.  Newton’s Third Law:  For every force in the universe there is an equal and opposite force   1.  What pushes on us when we walk?  What happens on ice?    2.  Weight.  What is the reaction force?  Can we be weightless on earth?   3.  Static and sliding friction as related to glacier landings ‐ Angle of repose VI.  Machines and the concept of work   1.  Pulling a nail by hand ‐ hammer and crowbar as machines 

2.  Mechanical advantage ‐ pulleys and ropes as machines VII.  Rotational Motion ‐ wheels, gyroscopes, propellers and precession   1.  Bicycle wheel ‐ torque, angular momentum and precession 

2.  Spinning Tops (made with the lathe in my workshop) ‐ fun toy and precession demonstrator 

VIII.  Static electricity ‐ Direct and Alternating current   1.  Static Electricity – where does it come from? 

2.  Direct Current ‐ circuit elements, short circuits and open circuits 3.  Alternating Current ‐ transformers and voltage control demonstrated by wood burning 

pencil, cooking a hot dog, and disposable cameras (which contain a capacitor)  

Brief explanations of some of my demonstrations and examples:  

I. My first physics lesson, short-circuiting a 6V battery. As a child I watched my father test car batteries by sliding a wire across the terminals and listening for the snap of a good battery. I tried it and did not slide the wire. The short circuit caused the wire to glow red and burned my hands badly. My first physics lesson. It made me want to know why.

Painful short-circuit, when I was eight

II. A tablespoon of water is boiled in a soda can to eliminate the air inside. It is then turned upside down into a pan of water, creating a good vacuum, so it implodes violently. This is exciting and great fun.

Imploding a soda can 7 

A common vacuum packer, with a vacuum attachment, can be connected to a plastic bottle to collapse it. A tight hole must be drilled in the cap.

A 3 x 5 card can be placed on top of a completely full glass of water and inverted without spilling the water. Atmospheric pressure holds the card against the glass.

A common plastic hose can be used to demonstrate the use of atmospheric pressure to siphon water from one tank to a lower one.

III. The concept of inertia is introduced by reproducing Galileo’s inclined plane argument. If a small component of gravity is equal and opposite to the force of friction, the sliding mass will continue moving indefinitely.

By using a bicycle wheel, mounted on a vertical axis, the inertia concept is easy to explain. A wheel with good bearings will rotate a very long time. You don’t have to imagine the very long inclined plane.

Striking a card, on a glass with a coin resting on it, shows inertia since the card will move away and the coin will drop into the glass.

A small stick, suspended by two paper loops, will break before the loops when struck smartly by another stick. Pushing slowly will tear the loops.

The mass for the string demonstration is in my left hand.

The horizontal bicycle wheel is on the rear table

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A large mass, suspended by a fragile string and having an identical string attached to the bottom can be used to demonstrate inertia. Pulling sharply breaks the lower string. Pulling slowly breaks the upper string.

A hammer handle can be driven into the hammer mass while the mass is free standing. The inertia of the hammer is sufficient to allow the wood to be driven into it. I used a pipe as a simulated hammer, and drew lines on the handle to show its motion.

IV. What pushes us when we walk? Demonstrate pushing on the earth, and having the earth push on you. Imagine what happens with no friction, like on ice, or skates.

V. Weight - what is it and what is the reaction force? Imagine being on a scale in a falling elevator. What does the scale read? We feel weightless, but our weight is accelerating us downward at the same rate as the elevator.

As a glacier pilot, I never stop the engine of my airplane until it has stopped sliding. Then I am assured it will remain stationary, since static friction is greater than sliding friction.

Here I use an inclined plane to show static friction to be greater than sliding

friction. One can also talk of the angle of repose of piles of sand or rock

VI. A student is asked to pull a nail from a board, by hand. When it cannot be done, the question is asked, what is needed? A machine is the 9 

answer. A hammer, or crowbar is provided and the nail is easily pulled. Levers and machines can be explained.

A crowbar is a useful machine for pulling nails

A tug-o-war is set up between two people, with one person pulling on the pulley, and the other on the free end of the rope, which is tied to a post at the other end. The mechanical advantage of two easily allows the person on the rope to win.

Here a pulley is used to create a machine with mechanical advantage two.

The post does half the pulling for the student on the right.

VII. A spinning bicycle wheel is used to show angular momentum and gyroscopic procession. This is related to the precession of airplane

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propellers and tops, and is also why so many good pilots have trouble flying a tail-dragger airplane – the type of airplane commonly used in bush-Alaska.

Gyroscopic precession of a spinning bicycle wheel

I make tops on my home lathe, and make one model that is suspended by a string, on a bearing, on the top of the top. When released horizontally, the spinning top precesses, just like the bicycle wheel. I picked this idea up while in Russia, where it was used as a toy.

A standard spinning top, above, and the top with the bearing which allows it to spin horizontally, and precess

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The top spinning on a horizontal axis and precessing

VIII. Static electricity - demonstrated with bits of paper, comb and fur.

DC circuits - demonstrated by shorting a battery with a small copper wire, vaporizing it, and showing the need for a resistor in the circuit. Then a bulb was placed in the circuit, which lit normally. An open circuit was shown by removing the wire from one terminal of the battery.

It was explained that transformers require a changing current to operate, and thus we in the United States chose AC for our power-distribution. A step-down transformer was used to heat a homemade wood burning tool.

A step-down transformer, on the left, and an autotransformer were used to provide a controllable

low voltage to the home-made wood burning pencil, shown top left.

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A pair of copper wires was connected to a 120V wall plug. The extreme danger of this was explained and then a hotdog was used to short-circuit the wires. The hotdog was cooked and then later eaten by a participant.

A hotdog was cooked by using it as a short circuit in a 120V circuit

Finally, the danger of disposable 35 mm cameras was explained. One was dismantled to show the circuit board, containing a capacitor, transformer, oscillator and rectifier. It was shown how a 1.5 V dry cell could be used to charge the capacitor to over 300 V. The capacitor was then short-circuited to show the dramatic spark and sound. This final demonstration is indeed impressive, but a lot of the physics could not be explained at this show.

A disposable camera provides wonderful science topics

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