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Let our children_go_back_to_the_tradition_and_values_of_israel[1] (1)


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Let our children_go_back_to_the_tradition_and_values_of_israel[1] (1)

  1. 1. Let Our Children Go back to the tradition and values of IsraelIntroduction: When it comes to education in Israel, there is a consensus that a real changeof concepts and of conducting the schools – is essential. Ive analyzed this issue according to the Theory of Constraints (-TOC) 1 andfound that the fundamental problem is: lack of challenges – which leads to boredomand loss of interest. The bored students do not usually see any connection between the learningmaterial taught to them and the life-skills they need, and so they act accordingly. One area that suffers the most from this situation is Bible studies and theJewish Heritage. The program suggested hereby, is a challenging one that combines theseareas with active experiences and experiments in Science.Background: Today, every learning subject/class is taught separately. The subjects are notlinked or connected in school. This way of conduct leads to preoccupation withuseless unnecessary details. The conclusion Ive come to – with the help of the book "Noise"2 – is that wemust "combine like terms", and "house" different subjects "under a single roof", as wesay in Hebrew. Thus, we minimize the noise made by insipid details. To this many supporting references can be found. For instance: In Humanities and related fields of knowledge, it is customary to gather detailsinto a story in order to raise and maintain interest in a topic. The best way to ignite interest, curiosity and then creativity is to actively takepart in experiencing that thing. Actively taking part in experiencing something results in fascination in it, andis the core of Chemistry, Physics, Biology and the related subjects. It was not for no reason that the people of Israel, standing in Mount Sinai said“na’aseh v’nishma” (= we will do and then understand).The programs principals: The program is based on the following principals: a) Approaching the topic by telling a captivating story/riddle/dilemma3. This is done by using modern language the children could relate to, and by1 The Theory of Constraints (TOC) is a management philosophy developed by Dr. Eliyahu M. Goldratt, author of"The Goal", "Its Not Luck", "Critical Chain" and more. In recent years TOC is very popular in the high-tech andbusiness worlds.2 Jacob Burak’s book Noise: The Profile of a Cultural Disorder deals with social behaviours. All rights reserved to Dr. Rami Kallir Ltd ©
  2. 2. addressing deep familiar feelings4 – fears, doubts, insecurities, etc. – when presenting the protagonists problem. Each lessons original story from the Bible /Gemara /other-ancient-source is attached for frequent references to be made during the lesson. b) Structured guidance is given to students as to using TOC thinking tools so that the find logical practical solutions to the problem, which they can then inflict onto their own day-to-day lives. c) Experiments and practical activities illustrate the logical solution, so at the end of a lesson – the concrete outcome is an actual product. d) The activities and experiments are very clear, structured and easy to understand, so that any student/teacher/parent/grandparent can do them with children, using tools and materials found in every household. e) The program will be activated by direct instructive guidance, using specially-suited kits and tools (-CDs, websites, etc.) to implement the information. f) The program will be activated in several versions: as an annual/semestrial program according to age groups and different topics and subjects in the Bible and in Jewish tradition; and as special days according to Jewish holy days.The programs concept The combination of science and Bible studies makes a unique program thatmerges, for the first time, humane aspects such as storytelling and theatrical actingalong side scientific experiments. The program empathizes developing various thinking styles such logical,critical and creative thinking. Practical experimenting allows a heterogenic group of students to pleasurablyengage in scientific issues that are usually perceived as complicated and hard tounderstand. Many of the programs topics fit the formal educations curriculum, and canenrich it with much-needed active, practical, fun experiences, that are currently absentform science classes. The program can be annual or semestrial.The programs goal 1. Exposing the students to the connections and links between different disciplinary fields of knowledge. 2. Developing and nurturing the childrens curiosity, creativity and the drive to discover.3 "The only way to understand the world, Magnus once said, is by telling a story. Science, Magnussaid, only brings knowledge about how things are working. Stories supply understanding. " – fromMarcel Mörings novel, In Babylon (Amsterdam: Meulenhoff, 1997) p.85.4 As claimed in Bruno Bettelheims book The Uses of Enchantment, published in 1976 . All rights reserved to Dr. Rami Kallir Ltd ©
  3. 3. Suggested topics5 1. Tohu va-Vohu – "…the earth was unformed and void" – the science of Chaos – uncertainty as to whats to come – no control of time – building a time-pendulum. 2. Ha-Mabul – "The Flood" – global warming – greenhouse affect – ecological holocaust. 3. Moshe Ba-Teiva – "Moses in the bulrushes ark" – building Moses ark – floating on water – water proof materials and the surface tension of water. 4. Ha-Sneh Ha-Boer – The "burning bush"– low temperatures burnable resins (– inflammable materials). 5. Mayim Min Ha-Sela – "water out of the rock" – identifying plants that testify to the existence of ground water – water percolation – wellsprings, siphons and wells. 6. Homot Yeriho Noflot – "and the wall fell down flat" – uses of energy of sound – frequencies that crash rocks – ultra sound. 7. David and Goliath – the cumbersome physique of a giant; why smooth round stones – the motion-energies of a sling. 8. Akeidas Yitzhak –Sacrificing Yitzhak – as sacrificing infants was common, Abrahams greatness is to rebel against this. 9. Yosef Be-Mitzrayim – Joseph in Egypt – agricultural economy – how to educate the people to properly keep and store their crops – making matzas. 10. Lag BaOmer – ridding of all inflammable things before the time of summer heat-waves. 11. Hanukkah – using pure clear olive oil because it contains a lot of water that decrease burning. 12. Esh Min Ha-Shamayim – "Fire from heaven" – lighting fire without human touch. 13. Yaacov lays down on stones – right distribution of body weight. 14. Ha-Keshet BeAnan – "And the bow shall be in the cloud" – features of light: blue sky, red sunset. 15. Israelites and Philistines – technological society: processing metals, using wheels, navigation and trade Vs. agricultural society. 16. David and Saul – different sounds affecting different moods: battle-cries to lullabies. 17. Damning water – presence of parasites and germs in water – removal of them with plant extracts, etc. 18. Producing wine, liquor, bread and cheese – the birth of technology. 19. Burning incense – repelling flying insects – ridding of lice with lavender oil and rosemary oil. 20. Roll the stone from the wells mouth – protecting waters quality against animals.Workshops according to the Jewish holy days5 The Biblical quotes are taken from the Mechon-Mamre translation of the Bible on the internet. All rights reserved to Dr. Rami Kallir Ltd ©
  4. 4. - Rosh ha-Shanah and Sukkot1. Honey-dipped apples – preparing sweets with seasonal fruits.2. Mathematics and Sukkah decorations – preparing unique decorations: Mobius rings, spirals and more.3. Hag ha-Asif – Time of Harvest – picking olives, oil retention, preserving olives.4. Come the rain and the bow in the cloud – the rainbow – mixing and separating colors, white light and the colors of the rainbow.- Channuka1. Dreidels and optical illusions: making special dreidels with different spinnig illusions, 2/3 dimentional, movement and color illusions.2. Kaleidoscope: flexible morrors duplicate the candle light numerous times; creating a kaleidoscope with a triple prism, to get a new colorful look on the world.3. Candles: why pure olive oil? – making colorful candles.4. Shadows and colors: Do different light sources effect shadows? – building a peeping box, and experimenting with different objects and sources of different colors.5. Glowing in the dark: activity in an invisible "ultra-violet" light with light- emitting materials and phosphoric-color materials.- Tu bi-Shvat and Family day1. Spices and medicinal plants: etheric oils in plants – reviewing ways to extract smells from plants and experiencing dissolving oil in different solvents. At the end – preparing spicy fragrant oil in a little bottle.2. Chemical garden: a spectacular garden of crystals in liquid. We will demonstrate dissolvability of different materials in different solutions, follow the differences between them, and each student will create his/her own chemical garden.3. Tastes and smells: how many tastes are there really? Four or four-hundred? By making different favored drinks: a blue lemon drink; green strawberry drink, etc.4. Gel bracelets: using an amazing matter that absorbs water rapidly, turning it into soft gel particals. At the end we make a spectacular gel bracelet.5. Pattern and models: between art and science – students make their own palm- pattern with special matter which solidifies in one minute. Pour calcium sulfate into it – and get a palm model of their hand.- Purim1. Balance: What laws of physics allow an acrobat to walk on a tight rope without falling? – The activity will revolve around balance and momentums.2. Making make-up: What conditions are necessary to produce make-up colors? – How to add oil-based-pigments to water-based-materials?3. Optical illusions: Creating optical illusion with a ball and an induction coil. We will check how our eye-brain connection can change the way we see things; and create optical illusions of non-existing movement.4. Periscope: How can the features of light be used to see beyond obstacles and opaque matters? Mirror games: building a special periscope that enables front, rear and side sights. All rights reserved to Dr. Rami Kallir Ltd ©
  5. 5. 5. Noises and Sounds: How does sound turn into movement and movement – into sound? – Features and qualities of sound: how does sound travel, how is it formed, and how is it received by our ear? – We will make rain-sticks, rattlers and more.6. Glupie: un-sticky glue – How can we take glue and turn it into a soft lump that is not sticky? A chemical experiment that fascinates everyone! Mixing colored-glue with a special kind of material that makes it viscous, and the result is a new, limber, nice-to-touch matter thats fun to play with!- Passover – Pesach1. The great Heat Waves: activities for days of great heat waves: Static Electricity balloons sticking to walls, "stand straight" hair, paper dolls, neon light turn on without an electric current flow, and more.2. How do detergents work: Get to know the unique qualities of soap, and make colorful fragrant cosmetic soap.3. The Smell of Spring: How to get odors form spices and perfume-plants – we will review different ways to do so, and make perfumed papers, fragrant drinks and spice-oiled bottles.4. Big soap bubbles: making big soap bubbles takes more than mixing water and soap… other materials influence the bubbles flexibility and durability.- Lag baOmer / Yom haAtzmaut(=independence day)1. More than a Bow and Arrow: building and launching "rockets" with no flames involved. The rockets ascend several meters up.2. The Colors of Fire: fire contains all colors. The three primary colors – what happens when you mix them? Can you separate them back again? Breaking the white light into colors with the help of prisms.3. Iridescent Fire: at the end of the activity we have a water-oil colorful test tube illustrating the mixing and separation of colors.- Shavuot1. SAP (– special Absorption Polymer) turns liquid into gel: How can you turn a glass of water up-side-down and not spill a drop? – use an amazing water- absorbing matter that turns it into soft little "grains" of gel. The children get to know SAP while experimenting with it, and fill-up a test-tube with colorful gel-layers.2. Flying tray: how can we transfer water from one place to another without spilling it? – The wonders of the centrifugal force.3. Siphons and Archimedes cup: how the Greek ancient wise man prevented wasting expensive drinks and spilling them on the floor.4. Milk and its products: Making cheese out of pasteurized milk by adding a few drops of lemon juice to it. Moses in the Nile – Floats or Sinks All rights reserved to Dr. Rami Kallir Ltd ©
  6. 6. Equipment:Each kit contains:5 bowls, 5 bags with different materials for buoyancy (=floatability) test:stones, pieces of Styrofoam, pieces of wood, glass marbles, pieces ofplasticine, corks, iron nails, pieces of aluminum, pieces of cloth, sponges,pieces of papyrus plant; wax candles, papers, a small carton model of a boat, alittle doll.Goals:Get to know the features determining the buoyancy(=floatability) of an object.Terms:light, heavy, floats, sinks.Theoretical Background:When referring to the features and qualities of materials one often comesacross expressions such as "Aluminum is a light metal" or "Carbon Dioxide(=CO2) is a heavy gas". To compare heaviness or lightness between twomaterials, we must make sure other variants such as volume, temperature andpressure are equal.The ratio of Mass under prescribed conditions of temperature and pressure iscalled "specific gravity" or "density".Density is a measure of how much mass is contained in a given unit volume(density = mass/volume).In a given cubic volume a small amount of particles indicates low density, anda big amount of particles means high density.Examples for the density of several materials: material density Air 0.00129 Water 1 Iron 7.8 Aluminum 2.7 Alcohol 0.79 Ice 0.93 Honey 1.35 Olive Oil 0.9 Since the density of water is 1 (gram/cc) it is customary to comparedensity of materials to that of water. The density – also referred to as "specificgravity" or "specific weight" – indicates an objects ability to float. When an objects specific weight is lower than that of the liquid it is in– the object will float; when its specific weight is higher than the liquids –object will sink; when it is equal – object will hover in the liquid. Theres often an erroneous premise that the floatability of matters isaffected by their state (- gas/liquid/solid) or their viscosity. For instance, aliquid such as oil – which has a specific gravity lower than waters – will float All rights reserved to Dr. Rami Kallir Ltd ©
  7. 7. on it. Solid wax will also float on water, for the specific gravity of solid wax is lower than that of water. When an object consists of several different materials, its specific gravity (= density) is determined by its total weight divided by its volume. An object filled with air will have density lower than one, and will float on water. That is why ships can float on water. Iron and other heavy metals form their structure, but their volume is big and filled with air. Scientific thinking with the TOC thinking tools: Moses in the Box in the Nile Many years ago, the people of Israel resided in Egypt. Many days theywere living in a foreign land, and one day an Egyptian king was crowned, and heenslaved them. In-spite of the hard work, the Israelites numbers increasedconsistently. King Pharaoh searched for a way to decrease their numbers, and so heordered to throw into the Nile every Israelite born son. One of the Israelites was Amram, who had a wife – Yocheved, a son –Aharon, and a daughter – Miriam. Yocheved gave birth to another son, but could not bring herself to killing himas the kings order demanded. She hid her baby-boy in the house for 3 months, till itwas too difficult to keep doing so. Lets look at Yocheveds conflict from through the TOC conflict-clouddiagram: Obey order (=throw Protect the rest of baby in the Nile) the family Protect the whole family Disobey order (= Protect the baby hide baby at home) The way to evaporate this conflict cloud: she decides to stop hiding the baby,but not to throw him in the Nile as he is, but place him in a woven box. "And when she could not longer hide him, she took for him an ark of papyrus,and daubed it with slime and with pitch; and she put the child therein, and laid it inthe flags by the rivers brink." (Exodus, 2, 3). She weaves a box of papyrus. Papyrus is a water plant with upright stems. Thestems contain air, and therefore float on water. Papyrus was accessible since itnaturally grows on river banks. Another advantage of this plant is that its a flexible material and so a boxmade of it, should it come upon a rock or a branch – it wont break, but merely fold. Asimilar box made of wood – might break. All rights reserved to Dr. Rami Kallir Ltd ©
  8. 8. The disadvantages are: the box is not totally sealed. It is a sort of a woven basket, into which water can enter and wet the baby. Moreover, after a while the papyrus absorbs the water, and the box could sink. Yocheved is aware of the advantages and disadvantages of her material of choice. She solves the first problem by coating the inside of the box with clay, that fills-up gaps and empty spaces, and prevents water from penetrating and wetting the baby. She also covers the outside of the box with pitch, which is an oily substance that prevents water form being absorbed by the papyrus. Yocheved puts her son in the box, and the box in the river. She appoints his sister Miriam to be his sentry and be on the lookout for him. The baby floats down the river and reaches Pharaohs daughters bathing area. Pharaohs daughter takes pity on the infant, and decides to adopt him and rase him as her own. She names the baby "Moses". His sister, Miriam, suggests the adopting princess to take a wet nurse from the Israelites to breast feed him – who is non other than Yocheved – and by that the baby is actually returned to his original family for a while. Later on he goes back to being brought-up in the kings court. Now, lets take another look at Yocheved making the box with the TOC tool called "the Ambitious Target" (AT). AT: Saving the Baby Obstacles Intermediate ObjectivesIf put in the river – baby will drown for it cannot Make baby float by putting him infloat nor swim a box made of something lighter .than water Use accessible available material.Materials to make the box are hard to come by .that doesnt cost anythingBox can hit a rock or branch and break .Use flexible materialA papyrus box is like a basket which allows .Fill-up empty spaces with clay.water entrance so the baby would get wetWater will be absorbed by the box and itll sink Cover the outside of the box with .water-proof matterBaby cannot survive for iternity in the box Place the box in the river so itll .sail to a safe placeUnexpected things may happen Let his sister be on the lookout for .him The next experiments will demonstrate the different density of different objects, which is reflected by the objects buoyancy. We will try to change the specific gravity of the objects, and by that to influence their buoyancy. We will examine that by experimenting on different objects, the human body, and by changing a dolls center of gravity. All rights reserved to Dr. Rami Kallir Ltd ©
  9. 9. Experiment number 1: floats or sinks Goal: Estimating objects buoyancy and then testing it. Equipment (– for a party of 4 students): a bowl, a bag containing: stones,straw, pieces of paper, pieces of Styrofoam, pieces of wood, glass marbles, Plasticine,corks, iron nails, pieces of aluminum. Procedure: 1. Students take a close look at the materials, and speculate which will float and which will sink in water. 2. A table such as this may assist students to organize information: Name of object / Materials Speculation: will object float Result: did object object is made of ?or sink in water ?float or sink 3. Fill bowl up with water. 4. Place the objects in the water, and check whether the results mach the speculations, and add result data to table. What happens and why: Materials containing air, such as Styrofoam, corks and wood, have low density, so they will float on water. Materials like glass, metal, stones, that have high density – will sink. Materials such as paper, sponges, etc., also contain air, but water will penetrate fairly easily, replace the air, and make them sink. Experiment number 2: floats but sinks Goal: Increasing an objects specific gravity so that it would sink. Equipment: same as in experiment No.1 . Procedure: 1. Ask students to take objects that floated, and make them sink. 2. Examine the different techniques students used in order to sink objects. What happens and why: Possible examples: attaching Plasticine to wood or Styrofoam, inserting nails in corks. If we take an object with density lower that that of water, and attach to it an object more dense than water, we will get a new object, with density depending on the materials creating it. If the specific gravity of the new object is lower than that of water – itll float. If it is higher – itll sink. Using that enables us to sink floating materials. In experiment No.2 we saw that some objects contain air, and therefore float. But when water replaces the air, the specific weight increases, and the objects sink. All rights reserved to Dr. Rami Kallir Ltd ©
  10. 10. Experiment number 3: sinks but floats Goal: Decreasing an objects specific gravity so that it would float. Equipment: same as in experiment No.1 . Procedure: 1. Ask students to take objects that sank, and make them float. 2. Examine the techniques used by students to make objects float. What happens and why: Possible examples: sealing both ends of plastic straw, so air is caught inside; attaching Styrofoam to an object that sank; flatten Plasicine and shape it like a little boat. As in the prior experiment we created a new object out of several materials and air. If the new objects specific weight is lower that that of water – object will float; if its specific weight is higher – itll sink. Experiment number 4: applying wax to paper Goal: preventing water from saturating the paper. Equipment (for each student): pieces of paper, wax candles. Procedure: 1. Hand out pieces of paper and ask students whether one of the former techniques will be efficient for paper to float on water. 2. Hand out wax candles. Each student will rub wax over paper, creating a thin water-proof layer on both sides of the paper. 3. Place wax-covered paper and see if it sinks. What happens and why: In experiment No.1 we saw that the paper first floats, and then sinks. That was due to the papers fibers being saturated by water. Air went out and water in, so the paper sank. In order to make paper float, we must prevent water from penetrating. Covering paper with wax shuts the tiny holes in the paper, and prevents air form escaping and water form entering. Moreover, wax itself has low density (- as was demonstrated in Experiment No.1 when the candle floated). Experiment number 5: floating boat Goal: creating a boat that wont sink. Equipment (for each student): a carton board boat model + instructions, asmall doll, wax candle, Bristol board or wax paper. Procedure: 1. Rub wax candle over bottom and outside of boat model. 2. Assemble boat according to model-building-instructions. 3. Place doll in boat, and then – boat in water, and sail it. What happens and why: Boats and ships are usually made of materials that have higher density than that of the water they displace. In spite of that, they still float. The reason is their structure, which is essentially a hollow hull filled with air. The total density of the vessel is lower than 1 (– which is waters density), and so it floats on water. All rights reserved to Dr. Rami Kallir Ltd ©
  11. 11. David and GoliathBiblical Story: The Israelites stand timid and helpless against the Philistines. Thephilistines have several advantages, one of which is mastering the arts ofmetal-processing and of using horses and chariots. That meant the Israeliteswere inferior to the Philistines when it came to combat battling. Moreover, the philistines have Goliath – a fearsome powerful giantwith a shiny armor and vast military experience. "And there went out a champion from the camp of the Philistines,named Goliath, of Gath, whose height was six cubits and a span."(Saul A, 17, 4) And Saul said to David: Thou art not able to go against thisPhilistine to fight with him; for thou art but a youth, and he a man of warfrom his youth.(Saul A, 17, 33)David is facing a conflict: to-fight or not-to-fight Goliath. To Fight Goliath Win the battle Survive Not to Fight Avoid personal Goliath riskThe premises behind the dictums: a) Victory over Goliath will determine the wars fate. b) Avoiding personal confrontation with Goliath increases Davids chances of survival. c) David is very likely to loose to Goliath. Against the common opinion around him, David decides to acceptGoliaths challenge. King Saul gives him a sward and armor – the sameweapons as the ones used by the Philistines, but of inferior quality. David wants to fight in a way that would let him benefit from hisadvantages, and not this "modern" way in which Goliath has the upper hand.So, David dismisses the royal weapons, and chooses over it his shepherdssling and some round smooth river stones. So it wont be a head to head combat, but David will have the advantagesof speed and accuracy and of using the distance from Goliath. All rights reserved to Dr. Rami Kallir Ltd ©
  12. 12. Goliath looks down on David because he is so young and small, and also because of his weapon of choice – a sling is considered ineffective and inaccurate, and Goliath is well protected behind his armor. There only a single exposed spot – on his forehead – much like Achilles hill. The usage of stones and weapons is an ancient one. In the story of "Pilegesh Ba-Givaa" (– the mistress in the city of Givaa) some 700 men of the Binyamin tribe (tribe of king Sual) gathered. Alongside men of sword were a lot of stone throwers: "All this people, even seven hundred chosen men, were left-handed; every one could sling stones at a hair-breadth, and not miss." (Judges, 20, 16). It is very probable that other tribes had some skilled stone throwers as well. But still slings and stones were considered inefficient – see Yehuda Zivs interpretation about it. That leads us to believe that David had further knowledge of stone throwing, knowledge that gave him a significant advantage over Goliath. Davids challenge would be: fighting Goliath while avoiding personal risk, as best he can. "And David said unto Saul: I cannot go with these; for I have not tried them. And David put them off him. And he took his staff in his hand, and chose him five smooth stones out of the brook, and put them in the shepherds bag which he had, even in his scrip; and his sling was in his hand; and he drew near to the Philistine… …And it came to pass, when the Philistine arose, and came and drew nigh to meet David, that David hastened, and ran toward the army to meet the Philistine. And David put his hand in his bag, and took thence a stone, and slung it, and smote the Philistine in his forehead; and the stone sank into his forehead, and he fell upon his face to the earth. So David prevailed over the Philistine with a sling and with a stone, and smote the Philistine, and slew him; but there was no sword in the hand of David." (Saul A, 17,39-50). David has experience in using a sling and smooth round river stones, and heappreciates the virtue of their accurate move in the air. When a stone, any stone, is thrown, a number of forces are applied on it,causing it to move in several directions. The distance and accuracy that the stonereaches are the result of adjusted calculation of all forces applied on it. The initial velocity is derived form the force applied on the stone until itleaves the hand or the sling. The sling is used as a lever-arm to enhance the force. Other factors are the mass (-weight) of the stone, friction with air, earthsgravity, and moving around axis that decelerate and stop, and often divert forwardmovement. Davids knowledge became common knowledge, and the sling is also knownas "shepherds sling" or "Davids sling" and unfortunately a lot of our IDF soldiershave been hit and injured by stones shot from these slings. All rights reserved to Dr. Rami Kallir Ltd ©
  13. 13. Physical background: The movement of any body – excluding one of atomic sizes – abides byNewtons laws of physics. Specifically, by his second law: Force = mass * acceleration F=m*a . We will break down the movement of a thrown body into segments, anddetermine for each segment what the leading parameters are. For the sake ofsimplicity, let us look at a ball game thats being thrown. Segment A: the ball is at rest, so its initial velocity v0 = 0. The hand muscles apply force (=F) on the ball for a period of time (=t). theball leaves the hand at a speed of [vt] which is considered its final velocity, becausesince the time the ball has left the hand – no force is applied on it, and the ball will notaccelerate any more. The final velocity (vt) is, therefore, the multiplication of acceleration (a) bytime (t): vt = a * t . The lighter the body is, which means the smaller its mass is – the easier it isfor us to apply greater force on it. Be it that our force is limited, we can obviously only throw bodies that weighup to a certain weight. Segment B : the ball is flying in a certain orbit till it hits the ground or an obstacle. Fromthe moment the ball leaves the hand the throwing-force no longer affects it. Threeother forces do: 1) Gravity – a force that pulls the ball down, towards the ground causing the balls orbit to be an arched one. 2) Friction – the friction of the air causes deceleration. Deceleration is the opposite of acceleration. 3) Fluctuations - various fluctuations that move the ball round and side ways, at the expense of moving forward. Segment C: the Hitting Phase, which is rapid deceleration. Deceleration is actually negative-acceleration. So the formula remains thesame, only reversed directions: -F=m*(-a) . The heavier the body is, the greater the force is, and the harder it is to stop is. Activity number 1: the Effect of Mass and Shape on Movement To quickly throw objects of great mass, a lever is used. Our hand is a lever,but when it comes to hitting a ball – the baseball bat or golf club extends the lever-arm, enhancing the hitting force. Using a sling also extends the lever-arm as well as the time of acceleration, sothat the stone sets off at a greater speed than when it leaves a hand. The catapult is the device used in ancient times – till canons were invented –to shot massive stones at fortified cities. In this day and age of automatic weapons, rockets and missiles, at the verge oflaser and sound-wave based death rays, some do not think much of sling-shots, but itis important to keep in mind that wars are not just a recent phenomenon, and a stoneshot from a sling can cause death and severe injuries, much like a gunshot. All rights reserved to Dr. Rami Kallir Ltd ©
  14. 14. For the sake of safety, we will use only Plasticine or soft clay. Equipment: For the Catapult: Plasticine, doctors sticks (for throat culture, etc.) flat saucers, scotch-double-sided-tape A pencil or another straight thin stick to be used as a hinge, Open space to practice throwing, Targets – preferably ones that the Plasticine will stick to. Procedure: 1. Make a sling out of the stick and the saucer according to this diagram: 2. Put our little catapult on a pencil or such object for it to be the hinge of thelever-arm. 3. Place a little Plasticine ball on the saucer, and flick other end with yourfinger. The ball will "fly" in an arched orbit towards target. 4. It is possible to use one hand as the hinge, as the other hand flicks the stick.That way the force is greater, and the balls can fly horizontally. 5. Arrange a shooting practice range where students must shot into boxes or other targets. 6. Make balls different-sized balls: small, medium and large and check which one "flies" the furthest. 7. Make from similar sized balls different-shaped "bullets": ball, disc ,snake, pyramid and so on, and check how an objects surface affects its "flight". The more symmetric the shape is – less energy is lost to friction, and the better the object "flies". Activity number 2: Using a Sling to Shoot Plasticine Balls Equipment: Plasticine, 1 meter of wide-gift-wrapping band, Open space to practice throwing, Targets – preferably ones that the Plasticine will stick to. Procedure: All rights reserved to Dr. Rami Kallir Ltd ©
  15. 15. 1. On one end of the wrapping band, make a loop-hole wide enough for a wrist. 2. On the other side tie some knots, to ensure good hand-grip. 3. Fold wrapping-band symmetrically, so both sides are of equal length. 4. Insert wrist into loop-hole, and hold other band-end in that very hand. 5. Go out to the shooting range and aim for the targets. 6. Place the Plasticine ball in the middle of the band – where it is folded. 7. Turn the band holding the Plasticine ball faster and faster, until it seems to fly at the target youre aiming for, and then – open your hand, let the band go and the ball fly towards the target. 8. Repeat this activity till some sling-shooting skill is obtained. 9. We realize that the ball does not always fly as we intended, so we learn to appreciate David and the skilled biblical shepherds.Activity number 3: Following the Balls Move in the AirEquipment:For each student:A rubber ball(– or Plasticine to make balls from – that will shorten thethrowing distances, but will be a much more economic solution),Gift wrapping band,Scotch tape,Open space to practice throwing,Targets.Procedure:1. With the scotch tape, attach a gift-wrapping-band "tail" to every ball.2. Throw the ball in different angles: acute, obtuse and right angles.3. We notice that the more obtuse the angle is – the flatter the arch of the orbit is.4. A vertical throw has the longest time-span.5. "Catch the tail" game: First, students pair-up. Then, in each pair one student throws the ball while the other has to catch it by its "tail" (- wrapping band) as far from the "head" (-ball) as possible.Activity number 4: Energy Loss: How Shape Effects Throwing DistanceWhen a smooth, round symmetrical river-stone is thrown, itll turn around oneaxis, maintaining its turning direction, and its kinetic energy. When a common asymmetrical stone is thrown, itll turn around severalaxes, each time in a different direction, so the turning direction will differ, thekinetic energy will decrease, and the stone will soon drop, never reaching itstarget. All rights reserved to Dr. Rami Kallir Ltd ©
  16. 16. Equipment: For each student: Open space to practice throwing, Targets. Procedure: Now that we are aware of the significance of throwing angle, let us mark some distance-units and targets in our field/open space. Take some Plasticine, and shape the exact-same amount in different ways: ball, egg, disc, cone, etc. Each time shape the Plasticine, and throw it, aiming at the target, to see which shape reaches the farthest. The best way to conduct this experiment would be to re-throw similarly sized and shaped Plasticine lumps, and write down the results to get the average from. It will show that the ball, or – like the American footballs ball – egg shaped lumps go the longest distances. In the next experiments we will try to understand why the smooth, round symmetrical river-stone is more accurate than others. Activity number 5: Dreidels Goal: Getting to know the different factors affect a dreidels movement. Background: Why bicycle in motion does not fall is a question difficult toanswer for many students of physics… until they perform experiments withgyroscopes. In-fact, it all comes down to Newtons first law of motion, that states that"Every object persists in its state of rest or uniform motion in a straight line, unless itis compelled to change this state by forces impressed on it." It is easy to understand this when dealing with an object moving in a straightline: it takes force to move a rested object. It also takes force to divert a movingobject, and also to stop a moving object. This is the law of conservation of linear momentum. But for an objectrotating, the conserved momentum is that of the axis or plane of rotation. That explains why a dreidel will be leaning on its side when "standing" still,and will stand on end when spinning. And this demonstrates the law of conservation of angular momentum. The two forces impressed on the spinning dreidel are earths gravity verses themomentums conservation. Usually there are some disturbances due to energy loss or unequal weightdistribution. The verbal and mathematical explanations for the movement of a dreidel or agyroscope are not simple. We will try to overcome their complexity with severalexperiment in which we will deliberately make different changes and test each timehow those changes affect the dreidels circular motion. It is important to note that we have no means to measure the dreidels spinningspeed, so our test is one of quality. All rights reserved to Dr. Rami Kallir Ltd ©
  17. 17. Dreidels and Conservation Equipment: Carton disks with a hole in them Glass marbles and some insolating tape (- duck tape), Or: beads and half a skewer. Some crayons and stickers for decorating purposes Plasticine. Procedure: Preparing a Dreidel: Insert the glass marble into the disks hole, and cover one side of it with the duck tape, or Slide the half-a-skewer through the beads hole and place the carton disk on the bead so the skewer is facing down. To see what affects the motion of a dreidel, we will perform some changes,checking how each one of them affects the dreidels motion. Experiment 5/1: Friction Friction is created when two objects come in contact, and at least one of themis moving. Here, the objects are the dreidel and the surface on which it is turning. The fewer points of contact there are, the smaller the friction is, and the longerthe dreidel saves its kinetic energy, and therefore keep on spinning longer. How can we reduce friction? – The change can be made to the surface or tothe dreidel itself. a) Changing the surface: place the dreidel on a surface such as a smooth table, a floor, a sandy ground. Check which one makes the dreidel spin for the longest time. b) Changing the dreidel: the smaller the dreidels-surface-area touching the ground/surface is, the smaller the friction is. Since the marble/bead is round, it should have but one point of contact with the surface, causing minimal friction. Experiment 5/2: symmetry around spinning axis The weight distribution around the spinning axis must be equal, or else, thedreidel will quickly lose the energy given to it. Symmetry is changed by tilting thecarton disk, or by adding Plasticine on one side of the dreidel only. Experiment 5/3: weight distribution The heavier the weight at the discs periphery is, the longer the dreidel willspin. In the equation of linear motion, the momentum equals mass times velocity. In acircular motion, the circular momentum is set by the multiplication of the momentum– hence, lever-arm length times the weight – and the rotating speed. All rights reserved to Dr. Rami Kallir Ltd ©
  18. 18. The faster the spinning speed is, the bigger the circular momentum is. Thebigger the wheel is, the greater its stability is. The better the weight is distributed inthe periphery, the more stable the wheel is. A typical example for that are the bicycle wheels. Bigger wheels are morestable than smaller ones. The weight distribution is also very clear when looking atbicycle wheels – the weight is mostly in the periphery. It is advised to compare two dreidels of the same size, and 8 equal pieces ofPlasticine. On one of the dreidels add 4 pieces of Plasticine to its center, and on the other– add 4 pieces to its periphery area. In this sketch, the dreidel on the right is more stable than the one on the left. Activity number 6 –round smooth river stones (=r. s. river stones) vs. common stones Equipment Several round smooth river stones (=r.s.river stones) Several common stones Procedure Carefully choose several r.s.river stones and several common stones. Try andspin all stones for as long as possible. It will become clear that the r.s.river stones aremuch more capable of spinning; and that the more symmetric the stone is – the longerthe spinning will last. Note:Since symmetric r.s.river stones are hard to come by, we will use hard boiled eggs forthe next experiments. Boil an egg with some salt. The salt keeps its shell from cracking while itscooking. Experiment 6/1: Spinning a Hard Boiled Egg If we take a dreidel and try to make it stand on end, itll tip over onto its side. But if we spin it, itll stand on end for some time, even though it will bestanding on one single point. A hard boiled egg will do the same. If we try to make it stand on end still,balanced, itll roll over on its side. But if we spin it – itll rise up and stand on end. How does the spin make the egg stand on end? When an object rotates, it creates a physical effect called "angularmomentum". The angular momentum has a direction – the direction of the axis of thespin. The spinning object abides by the law of conservation of angular momentum;hence, for an object to change its state, a force must be impressed on it. All rights reserved to Dr. Rami Kallir Ltd ©
  19. 19. If we spin the hard boiled egg at great speed, we will see it raising-up,spinning standing on its end. The faster the egg spins, the greater the angularmomentum and the longer the egg will rotate standing on end. The spinning egg traces out a little circle. The more symmetrical the stone is,the smaller the circle. Several factors affect an objects symmetry; for instance, theinner weight distribution – every egg contains an air bubble that alters the eggs innerweight distribution. Experiment 6/2: Comparing Velocity and Spin Duration. The angular momentum is better kept, the more symmetrical the stone is.Since we have several eggs, we will spin them and measure the spin durations andnotice a slight yet significant change from egg to egg. Moreover, we shall crack oneof the eggs and take out a small piece of its shell. That eggs spin duration willimmediately change. And… a Story In addition, here is a story that was published in "Einayim" (= "Eyes")magazine. It was written by us and is related to the subject. A Competition of Weights: When we were children, we used to play outside. We had a "hit the target"game. We would pick an object such as a barrel or a big rock, and try to shoot stonesat it. At first, I wasnt very good at it. The stones I threw always landed too close,and I thought it was due to my poor aiming, or lack of strength. To improve my scores, I had collected some grovel stones and practice in ourback yard. One day my dad saw me throwing stones and hitting nothing. He looked at thelittle stones I was holding, and handed me one that was bigger. "Here, try this one," heoffered. I held his stone in my hand. It weighed a lot more than my stones. I thought Idhave to use a lot more power to throw that one. So I tried my best, and threw it as hard as I could. It landed very far. I had noidea I was that strong. I picked it up and aimed again. This time, I didnt try that hard.I concentrated, threw and hit it! I tried once more, and I struck again; and the next time. I concluded it had something to do with that stone being heavier than thegrovel stones. I found an even heavier stone. I held the heavy stone in my hand, concentrated, aimed, threw it… and itlanded so close to me, it nearly hit me. That day I searched for no explanations to it all. I jest kept on practicing withthe medium-weight stone. A few years later I learned in physics class about persistence and friction. Persistence is a quality that every body or object in the universe has. It meansthat the object will continue moving (or resting) in the same manner, unless weimpress on it a force that would move it otherwise. All rights reserved to Dr. Rami Kallir Ltd ©
  20. 20. Persistence is dependent on an objects mass. The lighter the object is – theeasier it is for us to move it; hence – the lower its persistence is. And vice versa: the heavier the object is – the higher the persistence. That explains why it was so difficult for me to throw the heavy stone. I had touse a lot of power to overcome that stones persistence. Friction is a force that exists between two objects that are in contact with eachother. If one of the objects is in motion, friction will slow that motion down. When a stone goes "flying" in the air, there is friction between that stone andthe molecules of the air. If the friction of the stone is high – the stone will moveslowly. The smallest stone was not heavy therefore its persistence was low. But aseasy as it is to throw it is to be stopped. Thats why I couldnt throw it very far. The medium weight stone is in between – its not too hard to throw, and notvery easily stopped. To try it for yourself you could make three balls of Plasticine: A small sized one – the size of a fingernail; A medium sized ball – the size of your thumb; A large ball – as big as your fist. Take a flexible plastic spoon to be used as a sling. Place one ball on the spoon and hold its handle in one hand. Carefully bendthe spoon with your other hand on the other end… and let that hand go. The ball will go flying in the air. Do the same with all three balls, using equal force. Check which of the three balls reached the farthest. All rights reserved to Dr. Rami Kallir Ltd ©