Physics Education for Young Generation Kiichiro Kagawa NPO: Fukui Science Education Academy JAPAN
The Aim of our NPO (FSEA ) • 1) Science workshop for young people • 2) Development of new experiment • 3) Cooperation with foreign countries Retired from Fukui Univ. in 2010, while NPO was founded in 2009
Regular private class for children (2009~2014), two times in a month, Sat. ９：３０～１２：００ 大気圧の実験（留学生が指導） 児童が自分の考えを述べている CD 分光器をつくっているところ 水を入れるとコインが浮かび上がってくる （竹ぐしは目の位置の基準にする） Our hope is to bring up excellent scientists and engineers
The most representative educational experiment we developed Frictionless equip. Artificial snow crystal Water lens microscope PATENT: No. 5257879 All these were published In J. Phys. Education (England)
Attitude towards Physics Education （１） Try to Separate from school textbooks （２） Try to use ordinary materials. Don’t use commercial kits, which degrade children’s ability. （３） Try to encourage to have logical thinking through experiments （４） Try to use beautiful phenomena as the topics of study (rainbow, snow crystal so on) （５） Try to encourage to repeat the experiment with careful observation (small discovery) Even physics education, there should be originality .
Chapter １ • Frictionless Demonstration Using Fine Plastic Beads for Teaching Mechanics Frictionless Demonstration Using Fine Plastic Spherical Beads for Teaching Mechanics
Introduction • Mechanics is most important to understand Physics system • However, only through training to solve calculation problem in high school Most unpopular subject in high school The reason 1) Due to the friction, we cannot demonstrate the law itself. 2) For falling objects, phenomena finish in a short time (less than 0.5 second). Student cannot see carefully with enough understanding
Commercial equipments for frictionless motion Car including slope ¥46.000 Car (1set): ¥21.000 Air slide track ¥210.000 (2000 US$)
Diameter is Microscopic view about ０．３ｍｍ of Plastic beads 1 ㎜ Work as ball bearing; beads are rotating Plastic beads Uniform linear motion Almost no energy loss because the mass is very small
Demonstration of the principle of this frictionless equipment for children The plate with doll move smoothly, The Ping-Pong balls are rotatin g.
Rainbow Experiment Using Fine Plastic Be ads Beads scattered on a black paper work, same as water droplet.
How to treat the beads Take out the breads after experiment using vacuum cleaner, or wipe with wet paper Scatter like shaking pepper . Almost invisible for our eye. But if you look at the surface from an oblique, it looks slightly white.
Book of Nuffield “O” level(1972), using metal iron ball bearing small ball(1~2mm) Heavy object: ~1kg Only horizontal surface, No application for slope
Published in Journal of Physics Education 2008
Ａｄｖａｎｔａｇｅｓ ｏｆ Ｂｅａｄｓ Method ・ Easily obtainable object of which bottom is flat (but should be light) ・ Very cheap( 80 US$ for 1 bottle (700g), one time only a few g) ・ Even slope, the beads can be attached by electrostatic force. (frictionless slope) ・ Systematic understanding is made because all experiments are done using the same object on the frictionless plate. .Students can touch the equipment by themselves as they like. Weak points: 1) In high humidity, friction increases 2) Too much density increases friction
Objects used for frictionless demonstration petridish lid Bottom plane should be flat and less 100g
Equipments for frictionless demonstration Size: 183 x 91 x 6 cm Weight: 7.5 kg (Using Styrofoam, but covered by 2mm Plastic plate) Flatness is impor tant 90 x 60 x2 cm, 7kg For group experiment (ordered to professional) We say, “ friction plate ”, “ beads plate ”
First Law of motion Strobe lighting; T=0.25s (Uniform linear motion, viewed from the top)
Pulse light source to record the track Diode light source(red or green) ; Off and on , Periodically flash Petri dish Repetition :5 Hz Recorded using a digital camera: 1sec
Circular Motion Using a String and Cylindrical pipe Plastic pin lid with a Projected shadow Bright light source hole string Using projected shadow, We can show that circular motion is Simple harmonic If there is quite no friction, the oscillation circular motion keeps going on like a planet motion.
Rotation of rigid body Center ter of of mass ss Center ter of of mass ss On the frictionless plate Usually, to have the image is difficult for students
Law of conservation of angular momentum( L = r x p ) Circular motion using string End of string was fixed so as to be coiled around the pole; ( with decreasing r , V increase )
Law of inertia Suspended weight Uniform motion Weight moves to frontward It stay there; no transmission of force Pull suddenly
F=ma( 運動の第二法則 ) High school textbook Using Wheel car For students, it is difficult to understand that this is a general low
Accelerated motion Demonstration of second law M LED, 10 Hz On bead plate Constant force pulsar Petri dish Weight: ２０ｇ Ｍ＝ 53. 53. ４ｇ V = △ X/ X/ △ T Ｍ＝ 153. 153. ４ｇ
Acceleration F=ma M (Second Law of Motion) We can change m and F, ビーズ板 independently. F: weight( ２０ｇ ) Constant force Ｆ＝ｍａ Under various mass 250 (48.8g) 200 平均の速度ｖ [ｃｍ/ｓ] The relati tion onsh ship p 150 between en time and (98.8g) velocit ity 100 (148.8g) 50 (248.8g) 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 時間ｔ [秒]
Action and Reaction Law (Third law of motion) Repulsion force each other, without touching S N S N S N N S N S N S S N On the frictionless table High school textbook
Circular magnet Small Neodymium magnet are arranged In a circular form 図 8-2
改良型 Demonstration 小型ネオジム磁石 using circular magnet, under strobe flash light
Action and reaction, using jumping frog Usually, difficult to see the force itself
Demonstration on practice problem On the smooth surface C, there is an object D (M kg) on the smooth slope B, of which angle is Θ . Another 0bject A (m kg) is placed on the slope quietly. Then, the object C slide down on the slope because of no friction between the surfaces. Questions: 1) What is the acceleration of A against C ( in X, Y component) 2) What is the relative acceleration of A against D 3) What is the relative acceleration of D against C We can demonstrate using the frictionless plate and frictionless slope.
Free falling object Falling object on a slope Frictionless slope Mgsinθ Ｍｇ Mg Mg cosθ M ｇ Ｆ＝Ｍｇsinθ Ｆ＝Ｍｇ a= ｇsinθ(small) a= a= ｇ Acceleration become small by using slope, when Θ ＝１° acceleration =( １ / ６０ )g We can see the phenomena as slow motion, easy to understand.
Can measure the force to the slope direction Inclining fricti tionless ta table Smooth th slope
Free-fall on the smooth slope Regardless of the mass, falling is the same We can see in slow motion
Uniform acceleration The relation of distance and time Time vs. length motion on the Angle of slope ： 0.8 inclined beads plate 1.20 time ： ~3.5 sec 1.00 acceleration ： 0.13m/s 2 Distance(m) 0.80 0.60 0.40 0.20 0.00 0.00 1.00 2.00 3.00 4.00 Time(s) Time vs. velocity The relation of velocity and time 0.6 0.5 Velocity（m/s） 0.4 0.3 0.2 0.1 0.0 0.0 1.0 2.0 3.0 4.0 Time（ｓ） Measurement can be made using a stopwatch (very instructive)
Monkey Hunting Vertical direction motion is the same between the monkey and the stone ｘ方向と、ｙ方向の運動は独立。 サルも弾もｙ方向に対しては 同じ落下運動をする。 Commercial equip. ¥39,000
Experiment of monkey hunting using the inclined beads plate One --Two--Start Both Monkey and stone, Regardless of the speed the motion of The stone can attack the Y direction is the same . The monkey monkey The Motion takes place slowly ⅹ stone y 1 0 Stone is shot aiming the monkey
What angle gives the most far distance? (under the same initial speed) x v cos t 0 1 2 ( ｇ ` ＝ｇ sinθ) y gt v sin t ` 0 2 ⅹ gx ` y x tan 2 2 2 v cos y 0 2 tan 2 v cos 0 x 0 , x g 2 v sin 2 0 g x sin 2 1 max 0 45
Many Application of Frictionless Plate
Horizontal spring vibration
Model for diatomic molecule Concept of 3 kinds motion: Vibrational, Rotational, Translational
Non-gravity (Weightlessness) demo. beads beads In a elevator, which freely fall. During the falling on the frictionless slope(~20 o ) , no expansion of the spring
Collision Completely exchange Small one is repelled
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