Messages In This Digest (4 Messages)

1a.: Re: Terikat ruang-waktu From: handhika ramadhan

2a.: Re: kok ga ke setrum???! From: Indra Sutriadi ÇáÔÇÝÚÆ
2b.: Re: kok ga ke setrum???! From: Eka Subyantara

3.: Teaching by questioning (rather than teaching by telling) From: Gea O.F. Parikesit

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1a.: Re: Terikat ruang-waktu

Posted by: "handhika ramadhan" isaacnewtonid@yahoo.com isaacnewtonid

Thu Jan 1, 2009 3:46 pm (PST)

Ingin menanggapi sedikit....bukan masalah metafisika nya (life after death yg anda jabarkan), tapi mengenai konsep extra dimensions nya.....

Topik extra dimensions memang selalu menarik dikaji dalam fisika teori. Pertama kali dipostulatkan oleh Theodor Kaluza di tahun 1921 untuk menyatukan gravitasi dan elektromagnetik (dua gaya fundamental yg baru diketahui pada era itu). Dengan memperluas ruang waktu menjadi 5 dimensi dan menurunkan persamaan Einstein nya, Kaluza menunjukkan bahwa persamaan Maxwell untuk elektromagnetik secara natural muncul dari dimensi tambahan tersebut. Hasil ini sangat menarik, hingga bahkan menarik perhatian Einstein waktu itu. Salah satu problem dari teori ini,
tentu saja, adalah kenyataan bahwa kita tidak pernah merasakan dimensi kelima tersebut. Jika dimensi kelima ini eksis, maka mengapa kita tidak pernah mengetahuinya? Masalah ini dipecahkan oleh Oscar Klein dengan mempostulatkan bahwa dimensi kelima ini terkompaktifikasi; bahwa dimensi tambahan tersebut itu tidaklah memanjang tanpa batas seperti halnya 4 dimensi ruang-waktu , melainkan bersifat periodik, curled-up seperti halnya silinder dengan diameternya merupakan ukuran dimensi kelima tersebut. Biasanya diambil Planck length sebagai diameter dimensi ini.

====================================
Where the mind is without fear and the head is held high....
Where the knowledge is free...
Where the world has not been broken up into fragments by narrow domestic walls...
Where words come out from the depth of truth...
Where tireless striving stretches its arms toward perfection....
Where the clear stream of
reason has not lost its way into the dreary sand of dead habit....
Where the mind is led forward by Thee into ever-widening thought and action....
Into that Heaven of Freedom, My God, let my country awake.

- Rabindranath Tagore in "Gitanjali" -

--- On Mon, 5/26/08, arifianto keren <arifianto_ipb@yahoo.com> wrote:
From: arifianto keren <arifianto_ipb@yahoo.com>
Subject: [FISIKA] Terikat ruang-waktu
To: fisika_indonesia@yahoogroups.com, "Fisika ipb" <Alumni_FisikaIPB@yahoogroups.com>
Date: Monday, May 26, 2008, 12:42 AM

Hal yang akan saya diskusikan disini mungkin terlalu abstrak dan hanya pemikiran saya saja.
Dalam pembahasan Teori Relativitas Einstein dibahas mengenai paduan ruang-waktu dalam dunia empat dimensi. Dalam aljabar linier mengenai Dimensi ruang ke-N (saya lupa nama sub babnya) dalam ruang N dimensi memungkinkan adanya ruang (N-1) dimensi, misalnya dalam ruang 3 dimensi kita dapat membuat (menggambar) 1 dimensi (garis) dan 2 dimensi (luasan) atau 3 dimensi (volum). tetapi jika ada makhluk yang hidup dalam ruang dua dimensi tidak akan pernah bisa membayangkan adanya dunia 3 dimensi atau empat dimensi.

Hal yang saya pikirkan adalah kita yang dari lahir hingga nanti menjelang kematian, sadar bahwa kita hidup dalam dunia 4 dimensi (ruang-waktu) tidak akan pernah bisa menyadari adanya dimensi ke-5 atau ke-6 dst. misal ada seekor kutu yang cerdas dari sejak menetas hidup diatas sehelai benang yang tipis. selama hidupnya yang dia tahu hanya maju atau mundur, tidak pernah dia mengalami belok ke kiri atau ke kanan, ke atas atau ke bawah. jika kutu tersebut dipindahkan ke atas sebuah bidang yang luas maka ia akan bingung karena selama hidupnya tidak ada konsep luas. kehadiran dimensi "baru" ini akan mengubah seluruh pola pikirnya tentang dunianya.

Alam semesta ini sangat luas, kita tidak akan pernah bisa mengetahui batasnya. mungkin saja sebenarnya ada dimensi lain di semesta ini yang tidak pernah kita sadari karena semua yang kita lihat, dengar, rasakan, semuanya terikat dengan dunia 4 dimensi yakni ruang (3 dimensi) dan waktu (1 dimensi). sebagai contoh (walau belum tentu benar), kita selama ini "menganggap" dimensi wakti hanya terdiri atas 1 dimensi (hanya bisa maju) karena hanya itulah yang bisa kita "rasakan" dan alami. maka semua keputusan dan pola pikir kita berdasarkan pengalaman kita itu. andaikan seorang manusia dipindahkan (seperti kasus kutu sebelumnya) dari dunia waktu 1 dimensi ke dunia waktu 2 dimensi, maka pasti manusia tersebut akan bingung karena apa yang ia alami saat itu sama sekali berbeda dengan pengalamannya seumur hidupnya.

Keputusan yang diambil oleh setiap makhluk semuanya berdasarkan pengalaman dan pengetahuan yang ia dapatkan selama hidupnya. Maka banyak orang berselisih pendapat mengenai suatu hal karena mereka memiliki pengalaman dan pengetahuan yang berbeda (seperti cerita tiga orang buta yang berselisih tentang bentuk gajah). Contohnya kehidupan setelah mati, ada orang yang percaya ada kehidupan setelah mati ada yang tidak percaya. hal ini analogi dengan ada orang yang percaya adanya dimensi lain selain 4 dimensi yang kita ketahui dan ada yang tidak percaya. perselisihan ini terjadi karena perbedaan pengalaman dan pengetahuan (bukan berarti ada yang pernah mati lalu hidup kembali lho). menurut saya kehidupan setelah mati analogi dengan kutu yang dipindahkan dari 1 dimensi ke 2 atau 3 dimensi atau bahkan ia dipindahkan ke dimensi yang sama sekali berbeda dengan yang sebelumnya. dengan kata lain saat makhluk hidup mati maka (menurut saya) ia tidak
lagi terikat dengan dimensi ruang-waktu, tidak ada luas maupun sempit, tidak ada lama atau sebentar semuanya tergantung individu masing-masing. tiap individu akan memiliki dimensi mereka sendiri. sekali lagi ini hanya pemikiran yang abstrak. silahkan jika ada yang ingin menanggapi.

Arifianto
"cool like an ice"

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2a.: Re: kok ga ke setrum???!

Posted by: "Indra Sutriadi ÇáÔÇÝÚÆ" indra.sutriadi@gmail.com

Fri Jan 2, 2009 5:45 am (PST)

Pada 1 Januari 2009 16:46, Andri Husein <andri84@yahoo.com> menulis:
> Pertanyaan hebat. Maaf aku jg ga tahu jawabnnya dan klo ada yang tahu kasih
> tahu ya? Sapa tahu bisa jadi tema skripsi lho...

Oya, mana jawabannya nih...???
Mungkin Pak Muzi bisa membantu dan bisa dibuatkan percobaan kecilnya
yang lebih menyenangkan.

> --- On Tue, 30/12/08, hinata_freak_87 <hinata_freak_87@yahoo.co.id> wrote:
>
> From: hinata_freak_87 <hinata_freak_87@yahoo.co.id>
> Subject: [FISIKA] kok ga ke setrum???!
> To: fisika_indonesia@yahoogroups.com
> Date: Tuesday, 30 December, 2008, 12:51 PM
>
> aslm
>
> mo tanya dong,,sy kan punya pompa air untuk akuarium yang di
> tenggelemin di dasar,,ktika itu kabel yang di airnya ada yang bocor
> (terbuka), pas saya pegang airnya ternyata nyetrum (wajar), tapi kok
> ikan yang ada di kolam ga kesetrum y? apa karena volasenya yang
> terlalu rendah??
> ada lagi,sypernah liat ada kabel dari tiang listrik PLN yang
> putus,trus kabelnya nyebur ke sungai sehingga menciptakan percikan api
> yang cukupbesar, tapi ada ikan yang berenang diantara ujung kedua
> kabel ga kesetrum, knapa y??
> ada lagi, ada satu metode nangkep ikan dengan cara disetrum, jadi
> tegangan dari baterai (biasanya dipakai aki) dialiri ke ujung-ujung
> kawat, kemudian kawat itu di celupkan ke air, di jamin ikan yang ada
> di antara kedua kawat bakal sekarat!
> kenapa bisa beda?apa karena yang satu pake AC yang satu lagi pake DC?
> trims

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2b.: Re: kok ga ke setrum???!

Posted by: "Eka Subyantara" eka.subyantara@widyatama.ac.id eka_subyantara

Fri Jan 2, 2009 5:47 am (PST)

Mudah-mudahan jawaban ini dapat berguna ... :-)
Untuk ketiga kasus tersebut jawabannya bermuara pada satu fakta, yaitu ADA
ATAU TIDAKNYA ARUS LISTRIK YANG MENGALIR PADA MEDIUM AIR YANG DILEWATI IKAN
TERSEBUT

1. Kasus akuarium: kabel bocor hanya satu titik tegangan, sehingga tidak ada
arus mengalir pada air, maka ikannya aman-aman saja. Anda kakinya nempel di
bumi, maka arus mengalir melalui tubuh anda ke bumi (kecuali anda terisolasi
misalnya dengan naik kursi plastik kering). Peristiwa ini serupa dengan
burung yang hinggap di kawat listrik SUTET yang juga bisa bercengkrama ria
dengan teman-temannya.
2. Kasus kabel PLN nybur sungai: Dua kabel boleh jadi tegangannya sama, jadi
tidak ada arus mengalir di antara dua kabel.
3. Kasus Penangkap ikan pake aki: Tegangan aki memang DC tegangan rendah
(biasanya digunakan 12V), tetapi dinaikkan dulu tegangannya menggunakan
komutator dan trafo step up, sehingga tercipta pulsa tegangan transien yang
bisa mencapai ribuan volt dengan arus rendah dalam waktu sesaat saja. Dua
konduktor akan dimasukkan ke air pada jarak tertentu, maka ikan yang berada
di antaranya pasti akan "kesetrum" karena ada arus yang melewati air da
badan ikan tersebut, sehingga melumpuhkan sistem syaraf geraknya, dan ini
yang Anda sebut dengan "sekarat".

Wallahu 'alam bissawab, Allah-lah yang lebih mengetahui penjelasannya.

HanyaBerusahaMenyampaikanApaYangDirasaBenarUntukSaatIni
- eka -

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3.: Teaching by questioning (rather than teaching by telling)

Posted by: "Gea O.F. Parikesit" geaofp@yahoo.com geaofp

Fri Jan 2, 2009 5:47 am (PST)

Salam,

Artikel di bawah ini saya copy-paste dari:
http://www.sciencemag.org/cgi/content/full/323/5910/50

Sejumlah artikel lain, di Science "special issue" edisi yang sama, juga terfokus ke masalah pendidikan:
http://www.sciencemag.org/content/vol323/issue5910/index.dtl#special-issue
Bagi yang berminat memperoleh artikelnya tapi tidak punya akses ke artikel yg diinginkan, silakan kontak via japri.

Salam,
Gea O.F. Parikesit
http://gea.ari.googlepages.com/home

=======

Science 2 January 2009:
Vol. 323. no. 5910, pp. 50 - 51
DOI: 10.1126/science.1168927 Prev | Table of Contents | Next
Perspectives
EDUCATION:
Farewell, Lecture?Eric Mazur*
Discussions of education are generally predicated on
the assumption that we know what education is. I hope to convince you
otherwise by recounting some of my own experiences. When I started
teaching introductory physics to undergraduates at Harvard University,
I never asked myself how I would educate my students. I did what my
teachers had done--I lectured. I thought that was how one learns. Look
around anywhere in the world and you'll find lecture halls filled with
students and, at the front, an instructor. This approach to education
has not changed since before the Renaissance and the birth of
scientific inquiry. Early in my career I received the first hints that
something was wrong with teaching in this manner, but I had ignored it.
Sometimes it's hard to face reality.
Click here. Students continually discuss concepts
among themselves and with the instructor during class. Discussions are
spurred by multiple-choice conceptual questions that students answer
using a clicker device. See supporting online text for examples of such
"clicker questions."
CREDIT: JON CHASE/HARVARD UNIVERSITY
When I started teaching, I prepared lecture notes and then taught from
them. Because my lectures deviated from the textbook, I provided
students with copies of these lecture notes. The infuriating result was
that on my end-of-semester evaluations--which were quite good
otherwise--a number of students complained that I was "lecturing
straight from (his) lecture notes." What was I supposed to do? Develop
a set of lecture notes different from the ones I handed out? I decided
to ignore the students' complaints.
A few years later, I discovered that the students were right. My
lecturing was ineffective, despite the high evaluations. Early on in
the physics curriculum--in week 2 of a typical introductory physics
course--the Laws of Newton are presented. Every student in such a
course can recite Newton's third law of motion, which states that the
force of object A on object B in an interaction between two objects is
equal in magnitude to the force of B on A--it sometimes is known as
"action is reaction." One day, when the course had progressed to more
complicated material, I decided to test my students' understanding of
this concept not by doing traditional problems, but by asking them a
set of basic conceptual questions (1, 2).
One of the questions, for example, requires students to compare the
forces that a heavy truck and a light car exert on one another when
they collide. I expected that the students would have no trouble
tackling such questions, but much to my surprise, hardly a minute after
the test began, one student asked, "How should I answer these
questions? According to what you taught me or according to the way I
usually think about these things?" To my dismay, students had great
difficulty with the conceptual questions. That was when it began to
dawn on me that something was amiss.
In hindsight, the reason for my students' poor performance is simple.
The traditional approach to teaching reduces education to a transfer of
information. Before the industrial revolution, when books were not yet
mass commodities, the lecture method was the only way to transfer
information from one generation to the next. However, education is so
much more than just information transfer, especially in science. New
information needs to be connected to preexisting knowledge in the
student's mind. Students need to develop models to see how science
works. Instead, my students were relying on rote memorization.
Reflecting on my own education, I believe that I also often relied on
rote memorization. Information transmitted in lectures stayed in my
brain until I had to draw upon it for an exam. I once heard somebody
describe the lecture method as a process whereby the lecture notes of
the instructor get transferred to the notebooks of the students without
passing through the brains of either (3). That is essentially what is happening in classrooms around the globe.
Since this agonizing discovery, I have begun to turn this traditional
information-transfer model of education upside down. The responsibility
for gathering information now rests squarely on the shoulders of the
students. They must read material before coming to class, so that class
time can be devoted to discussions, peer interactions, and time to
assimilate and think (4). Instead of teaching by telling, I am teaching by questioning.
I now structure my time during class around short, conceptual
multiple-choice questions. I alternate brief presentations with these
questions, shifting the focus between instructor and students. The
questions address student difficulties in grasping a particular topic
and promote thinking about challenging concepts. After posing the
question, I give the students 1 to 2 minutes to think, after which each
must commit to an individual answer. They do this by submitting their
answers using handheld devices called "clickers" (see the figure).
Because of the popularity of these devices, questions posed this way
are now often referred to as "clicker questions." The devices transmit
the answers to my computer, which displays the distribution of answers.
If between 35% and 70% of the students answer the question correctly, I
ask them to discuss their answers and encourage them to find someone in
the class with a different answer. Together with teaching assistants, I
circulate among the students to promote productive discussions and
guide their thinking. After several minutes of peer discussion, I ask
them to answer the same question again. I then explain the correct
answer and, depending on the student answers, may pose another related
question or move on to a different topic. This approach has two
benefits: It continuously actively engages the minds of the students,
and it provides frequent and continuous feedback (to both the students
and the instructor) about the level of understanding of the subject
being discussed.
I often meet people who tell me they have implemented this "clicker
method" in their classes, viewing my approach as simply a technological
innovation. However, it is not the technology but the pedagogy that
matters (5).
Unfortunately, the majority of uses of technology in education consist
of nothing more than a new implementation of old approaches, and
therefore technology is not the magic bullet it is often presumed to
be. Although clickers offer convenience and (at least for now) an
amount of trendiness that appeals to students, the method can be
implemented with flash cards, which are inexpensive and never prone to
technological glitches (6).
Data obtained in my class and in classes of colleagues worldwide, in a
wide range of academic settings and a wide range of disciplines, show
that learning gains nearly triple with an approach that focuses on the
student and on interactive learning (7, 8).
Students are given the opportunity to resolve misunderstandings about
concepts and work together to learn new ideas and skills in a
discipline. Most important, students not only perform better on a
variety of conceptual assessments, but also improve their traditional
problem-solving skills (9).
Also, data show that such interactive engagement helps to reduce the
gender gap that exists in introductory physics classrooms (10).
So, evidence is mounting that readjusting the focus of education from
information transfer to helping students assimilate material is paying
off. My only regret is that I love to lecture.
References and Notes
1. D. Hestenes, M. Wells, G. Swackhamer, Phys. Teach. 30, 141 (1992).
2. A version of (1) revised in 1995 by I. Halloun, R. Hake, E. Mosca, and D. Hestenes is available in (4).
3. D. Huff, How to Lie with Statistics (Norton, New York, 1954).
4. E. Mazur, Peer Instruction: A User's Manual (Prentice Hall, Upper Saddle River, NJ, 1997).
5. M. K. Smith et al., Science 323, 122 (2009).
6. N. Lasry, Phys. Teach. 46, 242 (2008).
7. A. P. Fagen, C. H. Crouch, E. Mazur, Phys. Teach. 40, 206 (2002).
8. N. Lasry, E. Mazur, J. Watkins, Am. J. Phys. 76, 1066 (2008).
9. C. H. Crouch, E. Mazur, Am. J. Phys. 69, 970 (2001).
10. M. Lorenzo, C. H. Crouch, E. Mazur, Am. J. Phys. 74, 118 (2006).Supporting Online Material
www.sciencemag.org/cgi/content/full/323/5910/50/DC1
SOM Text

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