Rabu, 27 Maret 2013

Theoretical Study of Air Pressure


My group choose Air Pressure for our theoretical study.
Air pressure is the force exerted (applied is simpler)by the weight of a column of air above a particular location. the exemple of air pressure are drinking with the straw and injection. Air pressure has relate between science and technology, the example of daily life are plane with our life modern to go another country easily, and then syringe in the modern of medicine. and this is our experiment to complete the theoritical study about air pressure. when A flame goes out inside of an upside down jar and, like magic, the jar is stuck to a plate. You might think that the jar has sucked right to the plate, but we’ll explain why this trick is actually a result of pushing! The Stuck Like Glue experiment is an incredible demonstration of the power of air pressure and a great way to help explain the way that forces work.

   if you have to watch the video, maybe you are feeling curious now, how does it work? okey i will explain it more than on video. 
    
   When the piece of paper inside of the overturned jar is lit, the air inside the jar is heated, causing it to expand. When the flaming paper is extinguished, the air inside the jar cools and contracts, leaving a void of air within the jar. This is an example of an imperfect vacuum. When you think of a vacuum, you think of suction, but scientists like to avoid the term "suck," and instead rely on the pushing forces from outside. With the vacuum inside the jar, air from outside really wants to get inside. Were it not for the wet paper towel, the outside air would succeed and the vacuum would be no more. However, the water in the paper towel effectively stops the air from rushing back into the jar. Water (as well as other substances) has two properties called adhesion and cohesion. Adhesion is water's ability to stick to other materials, and cohesion is, you guessed it, water's ability to stick to itself. When the flaming paper is extinguished and you add pressure onto the jar, the adhesion and cohesion of the water create an air-tight seal between the plate, paper towel, jar, and water.This air-tight seal means that air is constantly trying to push its way up and into the jar without success. The air pushing at the seal creates the phenomenon of the plate sticking to the mouth of the jar.

   the related between this experiment with science and technology very wide, maybe we can choose one example that the work is near with this experiment, for example Cupping technology in medicine. Cupping and this experiment has a lil bit same materials and 'how does it work'. i will emphasize about science and technology here. since Cupping has been found, i am sure that it is happen cause a modern and technology, because science is come from nature and human's brain. and technology is the application of the science. 


left: the experiment || right: cupping


   by the way, talking about air pressure, i remember that air pressure has a related with bernoulli's principle.

Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease inpressure or a decrease in the fluid's potential energy. Bernoulli's principle is named after the Swiss scientist Daniel Bernoulli who published his principle in his book Hydrodynamica in 1738.

Daniel Bernoulli


Bernoulli's principle can be applied to various types of fluid flow, resulting in what is loosely denoted as Bernoulli's equation. In fact, there are different forms of the Bernoulli equation for different types of flow. The simple form of Bernoulli's principle is valid for incompressible flows (e.g. most liquid flows) and also for compressible flows (e.g. gases) moving at low Mach numbers (usually less than 0.3). More advanced forms may in some cases be applied to compressible flows at higher Mach numbers (see the derivations of the Bernoulli equation).

Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of mechanical energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy and potential energy remain constant. Thus an increase in the speed of the fluid occurs proportionately with an increase in both its dynamic pressure and kinetic energy, and a decrease in its static pressure and potential energy. If the fluid is flowing out of a reservoir, the sum of all forms of energy is the same on all streamlines because in a reservoir the energy per unit volume (the sum of pressure and gravitational potential ρ g h) is the same everywhere.
Bernoulli's principle can also be derived directly from Newton's 2nd law. If a small volume of fluid is flowing horizontally from a region of high pressure to a region of low pressure, then there is more pressure behind than in front. This gives a net force on the volume, accelerating it along the streamline.
Fluid particles are subject only to pressure and their own weight. If a fluid is flowing horizontally and along a section of a streamline, where the speed increases it can only be because the fluid on that section has moved from a region of higher pressure to a region of lower pressure; and if its speed decreases, it can only be because it has moved from a region of lower pressure to a region of higher pressure. Consequently, within a fluid flowing horizontally, the highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.




 sources: 
http://en.wikipedia.org/wiki/Bernoulli's_principle
http://www-history.mcs.st-andrews.ac.uk/PictDisplay/Bernoulli_Daniel.html
Stuck Like Glue - Air Pressure Trick at Steve Spangler Science



Selasa, 12 Maret 2013

Berfikir Ilmiah



Metode ilmiah adalah proses keilmuan untuk memperoleh pengetahuan secara sistematis.

Paradigma Skolastik 

Paradigma adalah seperangkat asumsi, konsep, nilai, dan praktik yang di terapkan dalam memandang realitas dalam sebuah komunitas yang sama, khususnya, dalam disiplin intelektual. hal ini berarti dibutuhkan dalam berfikir secara ilmiah, antara lain:

1. Tujuan pencarian adalah konsep yang terpenting.

2. Tidak ada perbedaan antara kenyataan dan mimpi.
3. Membangun alam.
4. Agama dianggap kepentingan unggul dan memiliki prioritas yang baik.

Renaissance paradigma


1. Kedatangan abad ke-16

2. Ilmu diakui mampu menjelaskan fenomena.
3. Ilmu itu sendiri menjadi sumber untuk pengembangan teknologi baru
4. Dunia mekanistik dan determinisme.
5. Awal dari abad ke-18.
6. Tradisional dan Spekulasi terganti dengan rasionalisme.
7. Dunia playsical.

Tokoh-tokoh dalam metode ilmiah


1. Nicolaus Coppernicus (Geocentric) 1473-1543.

2. Giordano Bruno (Infinite Universe) 1548-1600.
3. Tyco Brahe 1546-1601 & Johannes Keppler 1571-1630.
4. Galileo Galilei 1546-1642.

Unsur-unsur karya ilmiah


1. Pertanyaan.

2. Hipotesis.
3. Bebas.
4. Tergantung.
5. Dikontrol variabel.

Unsur-unsur metode ilmiah


1. Kontrol Grup.

2. Data.
3. Kesimpulan.
4. Hasil.
5. Tes ulang


Jumat, 01 Maret 2013

Berpikir Kritis

           Berpikir Kritis adalah pemikiran luas yang didasari oleh hal-hal yang membuat sebuah argumen yang kita utarakan menjadi jelas. dalam berpikir kritis ada banyak hal yang perlu diperhatikan, antara lain:

  1. Presisi
  2. Akurasi
  3. Relevan
  4. Kedalaman
  5. Logika
  6. Luas
  7. Kejelasan
        Presisi merupakan ketelitian, dalam Berpikir kritis kita butuh ketelitian terhadap apa yang kita pikirkan dan apa yang akan kita argumenkan. Akurasi merupakan keakuratan, dalam menyampaikan argumen yang didahului dengan berpikir kritis juga perlu untuk memikirkan keakuratan dari informasi. tidak mungkin jika kita akan berpikir tanpa adanya bukti dan dasar yang akurat. Relevan adalah bersangkut paut, maksudnya adalah, ketika kita berpikir kritis, kesinambungan antara hal satu dan lainnya harus ada, karena sesuatu hal memiliki sebab akibat yang jelas, agar sebuah argumen nantinya akan mempunyai alasan yang mengkokohkan. Kedalaman dalam berpikir juga sangat diperlukan karena, dalam berpikir kritis kita dibutuhkan untuk tidak berpikir pendek dan cepat mengambil kesimpulan dengan menggunakan logika yang tepat dan masuk akal. keluasan dalam berpikir sama dengan kedalaman, serta kejelasan dari apa yang kita pikirkan.

          Selain itu, fondasi dari berpikir kritis juga harus disiapkan. karena berpikir sama dengan komunikasi, yang meiliki aspek-aspek penting. berikut model komunikasi,

  1. Harus ada orang yang berbicara dan mendengar.
  2. ada yang disampaikan.
  3. bahasa yang sama untuk mengenali apa yang dikatakan.
  4. emosi, wawasan, pengalaman budaya.
  5. harus jelas apa yang disampaikan,