Kenapa Air Panas Lebih Cepat Membeku Daripada Air Biasa???

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Sebenarnya fenomena ini sudah ditemukan tahun 1963 dulu kala oleh seorang pelajar SMP di Tanzania. Nama pemuda itu adalah Erasto B. Mpemba, ia menemukannya secara tak sengaja saat mengikuti kelas memasak. Saat itu ia ingin membekukan adonan ice cream panas dan ia mendapati bahwa adonannya membeku lebih cepat daripada punya teman2-nya yang memasukkan ke freezer saat adonan uda dingin.

Setelah lulus, ia melanjutkan sekolah di Mkwawa Secondary School, Iringa, Tanzania (setingkat SMU). Pada suatu saat, Kepala sekolah-nya suatu ketika mengundang Dr. Denis G. Osborne dari University College in Dar Es Salaam untuk memberikan kuliah tentang fisika. Setelah selesai memberikan kuliah, Erasto Mpemba bertanya kepadanya mengenai kejadian aneh saat memasak ice cream, gini pertanyaannya

Jika Anda mengambil dua kontainer yang sama dengan volume air yang setara, yang satu bersuhu 35 ° C (95 ° F) dan yang lainnya di 100 ° C (212 ° F), dan menempatkan mereka ke freezer, yang suhunya 100 ° C (212 ° F) membeku lebih dahulu. Mengapa?

Mpemba menjadi bahan ejekan teman-teman dan gurunya saat melontarkan pertanyaan itu. Tapi Dr. Osborne dengan rasa ingin tahu kemudian bereksperimen mengenai masalah ini pada saat kembali ke tempat kerjanya dan mengkonfirmasi bahwa apa yang ditemukan Erasto’s adalah benar. Kemudian mereka (Mpemba dan Dr. Osborne) menerbitkan hasilnya bersama-sama pada tahun 1969.  Dan kemudian fenomena ini diseubt Mpemba Effect sesuai dengan nama penemunya.

Jurnalnya : 

  • Mpemba, Erasto B.; Osborne, Denis G. (1969). “Cool?”. Physics Education (Institute of Physics) 4: 172–175
  • Mpemba, E B; Osborne, D G (1979). “The Mpemba effect”. Physics Education (Institute of Physics) 14: 410–412

Teori

Penjelasan yang mungkin dari fenomena ini, walaupun masih diperdebatkan adalah :

Evaporation/Penguapan, yang dijelaskan dalam buku Jearl Walker, The Flying Circus of Physics (Wiley, 1975)] bergantung pada fakta bahwa air panas menguap lebih cepat, sehingga pada saat yang sama berikutnya akan terjadi berkurangnya massa air panas, hal ini akan menyalip air dingin dan membeku lebih dahulu, karena lebih rendah massa, semakin pendek waktu pembekuan.

Container and Surroundings / Kontainer dan Sekitarnya : Kontainer di mana air diletakan, serta permukaan atau lingkungan di mana ia ditempatkan, juga dapat mempengaruhi proses pendinginan berbeda pada temperatur yang berbeda.

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Introduce My Self

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Name              : Ellya Estri Septianingrum
Nick                 : Ellya
PDB                  : Tuban, September 5th 1992
Religion         : Islamism
Blood group :B
Address         : remote areas in Rengel makes you desperate to reach it (already evidenced by my fiancé candidates)
Status              : single (plan on getting married but do not know when the completion), a member of the IPhE family 2010 State                      University of Surabaya
Hobby            : watch movies via your laptop, listen to the song that the lyric is strange
Activities      : FB, twitter, “butterfly” , hanging out, College
Contact          :
Blog                 : ellyaesstri.wordpress.com
email               : ellya.purnomo@gmail.com
g-talk              : ellya.purnomo
Self description : I don’t know how myself, maybe you can ask my friends or maybe a girlfriend of mine who often became a target when I was in bad mood. Anyway if I’ve been hurt by somebody then I’ll shut the door, hehehe.
Motto : times is money
Principle :
The contains, the more looked down
Talk less, do more, as the rule
democrazy

Plasma Physicist

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A Princeton plasma physicist is at the beach when he discovers an ancient looking oil lantern sticking out of the sand. He rubs the sand off with a towel and a genie pops out. The genie offers to grant him one wish. The physicist retrieves a map of the world from his car an circles the Middle East and tells the genie, ‘I wish you to bring peace in this region’.
After 10 long minutes of deliberation, the genie replies, ‘Gee, there are lots of problems there with Lebanon, Iraq, Israel, and all those other places. This is awfully embarrassing. I’ve never had to do this before, but I’m just going to have to ask you for another wish. This one is just too much for me’.
Taken aback, the physicist thinks a bit and asks, ‘I wish that the Princeton tokamak would achieve scientific fusion energy break-even.’
After another deliberation the genie asks, ‘Could I see that map again?’

Physicist, Engineer, and Mathematician

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What is the difference between a physicist, an engineer, and a mathematician?
If an engineer walks into a room and sees a fire in the middle and a bucket of water in the corner, he takes the bucket of water and pours it on the fire and puts it out.
If a physicist walks into a room and sees a fire in the middle and a bucket of water in the corner, he takes the bucket of water and pours it eloquently around the fire and lets the fire put itself out.
If a mathematician walks into a room and sees a fire in the middle and a bucket of water in the corner, he convinces himself there is a solution and leaves.

Thermodynamics

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Thermodynamics

Thermodynamics
by George Hartley Bryan

Publisher: Teubner 1907
Number of pages: 232

Description:
The author adopted the principles of conservation and degradation of energy as the fundamental laws of thermodynamics, and deduced the ordinary forms of these laws from those principles. Chapters I, II contain a general sketch of the most important facts and definitions of thermodynamics as based on experience.

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Download or read it online here:

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(multiple formats)

Thermodynamics: Fundamentals and Its Application in Science

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Thermodynamics: Fundamentals and Its Application in Science

Thermodynamics: Fundamentals and Its Application in Science
by Ricardo Morales-Rodriguez (ed.)

Publisher: InTech 2012
ISBN-13: 9789535107798
Number of pages: 542

Description:
The book goes from the fundamentals up to several applications in different scientific fields: Classical Thermodynamics, Statistical Thermodynamics, Property Prediction in Thermodynamics, Material and Products, Non Equilibrium and Thermodynamics in Diverse Areas.

Home page url

Download or read it online here:

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(14MB, PDF)

An Introduction to the Theory of Relativity

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An Introduction to the Theory of Relativity

An Introduction to the Theory of Relativity
by L. Bolton

Publisher: E.P. Dutton & Co. 1921
ISBN/ASIN: B005GE811A
Number of pages: 210

Description:
The Theory of Relativity may very well prove to be the most important single contribution yet made to intellectual thought. If the theory is true it means nothing less than that physical science has at length broken through the crust of the phenomenal and apparent. The mechanism of nature is to be sought in something as yet conceivable only mathematically.

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Download or read it online here:

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(multiple formats)

Modern Relativity

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Modern Relativity

Modern Relativity
by David Waite

Publisher: modernrelativitysite.com 2005

Description:
This is a text book tutorial on Albert Einstein’s theories of special and general relativity. It is assumed that the reader has an understanding of mathematics through calculus and partial differential equations. The relevant tensor calculus is presented throughout as needed.

Home page url

Download or read it online here:

Read online

(online html)