Paradoks daun teh: Perbedaan antara revisi

[[FileBerkas:Tea Leaf Paradox Stirring.ogv|thumbjmpl|Daun teh mengumpul di tengah dan bawah cangkir, bukan di pinggir.]]

[[FileBerkas:Tea leaf Paradox Illustration.svg|thumbjmpl|Garis biru adalah aliran sekunder yang mendorong daun teh ke tengah bawah cangkir.]]

[[FileBerkas:Einstein1921 by F Schmutzer 4.jpg|thumbjmpl|[[Albert Einstein]] menyelesaikan paradoks ini tahun 1926.]]

[[FileBerkas:Visualization-of-secondary-flow-in-river-bend-model-(A.Ya.Milovich, 1913).jpg|thumbjmpl|Visualisasi aliran sekunder dalam model kelok sungai (A.Ya.Milovich, 1913,<ref name="Joukovsky">Hasil-hasilnya disitir di: {{cite journal |author=[[Nikolay Yegorovich Zhukovsky|Joukovsky N.E.]]|year=1914 |title=On the motion of water at a turn of a river|url= |journal=[[Matematicheskii Sbornik]]|volume=28}} Dicetak ulang di: {{cite book |title=Collected works|url= http://books.e-heritage.ru/book/10075055|volume=4|location=Moscow; Leningrad |publisher= |publication-date=1937|pages=193–216; 231–233 (abstract in English)}}</ref> mengalir kanan ke kiri). Garis aliran dekat dasar diwarnai oleh tinta menggunakan sedotan.]]

'''Paradoks daun teh''' menjelaskan [[fenomena]] berpindahnya [[daun teh]] di dalam [[cangkir teh|cangkir]] [[teh]] ke tengah dan bawah cangkir setelah diaduk dengan jalur spiral [[sentrifugal|memusat]]. Pembentukan aliran sekunder dalam [[anulus (matematika)|saluran melingkar]] diteliti oleh [[Joseph Valentin Boussinesq]] pada tahun 1868.<ref>{{cite journal |author=[[Joseph Valentin Boussinesq|Boussinesq J.]]|date=1868|title= Mémoire sur l’influence des frottements dans les mouvements réguliers des fluides |url=http://portail.mathdoc.fr/JMPA/PDF/JMPA_1868_2_13_A17_0.pdf|journal= Journal de mathématiques pures et appliquées 2 e série |publisher= |volume=13 |pages=377–424}}{{Pranala mati|date=Maret 2021 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Perpindahan partikel yang mengambang dekat dasar dalam aliran kelok sungai diteliti oleh A.Ya.Milovich pada tahun 1913.<ref name="Joukovsky"/> Solusinya ditulis oleh [[Albert Einstein]] tahun 1926 dalam makalah yang menjelaskan [[erosi#air|erosi]] [[tepi sungai]] sekaligus membantah [[hukum Baer]].<ref>{{cite journal|last=Bowker|first=Kent A.|date=1988|title=Albert Einstein and Meandering Rivers|journal=Earth Science History|volume=1|issue=1|url=http://www.searchanddiscovery.net/documents/Einstein/albert.htm|accessdate=2008-12-28}}

</ref><ref name= "Naturwissenschaften">{{cite journal|last=Einstein|first=Albert|date=March 1926|title= Die Ursache der Mäanderbildung der Flußläufe und des sogenannten Baerschen Gesetzes|journal=[[Die Naturwissenschaften]]|publisher=Springer|location=Berlin / Heidelberg|volume= 14|pages=223–4|doi=10.1007/BF01510300|bibcode = 1926NW.....14..223E|issue=11 }} [http://www.ucalgary.ca/~kmuldrew/river.html English translation: The Cause of the Formation of Meanders in the Courses of Rivers and of the So-Called Baer’s Law] {{Webarchive|url=https://web.archive.org/web/20090125075105/http://www.ucalgary.ca/~kmuldrew/river.html |date=2009-01-25 }}, accessed 2008-12-28.</ref>

Namun, di dekat bawah dan pinggir terluar, cairan menjadi lambat karena [[gesekan]] dengan cangkir. Gaya sentrifugal inersialnya lebih lemah dan tidak dapat melampaui lengkung tekanan, jadi perbedaan tekanan ini memainkan peran penting bagi aliran air. Ini disebut [[lapisan batas]] atau [[lapisan Ekman]].<ref>{{cite web|url=http://www.stanford.edu/~zhonghua/cee262a/Lecture18.ppt|title= CEE 262A Hydrodynamics Lecture 18 |date=2007|page=35|accessdate=2008-12-29 | format = [[Microsoft PowerPoint|PPT]]}}{{Pranala mati|date=November 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Fenomena ini digunakan untuk mengembangkan teknik baru pemisahan [[sel darah merah]] dari [[plasma darah]],<ref name="Biomicrofluidics">{{cite journal|last=Arifin|first=Dian R.|author2=Leslie Y Yeo |author3=James R. Friend |date=20 December 2006 |title=Microfluidic blood plasma separation via bulk electrohydrodynamic flows|journal=Biomicrofluidics|publisher=[[American Institute of Physics]]|volume=1|issue=1|pages=014103 (CID)|doi=10.1063/1.2409629|url=http://link.aip.org/link/?BIOMGB/1/14103/1|accessdate=2008-12-28|laysummary=http://www.sciencedaily.com/releases/2007/01/070116205009.htm|laysource=[[Science Daily]]|laydate=January 17, 2007|pmid=19693352|pmc=2709949|archive-date=2012-12-09|archive-url=https://archive.today/20121209001530/http://link.aip.org/link/?BIOMGB/1/14103/1|dead-url=yes}}</ref><ref name="abc">{{cite news|url=http://www.abc.net.au/science/news/stories/2007/1828408.htm|title=Einstein's tea-leaves inspire new gadget|last=Pincock|first=Stephen|date=17 January 2007|publisher=[[ABC Online]]|accessdate=2008-12-28}}</ref> memahami sistem tekanan atmosfer,<ref>{{cite web|url=http://www-paoc.mit.edu/paoc/papers/Einstein%27sTeaLeavesTPT.pdf|title=Einstein’s Tea Leaves and Pressure Systems in the Atmosphere|last=Tandon|first=Amit|author2=Marshall, John |accessdate=2008-12-29|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304092149/http://www-paoc.mit.edu/paoc/papers/Einstein%27sTeaLeavesTPT.pdf|dead-url=yes}}</ref> dan memisahkan endapan [[trub]] saat membuat [[bir]].<ref>{{Cite book|title=Beer: tap into the art and science of brewing|url=https://archive.org/details/beertapintoartsc00bamf_914|first=Charles W.|last=Bamforth|edition=2nd|publisher=Oxford University Press|year=2003|isbn=978-0-19-515479-5|page=[https://archive.org/details/beertapintoartsc00bamf_914/page/n72 56]}}</ref>

== Pranala luar ==

* {{en}} {{cite news|url=http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/3291786/Dr-Roger%27s-Home-Experiments.html|title=Dr Roger's Home Experiments|last=Highfield|first=Roger|date=14 January 2008|publisher=[[The Daily Telegraph]]|accessdate=2008-12-28|archive-date=2012-12-09|archive-url=https://archive.today/20121209094124/http://www.telegraph.co.uk/scienceandtechnology/science/sciencenews/3291786/Dr-Roger%27s-Home-Experiments.html|dead-url=yes}}

* {{en}} {{cite web|url=http://www.madsci.org/posts/archives/1997-12/875655758.Ph.r.html|title=Why do particles move towards the center of the cup instead of outer rim?|last=Sethi|first=Ricky J.|date=September 30, 1997|publisher=[[MadSci Network]]|accessdate=2008-12-29}}

* {{en}} {{cite web|url=http://earthweb.ess.washington.edu/roe/ESS514_notes/ch5.pdf|title=Student Notes - Physics of Fluids - ESS 514/414|last=Booker|first=John R.|publisher=Department of Earth and Space Sciences, University of Washington|at=ch.&nbsp;5.8 p.&nbsp;48|accessdate=2008-12-29}} See also figure 25 in [http://earthweb.ess.washington.edu/roe/ESS514_notes/figures.pdf figures.pdf]

* {{en}} {{cite web|url=http://www.ansys.com/solutions/documents/mystery.pdf|title=Mysteries of Engineering Fluid Mechanics|last=Stubley|first=Gordon D.|date=May 31, 2001|publisher=Mechanical Engineering Department, University of Waterloo|accessdate=2008-12-29|archive-date=2009-02-06|archive-url=https://web.archive.org/web/20090206000717/http://ansys.com/solutions/documents/mystery.pdf|dead-url=yes}}

* {{en}} Einstein's 1926 article online and analyzed on ''[https://www.bibnum.education.fr/sciences-de-la-terre/meteorologie/albert-einstein-et-la-tasse-de-de-mme-schrodinger BibNum]'' (click 'Télécharger' for English).