{"id":30810,"date":"2012-12-14T23:42:50","date_gmt":"2012-12-14T20:42:50","guid":{"rendered":"http:\/\/www.fyysika.ee\/uudised\/?p=30810"},"modified":"2012-12-14T23:43:11","modified_gmt":"2012-12-14T20:43:11","slug":"raketi-ja-meteoriiditabamused-on-granulaartasandil-keerulisemad-kui-varem-arvati","status":"publish","type":"post","link":"https:\/\/www.fyysika.ee\/?p=30810","title":{"rendered":"Raketi- ja meteoriiditabamused on granulaartasandil keerulisemad kui varem arvati"},"content":{"rendered":"<p><strong>Kiire kaameraga filmitud m\u00fcrsutabamuste videoanal\u00fc\u00fcs on teadlastele andnud uue pilgu, kuidas toimub meteoriidi v\u00f5i m\u00fcrsu kineetilise energia \u00fclekanne pinnaseosakestele. <\/strong><\/p>\n<div id=\"attachment_30811\" style=\"width: 260px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/www.fyysika.ee\/uudised\/wp-content\/uploads\/2012\/12\/grainsgangup.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-30811\" class=\"size-full wp-image-30811\" src=\"http:\/\/www.fyysika.ee\/uudised\/wp-content\/uploads\/2012\/12\/grainsgangup.jpg\" alt=\"\" width=\"250\" height=\"314\" srcset=\"https:\/\/www.fyysika.ee\/wp-content\/uploads\/2012\/12\/grainsgangup.jpg 250w, https:\/\/www.fyysika.ee\/wp-content\/uploads\/2012\/12\/grainsgangup-238x300.jpg 238w\" sizes=\"auto, (max-width: 250px) 100vw, 250px\" \/><\/a><p id=\"caption-attachment-30811\" class=\"wp-caption-text\">Raketi- ja meteoriiditabamused on granulaartasandil keerulisemad kui varem arvati<\/p><\/div>\n<p>Osutub, et l\u00f6\u00f6ktabamuse energia\u00fclekanne toimub j\u00e4rkj\u00e4rguliselt, mitte pidevalt. Duke-i \u00dclikooli f\u00fc\u00fcsik Rober Behringer kirjeldas eksperimenti j\u00e4rgmiselt:\u201cOli \u00fcllatav avastada, kuiv\u00f5rd eba\u00fchtlane oli m\u00fcrsu kineetilise energia muundumine \u00fclekandumisel m\u00e4rklauda.\u201c Avastust kirjeldav teadust\u00f6\u00f6 avaldati 7. detsembri teadusajakirjas Physical Review letters. Tulemused v\u00f5ivad anda alge uutele ballistiliste l\u00f6\u00f6kide otse- ja j\u00e4relm\u00f5jumudelitele.<\/p>\n<p>Teadlaste varasema \u00fcksmeele kohaselt arvati, et l\u00f6\u00f6kkeha aeglustumine on pidev ning tekkiv helilaine levib l\u00e4bi granulaarse sihtmaterjali \u00fchtlaselt nagu k\u00e4eplaksu l\u00f6\u00f6klaine \u00f5hus. Ent kiirvideokaamera videode anal\u00fc\u00fcs avaldas Behringile ning tema tudengitele Abram Clarkile ja Lou Kondicile hoopis teistsuguse f\u00fc\u00fcsika.<\/p>\n<p>T\u00f6\u00f6s, mida rahastas Ameerika organisatsioon DTRA (<em>Defense Threat Reduction Agency<\/em>), filmiti \u00fclikiirete kaameratega pronksketaste laskmisi fotoelastse granulaarmaterjaliga t\u00e4idetud alusbasseini. Kaadreist j\u00e4lgiti energia\u00fclekannet kettalt graanulmaterjalisse. Anal\u00fc\u00fcs n\u00e4itas, et ketaste kineetiline energia hajus intensiivsete sporaadiliste akustiliste impulssidena alusbasseini graanulite v\u00f5rgustikes ehk j\u00f5us\u00e4brudes (loe <a href=\"http:\/\/jfi.uchicago.edu\/granular\/force_chains.html\">siit<\/a>).<\/p>\n<p>\u201eFenomeni oli s\u00fcndmuste kiire kulgemise t\u00f5ttu raske j\u00e4lgida,\u201c \u00fctles Behringer. Harjumusp\u00e4rane kvaliteetne video kuvab ligikaudu 30 kaadrit sekundis. Helil\u00f6\u00f6kide ning j\u00f5us\u00e4brusid pidi aga filmima kiirusega 40000 kaadrit sekundis, mis on tavavideost 1300 korda kiirem.<\/p>\n<p>Kettad tulistati basseini kuni 6,5 meetrit sekundis (23,4 km\/h). L\u00f6\u00f6gihetkel tekkinud j\u00f5us\u00e4brud kandusid \u00fcle s\u00fcgavale basseini kettasarnaste l\u00f6\u00f6klainetena, mille profiil meenutas vihmaveetorusid.<\/p>\n<p>\u00dclehelikiirusel tulistatud pronkskettad p\u00f5hjustaksid t\u00f6\u00f6r\u00fchma s\u00f5nul sootuks teistsuguse energia\u00fclekande. \u201e\u00dclehelikiirustel ei j\u00f5ua m\u00e4rklaud lihtslat \u00f5igel ajal eest \u00e4ra h\u00fcpata, otsekui m\u00e4rulifilmis. L\u00f6\u00f6kj\u00f5ud p\u00f5rkuks pigem tagasi kui kanduks pinnasesse,\u201c n\u00e4itlikustas Behringer t\u00f6\u00f6anal\u00fc\u00fcsi.<\/p>\n<p>Heli- ja \u00fclehelikiirusel toimuvate l\u00f6\u00f6kide jaoks, mida on ka t\u00f6\u00f6r\u00fchmal plaanis uurida, oleks Behringeri s\u00f5nul vaja teistsuguseid granulaarosakesi. Behringer lisas, et helikiirusest v\u00e4iksema kiirusega liikuva raketi v\u00f5i meteoriiditabamuse puhul kanduks energia vastavalt uuele teooriale m\u00e4rklauda sporaadiliselt ja katkendlikult.<\/p>\n<p>Allikas: <a href=\"http:\/\/phys.org\/news\/2012-12-missile-meteorite-impacts-complex-granular.html\">Phys.org<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Kiire kaameraga filmitud m\u00fcrsutabamuste videoanal\u00fc\u00fcs on teadlastele andnud uue pilgu, kuidas toimub meteoriidi v\u00f5i m\u00fcrsu kineetilise energia \u00fclekanne pinnaseosakestele. Osutub, et l\u00f6\u00f6ktabamuse energia\u00fclekanne toimub j\u00e4rkj\u00e4rguliselt, mitte pidevalt. Duke-i \u00dclikooli f\u00fc\u00fcsik Rober Behringer kirjeldas eksperimenti j\u00e4rgmiselt:\u201cOli \u00fcllatav avastada, kuiv\u00f5rd eba\u00fchtlane oli m\u00fcrsu kineetilise energia muundumine \u00fclekandumisel m\u00e4rklauda.\u201c Avastust kirjeldav teadust\u00f6\u00f6 avaldati 7. detsembri teadusajakirjas Physical Review [&hellip;]<\/p>\n","protected":false},"author":449,"featured_media":30811,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[16],"tags":[],"class_list":{"0":"post-30810","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-teadusuudis","8":"entry"},"_links":{"self":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/30810","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/users\/449"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=30810"}],"version-history":[{"count":0,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/30810\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/media\/30811"}],"wp:attachment":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=30810"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=30810"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=30810"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}