MEKhANIKA

MEKhANIKA [az yun. mechanike (techne) — ilm dar bobi moshinho, hujari sokhtani moshinho), ilmest dar borai harakati, mekhanikii jismhoi materiali va tasirhoi mutaqobile, ki dar in mavrid bayni jismhoi mazkur ba amal meoyand. Harakati mekhaniki gufta dar fazo bo mururi zamon nisbat ba hamdigar tagyir yoftani vaziyati jismho yo zarrahoi onhoro menomand. Chunonchi: harakati jismhoi osmoni, lappishi qishri Zamin, jarayoni havo va bahr harakati haroratii molekulaho, harakati apparathoi gunoguni parishu vositahoi naqliyot va g. Hamchun Mekhanika odatai Mekhanikai klassikiro mefanmand, ki asosi onro qonunhoi mekhanikai Nyuton tashkil medihand va on harakati hama guna jismhoi materialii suratashon az surati nur past (ba gayr az zarrahoi elementari)-ro tadqiq mekunad. Harakati jismhoi surathoshon ba surati nur nazdikro navarili nisbiyat, hodisahoi dokhili atom va harakati zarrahoi elementariro boshad, mekhanikai kvanti meomuzand.

Dar vaqti omukhtani jismhoi materiali Mekhanika az yak qator mafhumhoi abstrakti istifoda mebarad, ki in yo on khosiyati jismhoi realiro inikos msnamoyand: 1) nuqtai materiali — obekti andozaash nochiz, ki massa dorad; in mafhumro dar surati nisbat ba masofahoi taykardai nuqtahoi jismi mutaharrik nazarnogir budani andozahoi on istifoda burdan mumkin ast. 2) Jismi mutlaq sakht — jisme, ki masofai bayni du nuqtai dilkhohi on hamesha betagyir memonad; in mafhum faqat dar surati ba nazar nagiriftani deformasiyai jism ba kor meoyad. 3) Muhiti yaklukhti tagyiryobanda; in mafhum hamon vaqt tatbiqpazir ast, ki agar hangomi omukhtani harakati muhiti tagyiryobanda (jismi deformasiyashavanda. moe, gaz) sokhti molekulavii in muhitro ba nazar nagirem.

Hangomi omukhtani muhithoi yaklukht tajrid (abstraksiya)-hoi zerinro qabul mekunand, ki dar sharoiti muayyan muhimtarin khosiyat yo jihathoi jismhoi voqeiro inikos mekunand. Vobasta ba hamin Mekhanikaro ba Mekhanikai nuqtai materiali, Mekhanikai sistema nuqtahoi materiali, Mekhanikai jinsii mutlaq sakht va Mekhanikai muhiti yaklukht judo mekunand; mekhanikai muhiti yaklukht dar navbati khud ba nazariyai chandiri, nazariyai plastiki, gidromekhaniki, aeromekhanika, dinamikai gaz va g. judo meshavad. Dar har kadomi in faslho vobasta ba kharakteri masalahoi halshavanda statika (talimot dar borai muvozinati jismho dar zimni tasiri quvvaho)» kinematika (talimot dar borai khususiyathoi geometrii harakati jismho) va dinamika (talimot dar borai harakati jismho dar zimni tasiri quvvaho)-ro farq mekunand. Dinamika 2 masalai asosi dorad: yoftani quvvahoe, ki bo tasiri onho harakati mazkuri jism ba amal omada metavonad va muayyan kardani harakati jism dar surati malum budani quvvahoi ba on tasirkunanda.

Baroi halli masalahoi Mekhanika usulhoi gunoguni matematiki istifoda meshavand, ki bisyorashon ba tufayli Mekhanika paydo shuda, inkishof yoftaand. Qonunhoi asosi va prinsiphoero, ki harakati mekhanikii jismho ba onho tobeand, inchunin teoremahoyu muodilahoi umumiero. ki az in qoidahovu prinsipho barmeoyand, Mekhanikai umumi yo nazariyavi meomuzad. Nazariyai lappishho, nazariyai ustuvorii muvozinat va ustuvorii harakat, nazariyai goroskop, mekhanikai jismhoi massaashon tagyiryobanda, nazariyai tanzimi avtomati (nig. Idorai avtomati), nazariyai zarba az faslhoi muhim va mustaqili Mekhanika meboshand.

Mekhanika bo bisyor faslhoi digari fizika robitai zich dorad. Yak qator mafhum va metodhoi Mekhanikaro dar surati ba onho dodani shaklu mazmuni jome dar optika, fizikai statista, Mekhanikai kvanti, elektrodinamika, nazariyai nisbiyat va g. istifoda burdan mumkin ast. Gayr az in, hangomi halli yak qator masalahoi dinamikai gaz, nazariyahoi tarkish, garmiivazshavi dar moehoi mutaharrik va gazho, aerodinamikai gazhoi tunuk, gidrodinamikai magniti va g. dar yak vaqt ham metodu muodilahoi M.-i nazariyavi va ham muvofiqan metodu muodilahoi termodinamika, fizikai molekulavi, nazariyai elektr va g. istifoda meshavand. Mekhanika baroi bisyor faslhoi astronomiya, alalkhusus mekhanikai osmoni ahamiyati kalon dorad.

Qismi bevosita bo tekhnika aloqamandi Mekhanikaro ilmhoi sershumori umumitekhniki va makhsus: gidraekhika, muqovimati materialho, kinematikal mekhanizmho, dinamikai moilii va mekhanizmon, nazariyai oloti giroskopi, ballistikai beruni, dinamikai mushakho, nazariyai harakati vositahoi gunoguni naqliyoti ruizamini, bahri va havoi, nazariyai tanzim va idorai harakati obekthoi gunogun, Mekhanikai binokori va g-kho tashkil medihand, ki hamaashon az muodila va usulhoi Mekhanikai nazariyavi istifoda mebarand. Hamin tariq, Mekhanika yake az asoshoi ilmii bisyor sohahoi tekhnikai zamonavi meboshad.

Mekhanika yake az ilmhoi qadimtarin ba shumor meravad. Vay payvasta ba taraqqiyoti quvvahoi istehsolkunanda, talaboti amaliya paydo shuda, minbad inkishof yoftaast. Ahromhoi Misri Qadim, boqimondahoi inshoothoi azim dar Bobuliston, Khitoy, Khorazm, Surd va Eron shohidi onand, ki dar bunyod kardani in guna inshootho «moshinhoi oddi»—fashang, fona, hamvorii moil, garyara va g. istifoda shudaand. Avvalin risolahoi doir ba Mekhanika, ki to davrai mo rasidaand, asarhoi naturfalsafii Arastu (a. 4 to m.) ba hisob meravand (khudi istilohi «Mekhanika»-ro ba ilm Arastu jori kardaast). Asoshoi ilmii statikaro Arkhimed (a. 3 to m.) guzoshtaast. Doir ba muvozinati ashkoli hamvor yo markazhoi vazninii ashkoli hamvor «Dar borai jismhoi shinokunanda», «Maktub ba Eratosfen» nom asarhoi u ba mo dastras shudaand. Dar inkishofi minbadai statika sahmi I. Nemorariy (taqr. a. 13), Leonardo da Vinchi (a. 15), olimi gollandi Stevin (a. 16) va alalkhusus olimi fransavi P. Varinon (a. 17) kalon ast. Olimi fransavi L. Puanso nazariyai quvvahoi juftro kor kard va dar asosi on statikaro tashakkul dod (1804). Prinsiphoi asosii kinematikaro olimoni qadim Evdoksi Knidi (a. 4 to m.), Aflotun, Apolloni Pergi, Gipparkh, Batlnmus (Ptolemey), Nikomed (a. 2 to m.) va Arakhit kor kardaand. Dar asrhoi miyona ba taraqqiyoti minbadai mekhanika asosan muhaqqiqoni Mashriqzamin hissa guzoshtaand. Olimoni Shari Bann Muso, Sobit ibni Qurra, Aburayhoni Beruni, Abuabdulloh Yusufi Khorazmi, Ibni Sino, Umari Khayyom va dig. niz ba halli masalahoi gunoguni M. mashgul shudaand. Mas., yake az bobhoi kitobi duyumi («Miftokhululum» (kalidi ilmho)-i Abuabdulloh Yusufi Khorazmi (a. 10) ba Mekhanika oid ast. Sobit ibni Qurra dar «Kitob-an-ilikarastun» (kitob dar borai tarozui yakpalla) nom asarash nazariyai barkashidani moddahoro bayon kardaast. Beruni, Khayyom usulhoi muayyan kardani vazni khosi fuluzot va javohirotro kor karda baromadaand. Ibni Sino dar fasli fizikai «Donishnoma» mafhumi harakatro manidod namudaast. Modelhoi kinematikii harakati sitoraho dar risolahoi Sobit ibni Qurra, Ibni Sino va Beruni sharh yoftaand.

Asoshoi ilmii dinamika va yakjoya bo on khudi ilmi M. a. 17 ba vujud ovarda shud, zero inkishofi munosibathoi kapitalisti dar nazdi ilm talabothoi nav guzosht. Dar in soha tadqiqothoi N. Kopernik, I. Kepler, G. Galiley, R. Dekart, X. Gyuygens ahamiyati kalon doshtand, Qonunhoi asosii dinamikaro I. Nyuton (1687) tarif dod. U tadqiqothoi olimoni peshinro jambast namuda, mafhumi quvvaro umumiyat dod va dar Mekhanika mafhumi massaro jori kard. Hamin tavr, I. Nyuton asoshoi Mekhanikai klassikiro bunyod kard. Dar inkishofi minbadai Mekhanika va faslhoi judogonai on olimonu muhaqqiqoni davrhoi gunogunu mamlakathoi gunogun R. Guk, G. Leybnis, L. Eyler, G. Amonton, Sh. Kulon, I. Bernulli, L. Karno, J. Fure, J. Lagranj, J. D Alamber, P. Mopertyup, P. Laplas, M. V. Lomonosov, M. V. Ostrogradskiy, U. Gamilton, K. Yakobi, G. Gers, Grin,

S. Puasson, U. Tomson, G. Kirkhgof, O. Reynolds, L. Prandtl, N. P. Petrov, S. A. Chapligin, N. E. Jukovskiy, A. M. Lyapunov, I. A. Vishnegradskiy, I. V. Mesherskiy. K. E. Siolkovskiy va dig. sahmi bosazoe guzoshtaand. Dar zamoni hozira Mekhanika ba halli yak qator problemai muhim: nazariyai lappishho (makhsusan lappishhoi gayrikhatti), dinamikai jismi sakht, nazariyai ustuvorii harakat, Mekhanikai jismhoi massaashon tagyiryobanda va dinamikai parvozhoi kayhoni mashgul ast. Doirai masalahoi Mekhanika, inchunin tadqiqi harakati plazmaro dar maydoni magniti (gidrodinamikai magniti), yane omuzishi yake az problemahoi aktualii fizikai muosir — ba amal ovardani reaksiyai termoyadroii idorashavandaro dar bar megirad. Dar gidrodinamika halli yak qator masalaho bo problemahoi surathoi kalon dar aviasiya, ballistika, sokhtmoni turbinaho va muharrikho aloqamand ast. Hangomi hal kardani bisyor masalahoi M. kompyuterhoro samaranok istifoda burda istodaand.

Ad.: Sedov L. I., Mekhanika sploshnoe sredi. M., 1976; Grigoryan

A. T.. Mekhanika ot antichnosti do nashikh dney» M., 1971.