Yog tias koj saib cov xov hluav taws xob ze ze, koj yuav pom tias lawv nkhaus mus rau hauv qab vim yog qhov tsis sib zog. Vim li cas cov xov hluav taws xob thiaj li raug xoob, tsis yog tsuas yog nruj xwb? Feem ntau cov ru tsev hauv Flores thiab Lembata, East Nusa Tenggara, yog ua los ntawm zinc (Zn). Thaum nruab hnub lossis hmo ntuj, cov ru tsev zinc ua suab nrov. Vim li cas zinc ua suab nrov? Yog tias koj nyob ntawm kob Java, koj yuav tau pom cov kev tsheb ciav hlau. Muaj qhov sib txawv ntawm cov pob qij txha tsheb ciav hlau. Lub luag haujlwm ntawm cov qhov sib txawv no ntawm cov pob qij txha tsheb ciav hlau yog dab tsi? Muaj ntau yam koj tuaj yeem xav txog thiab nug txog kev nthuav dav.
Kev nthuav dav ntev
Feem ntau cov khoom khov kho yuav nthuav dav thaum lawv qhov kub hloov. Qhov no txhais tau tias qhov ntev nce lossis txo qis. Feem ntau, qhov ntev ntawm ib yam khoom nce ntxiv thaum nws qhov kub nce, thaum nws qhov ntev txo qis thaum nws qhov kub txo qis. Tej zaum koj yuav xav tias qhov nthuav dav tsuas yog tshwm sim hauv cov khoom xws li cov xov hlau nyias. Piv txwv li, xav txog lub tsheb nres ntawm ntug kev uas raug tshav ntuj. Thaum lub tsheb kub dhau, lub phaj hlau tuaj yeem tuab dua lossis qhov ntev ntawm nws sab tuaj yeem nce ntxiv. Lub ru tsev zinc kuj tuaj yeem muaj kev nthuav dav linear. Hauv qhov no, thaum zinc kub dhau, cov npoo ntawm zinc nthuav dav thiab zinc kuj tuaj yeem tuab dua. Tib yam tshwm sim rau txoj kev tsheb ciav hlau thiab cov choj hlau lossis hlau.
Feem ntau cov khoom khov kho nthuav dav lossis cog lus thaum lawv qhov kub hloov pauv, yog li peb yuav tsum nkag siab tias qhov kub hloov pauv cuam tshuam li cas rau qhov kev nthuav dav ntawm cov khoom khov kho. Qhov no pab tau zoo heev thaum tsim cov khoom siv, tsev, tsheb, thiab lwm yam. Piv txwv li, qhov sib txawv ntawm txoj kev tsheb ciav hlau. Txoj kev tsheb ciav hlau yog ua los ntawm hlau. Cov kws ua haujlwm tau xam qhov dav ntawm qhov sib txawv ntawm txhua txoj kev tsheb ciav hlau. Thaum hnub kub, cov tsheb ciav hlau yuav nthuav dav los ntawm ob peb centimeters. Thaum lub tsheb ciav hlau hla lawv, qhov kub ntawm cov tsheb ciav hlau kuj nce ntxiv, ua rau cov tsheb ciav hlau nthuav dav los ntawm pes tsawg centimeters. Thaum hmo ntuj txias, cov tsheb ciav hlau yuav me me los ntawm pes tsawg centimeters. Raws li kev tshuaj xyuas, cov kws ua haujlwm kwv yees qhov deb ntawm qhov sib txawv ntawm txoj kev tsheb ciav hlau kom thaum qhov kub ntawm txoj kev tsheb ciav hlau nce ntxiv, cov tsheb ciav hlau tsis kov ib leeg thiab khoov.
Yuav pab peb nrhiav tau cov mis uas qhia txog kev sib raug zoo ntawm kev hloov pauv kub thiab qhov ntau ntawm kev nthuav dav linear, xav txog ib yam khoom khov kho uas tab tom nthuav dav, raws li pom hauv daim duab sab xis. Caption: To = qhov kub pib, T = qhov kub kawg, Lo = qhov ntev pib, L = qhov ntev tom qab nthuav dav, delta L = kev hloov pauv ntawm qhov ntev, delta T = kev hloov pauv ntawm qhov kub thiab txias.
Thaum qhov kub ntawm yam khoom = T ( yam khoom tseem txias), qhov ntev ntawm yam khoom = L. Thaum qhov kub ntawm yam khoom = T (yam khoom kub nce), qhov ntev ntawm yam khoom = L. Raws li cov txiaj ntsig ntawm kev soj ntsuam thiab kev sim, qhov kev hloov pauv ntawm qhov ntev ntawm yam khoom yog proportional rau qhov kev hloov pauv ntawm qhov kub. Yog tias qhov kub nce, qhov ntev ntawm yam khoom nce. Ntawm qhov tod tes, thaum qhov kub txo qis, qhov ntev ntawm yam khoom txo qis. Qhov kev hloov pauv ntawm qhov ntev ntawm yam khoom kuj yog proportional rau qhov ntev pib ntawm yam khoom (L ) . Yog tias qhov loj ntawm qhov kev hloov pauv ntawm qhov kub zoo ib yam, piv txwv li, yam khoom uas ntev 10 meters, yuav ntev nce 2 npaug piv rau yam khoom uas ntev tsuas yog 5 meters. Yog li ntawd, qhov ntev ntawm yam khoom, qhov nthuav dav ntawm yam khoom ntau dua.
Qhov kev hloov ntawm qhov ntev ntawm ib yam khoom (delta L) yog proportional rau qhov kev hloov ntawm qhov kub thiab txias (delta T):
Qhov kev hloov pauv ntawm qhov ntev ntawm cov khoom (delta L) yog proportional rau qhov ntev pib ntawm cov khoom (Lo):
Qhov kev hloov ntawm qhov ntev ntawm txhua yam khoom yog txawv. Txawm hais tias nws loj kev hloov pauv kub Ib yam li ntawd, qhov kev nthuav dav uas hlau ntsib tsis zoo ib yam li qhov uas iav ntsib. Tib yam no muaj tseeb rau lwm yam khoom. Yog li ntawd, qhov kev nthuav dav linear nyob ntawm tus coefficient ntawm kev nthuav dav linear ntawm txhua yam khoom. Tus coefficient ntawm kev nthuav dav linear rau txhua yam khoom tau txais los ntawm kev sim. Qhov loj dua tus coefficient ntawm kev nthuav dav linear, qhov ntau dua qhov nce ntawm qhov ntev. Qhov me dua tus coefficient ntawm kev nthuav dav linear, qhov me dua qhov nce ntawm qhov ntev. Nws tuaj yeem hais tias qhov kev hloov pauv ntawm qhov ntev ntawm ib yam khoom yog proportional rau tus coefficient ntawm kev nthuav dav linear.
Peb qhov kev sib piv saum toj no tau qhia ua ib qho kev sib npaug:
Tag nrho qhov ntev ntawm ib yam khoom tom qab nthuav dav lossis nqaim tuaj yeem tau los ntawm kev ntxiv qhov ntev pib ntawm yam khoom (Lo) thiab kev hloov pauv ntawm qhov ntev ntawm yam khoom (delta L).
Thaum qhov kub hloov pauv (TT)o) yog qhov tsis zoo, ces qhov kev hloov pauv ntawm qhov ntev (LL)o) kuj tsis zoo. Hauv qhov no, qhov ntev ntawm cov khoom txo qis. Ntawm qhov tod tes, yog tias qhov kub hloov pauv (TTo) yog qhov zoo, ces qhov kev hloov pauv ntawm qhov ntev (LLo) kuj yog qhov zoo. Hauv qhov no, qhov khoom yuav ntev zuj zus.
Cov hauv qab no yog cov coefficient ntawm linear expansion ntawm cov khoom khov ntawm qhov kub ntawm 20 ° C. Cov kua thiab cov pa roj hloov pauv cov duab, tiv thaiv lawv los ntawm kev muaj kev nthuav dav linear. Cov coefficient ntawm linear expansion ntawm cov khoom khov kuj nyob ntawm qhov kub thiab txias. Ntawm qhov kub sib txawv, cov coefficient ntawm linear expansion ntawm cov khoom khov kuj sib txawv. Yog tias qhov sib txawv ntawm qhov kub tsis loj dhau, qhov sib txawv ntawm cov coefficient ntawm linear expansion kuj yuav tsis loj dhau, yog li nws tuaj yeem tsis quav ntsej.
Kev nthuav dav ntawm ntim
Tsuas yog cov khoom khov kho thiaj li nthuav qhov ntev xwb, txhua yam khoom, txawm tias khov kho, kua los yog roj, kuj nthuav qhov ntim tau thiab. Cov qauv rau kev nthuav qhov ntim zoo ib yam li cov qauv rau kev nthuav qhov ntev.
Tus qauv kev nthuav dav ntawm qhov ntim saum toj no tsuas yog siv tau thaum qhov kev hloov pauv ntawm qhov ntim ntawm ib yam khoom (txawm tias khoom khov, kua, lossis roj) me dua qhov ntim pib ntawm yam khoom. Yog tias qhov kev hloov pauv ntawm qhov ntim ntawm ib yam khoom loj dua qhov ntim pib ntawm yam khoom, tus qauv kev nthuav dav ntawm qhov ntim tsis muab cov txiaj ntsig tseeb. Feem ntau qhov kev hloov pauv ntawm qhov ntim uas cov khoom khov ntsib tsis loj dhau. Qhov sib piv, tus nqi ntawm cov kua thiab cov pa roj loj heev. Tus nqi ntawm cov pa roj kuj yooj yim hloov pauv nrog qhov kev hloov pauv ntawm qhov kub thiab txias. Yog li ntawd, tus qauv saum toj no tsuas yog siv rau kev nthuav dav ntawm cov khoom khov. Tus qauv rau kev txiav txim siab qhov kev hloov pauv ntawm qhov ntim roj yuav raug kawm hauv lub ncauj lus ntawm txoj kev xav ntawm cov pa roj hauv qib 11.
