Feem ntau cov khoom khov kho muaj kev nthuav dav linear thaum qhov kub hloov pauv. Qhov kev nthuav dav linear yog qhov ntev ntawm cov khoom nce lossis qhov ntev ntawm cov khoom txo qis. Feem ntau, qhov ntev ntawm cov khoom nce thaum qhov kub nce, thaum qhov ntev ntawm cov khoom txo qis thaum qhov kub poob qis. Tej zaum koj yuav xav tias kev nthuav dav linear tsuas yog tshwm sim ntawm cov khoom xws li cov xov hlau nyias. Piv txwv li, saib lub tsheb uas nres ntawm ntug kev, yog li nws raug tshav ntuj. Thaum lub tsheb kub dhau, lub phaj hlau tuaj yeem tuab dua, lossis qhov ntev ntawm sab tuaj yeem nce. Cov ru tsev ntawm cov tsev ua los ntawm zinc kuj tuaj yeem nthuav dav. Hauv qhov no, thaum zinc kub dhau, cov npoo ntawm zinc nce dav thiab zinc tuaj yeem tuab dua. Tib yam tau tshwm sim rau txoj kev tsheb ciav hlau thiab hlau lossis hlau ntawm tus choj.
Feem ntau cov khoom khov kho nthuav dav lossis ntsws thaum qhov kub ntawm cov khoom hloov pauv, yog li peb yuav tsum paub tias qhov kub hloov pauv cuam tshuam li cas rau qhov nthuav dav ntawm cov khoom khov kho. 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, txoj kev tsheb ciav hlau yuav nthuav dav ob peb centimeters. Thaum lub tsheb ciav hlau hla dhau, qhov kub ntawm txoj kev tsheb ciav hlau kuj nce ntxiv kom txoj kev tsheb ciav hlau nthuav dav mus rau pes tsawg centimeters. Thaum hmo ntuj txias, txoj kev tsheb ciav hlau ntsws mus rau pes tsawg centimeters.
Raws li cov txiaj ntsig ntawm kev tshuaj xyuas, cov engineers kwv yees qhov deb ntawm cov qhov sib txawv ntawm txoj kev tsheb ciav hlau, yog li thaum qhov kub ntawm txoj kev tsheb ciav hlau nce ntxiv, cov txoj kev tsheb ciav hlau yuav tsis sib chwv thiab khoov.
Yuav pab peb nrhiav tau ib daim qauv uas qhia txog kev sib raug zoo ntawm kev hloov pauv ntawm qhov kub thiab qhov loj ntawm kev nthuav dav, saib xyuas ib yam khoom khov kho uas tab tom nthuav dav, raws li pom hauv daim duab hauv qab no.
To = qhov kub pib, T = qhov kub kawg, Lo = qhov ntev pib, ΔL = kev hloov pauv ntawm qhov ntev, L = qhov ntev tom qab nthuav dav, ΔT = kev hloov pauv ntawm qhov kub thiab txias.
Thaum qhov kub ntawm yam khoom = To (yam khoom tseem txias), qhov ntev ntawm yam khoom = Lo. Thaum qhov kub ntawm yam khoom = T (qhov kub ntawm yam khoom nce ntxiv), 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 cov khoom yog proportional rau qhov kev hloov pauv ntawm qhov kub thiab txias. Yog tias qhov kub thiab txias nce, qhov ntev ntawm cov khoom nce. Ntawm qhov tod tes, thaum qhov kub thiab txias txo qis, qhov ntev ntawm cov khoom txo qis. Qhov kev hloov pauv ntawm qhov ntev ntawm ib yam khoom kuj yog proportional rau qhov ntev ntawm cov khoom qub (Lo). Yog tias qhov kub thiab txias hloov pauv zoo ib yam, cov khoom uas ntev 10 meters, piv txwv li, yuav ntev ob npaug piv rau cov khoom uas tsuas yog 5 meters ntev. Yog li, qhov ntev ntawm cov khoom, qhov dav ntawm cov khoom.
Kev hloov ntawm qhov ntev ntawm yam khoom (L) yog sib npaug rau kev hloov ntawm qhov kub thiab txias (ΔT): ΔL α ΔT
Kev hloov pauv ntawm qhov ntev ntawm ib yam khoom (ΔL) yog proportional rau qhov ntev ntawm yam khoom qub (Lo): ΔL α Lo
Kev hloov ntawm qhov ntev ntawm txhua yam khoom sib txawv. Txawm hais tias qhov kub hloov pauv zoo ib yam, qhov kev nthuav dav uas hlau ntsib tsis zoo ib yam li iav. Ib yam li ntawd nrog lwm yam khoom. Yog li, qhov kev nthuav dav linear nyob ntawm tus coefficient ntawm kev nthuav dav linear ntawm txhua yam khoom. Qhov loj dua tus coefficient ntawm kev nthuav dav linear, qhov ntev nce ntau dua. Qhov me dua tus coefficient ntawm kev nthuav dav linear, qhov ntev nce me dua. 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.
∆L ∝ α
Peb qhov kev sib piv saum toj no tau qhia ua ib qho kev sib npaug:
Kev piav qhia: ΔL = Qhov kev hloov pauv ntawm qhov ntev, α = Tus coefficient ntawm linear expansion (units α = K)-1 los yog (Co)-1, Lo = Qhov ntev pib, ΔT (T1 - To) ΔT = Kev hloov pauv ntawm qhov kub thiab txias (qhov kub kawg - qhov kub pib)
Tag nrho qhov ntev ntawm ib yam khoom tom qab muaj kev nthuav dav lossis ntsws tuaj yeem tau los ntawm kev ntxiv qhov ntev pib ntawm yam khoom (Lo) thiab qhov kev hloov pauv ntawm qhov ntev ntawm cov khoom (ΔL).
Kev piav qhia: ΔL = qhov ntev ntawm cov khoom tom qab nthuav dav lossis ntsws, Lo = Qhov ntev pib ntawm yam khoom, ΔL = L – Lo = Qhov kev hloov pauv ntawm qhov ntev, α = Tus coefficient ntawm linear expansion (units ntawm α = K-1 los yog (Co)-1, ΔT = T – To = Kev hloov pauv kub, To = Qhov kub pib, T = qhov kub kawg.
Yog tias qhov kub hloov pauv (TTo) yog qhov tsis zoo, ces qhov kev hloov pauv ntawm qhov ntev (LLo) kuj tsis zoo thiab.
Hauv qhov no, qhov ntev ntawm cov khoom txo qis. conversely, 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, cov khoom ntev zuj zus.
Hauv qab no yog tus nqi ntawm cov coefficient ntawm linear expansion ntawm cov khoom khov, ntawm qhov kub ntawm 20 ° C. Cov duab ntawm cov kua thiab cov pa roj hloov pauv kom ob hom tshuaj no tsis tuaj yeem ntsib qhov linear expansion. 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 tseem ceeb heev, qhov sib txawv ntawm cov coefficient ntawm linear expansion tsis tseem ceeb heev kom nws tsis tuaj yeem tsis quav ntsej.
