9 Piv Txwv ntawm Cov Lus Nug Txog Kev Nthuav Dav
1. Ib daim hlau uas kub txog 20 o C muaj qhov ntev li qhia hauv daim duab. Yog tias tus coefficient ntawm linear expansion ntawm hlau yog 10 -5 o C -1, ces qhov nce ntawm thaj chaw ntawm kub txog 60 o C yog...
A. 0,08 cm2
B. 0,16 cm 2
C. 0,24 cm 2
D. 0,36 cm 2
E. 0,64 cm 2
Kev Sib Tham
Nws yog paub tias :
Hlau ntev = 40 cm
Hlau dav = 20 cm
Thaj chaw hlau pib (A o ) = (40)(20) = 800 cm 2
Tus coefficient ntawm linear expansion (α) ntawm hlau = 10 -5 o C -1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 2 x 10 -5 o C -1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 60 o C – 20 o C = 40 o C
Lo lus nug : Kev nce hauv thaj chaw ntawm cov hlau ntawm qhov kub ntawm 60 o C
Lus teb :
Cov qauv nthuav dav ntawm thaj chaw :
ΔA = βA o ΔT
Kev piav qhia txog cov mis:
ΔA = nce thaj tsam, β = tus coefficient ntawm thaj tsam nthuav dav, A o = thaj tsam pib, ΔT = kev hloov pauv ntawm qhov kub = qhov kub kawg - qhov kub pib
Kev nce ntxiv ntawm thaj chaw hlau :
ΔA = βA o ΔT
Luas = 2 x 10 - 5 (800) (40) = 0,64 cm
Cov lus teb yog yog E.
2. Ib lub phaj hlau uas muaj qhov kub ntawm 20 o C muaj qhov ntev raws li qhia hauv daim duab. Yog tias qhov kub nce mus txog 100 o C thiab tus coefficient ntawm kev nthuav dav ntawm hlau yog 1,1 x 10 -7 o C -1 , ces nws thaj chaw tam sim no yuav yog ...
A. 4,0000106 m2
B. 4,0000140 m 2
C. 4,0000376 m 2
D. 4,0000704 m 2
E. 4,0000726 m 2
Kev Sib Tham
Nws yog paub tias :
Ntev ntawm hlau = 2 m
Hlau dav = 2 m
Thaj chaw pib ntawm hlau (Ao ) = (2)(2) = 4 m2
Tus coefficient ntawm linear expansion (α) ntawm hlau = 1,1 x 10 -7 o C -1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 2,2 x 10 -7 o C -1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 100 o C – 20 o C = 80 o C
Lo lus nug : Thaj chaw ntawm hlau ntawm qhov kub ntawm 100 o C
Lus teb :
Kev nce ntxiv ntawm thaj chaw hlau :
ΔA = βA o ΔT
ΔA = (2,2 x 10 -7 )(4)(80) = 704 x 10 -7 = 0,0000704 m2
Thaj chaw hlau :
Thaj chaw ntawm hlau = thaj chaw pib + thaj chaw nce ntxiv
Thaj chaw ntawm hlau = 4 m 2 + 0,0000704 m 2
Thaj chaw ntawm hlau = 4,0000704 m 2
Cov lus teb yog D.
3. Ib lub phaj ua los ntawm tooj dag (α = 18.10 -6 o C -1 ) ntawm qhov kub ntawm 0 o C muaj qhov ntev raws li pom hauv daim duab. Yog tias lub phaj raug cua sov rau 80 o C, ces qhov nce hauv thaj chaw ntawm lub phaj yog ...
A. 0,576.10-4 m2
B. 1,152.10 -4 m 2
C. 2,304.10 -4 m 2
D. 3,456.10 -4 m 2
E. 4,608.10 -4 m 2
Kev Sib Tham
Nws yog paub tias :
Qhov ntev ntawm tooj dag = 40 cm = 0,4 meters
Qhov dav ntawm tooj liab = 20 cm = 0,2 meters
Thaj chaw pib ntawm tooj dag (Ao ) = (0,4)(0,2) = 0,08 m2
Tus coefficient ntawm linear expansion (α) ntawm tooj dag = 18 x 10 -6 o C -1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 36 x 10 -6 o C -1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 80 o C – 0 o C = 80 o C
Lo lus nug : Kev nce hauv thaj chaw ntawm tooj liab ntawm qhov kub ntawm 80 o C
Lus teb :
Kev nce ntawm thaj chaw tooj liab :
ΔA = βA o ΔT
ΔA = (36 x 10 -6 ) (0,08)(80) = 230,4 x 10 -6 = 2,304 x 10 -4 m2
Cov lus teb yog C.
4. Lub thawv txhuas 2000 cm3, puv nrog dej ntawm qhov kub pib ntawm 0oC. Tom qab ntawd lub nkoj raug cua sov kom txog thaum qhov kub yog 90oC. Yog tias tus coefficient ntawm linear expansion ntawm txhuas yog 24 x 10-6 (oC)-1 thiab tus coefficient ntawm qhov ntim nthuav dav ntawm dej yog 6,3 x 10-4 (oC)-1, qhov ntim ntawm cov dej uas nchuav yog….
A. 100,94 cm 3
B. 100,84 cm 3
C. 100,64 cm 3
D. 100,54 cm 3
E. 100,44 cm 3
Kev Sib Tham
Nws paub tias:
Qhov ntim pib ntawm lub thawv txhuas thiab dej (Vo ) = 2000 cm3 = 2 x 10 3 cm3
Qhov kub pib ntawm lub thawv txhuas thiab dej (T1 ) = 0 o C
Qhov kub kawg ntawm lub thawv txhuas thiab dej (T2 ) = 90 o C
Tus coefficient ntawm linear expansion ntawm txhuas (α) = 24 x 10 -6 ( oC ) -1
Coefficient ntawm qhov ntim nthuav dav ntawm txhuas ( γ) = 3α = 3 (24 x 10 -6 ( oC ) -1 ) = 72 x 10 -6 oC -1
Cov coefficient ntawm kev nthuav dav ntawm dej (γ) = 6,3 x 10 -4 ( oC ) -1
Lus Nug: Qhov ntim ntawm cov dej nchuav
Lus teb:
Cov mis ntawm kev nthuav dav ntim:
V = V₂O + γ V₂O ΔT
V – Vo = γ Vo ΔT
ΔV = γ V o ΔT
Cov Ntaub Ntawv:
V = qhov ntim kawg, V = qhov ntim pib, ΔV = kev hloov pauv ntawm qhov ntim, γ = tus coefficient ntawm kev nthuav dav ntawm qhov ntim, ΔT = kev hloov pauv ntawm qhov kub thiab txias.
Xam qhov kev hloov pauv ntawm qhov ntim ntawm lub thawv txhuas:
ΔV = γ V o ΔT = (72 x 10 -6 )(2 x 10 3 )(90) = 12960 x 10 -3 = 12,960 cm 3
Xam qhov kev hloov pauv ntawm cov dej ntim:
ΔV = γ V o ΔT = (6 .3 x 10 -4 )(2 x 10 3 )(90) = 1134 x 10 -1 = 113,4 cm 3
Qhov kev hloov pauv ntawm cov dej ntim ntau dua li lub thawv txhuas yog li qee qhov dej nchuav.
Xam qhov ntim ntawm cov dej uas nchuav tawm:
113,4 cm 3 – 12,960 cm 3 = 100,44 cm 3
Cov lus teb yog yog E.
5. Ib daim hlau raug cua sov kom kub txog 80 o C thiab nws qhov ntev dhau los ua 115 cm. Yog tias tus coefficient ntawm linear expansion ntawm cov hlau yog 3.10 -3 o C -1 thiab qhov kub pib ntawm cov hlau yog 30 o C, ces qhov ntev pib ntawm cov hlau yog….
A. 100 cm
B. 101,5 cm
C. 102 cm
D. 102,5 cm
E. 103 cm
Kev Sib Tham
Nws paub tias:
Kub pib (T1= 30 TZSoC
Qhov kub kawg (T2= 80 TZSoC
Kev hloov pauv kub (ΔT) = 80oC - 30oC = 50oC
Tus coefficient ntawm linear expansion ntawm hlau (α) = 3.10-3 oC-1
Qhov ntev kawg ntawm cov hlau (L) = 115 cm
Yuav tsum muaj: Qhov ntev pib ntawm cov hlau (L)o)
Lus teb:
Cov mis ntev nthuav dav:
L = Lo + ΔL
L = Lo + α Lo T
L = Lo (1 + α ΔT)
115 = Lo (1 + (3.10)-3.50) )
115 = Lo (1 + (150.10)-3))
115 = Lo (1 + 0,15)
115 = Lo (1,15)
Lo = 115/1,15
Lo Luas = 100 cm
Cov lus teb yog lawm yog A.
6. Ib tug pas nrig tooj liab pib ntev li 40 cm. Thaum cua sov ntawm qhov kub ntawm 80 o C nws qhov ntev yuav dhau los ua 40,04 cm. Yog tias tus coefficient ntawm linear expansion ntawm tooj liab yog 2,0 x 10 -5 o C -1 ces qhov kub pib ntawm tus pas nrig tooj liab yog….
A. 20 oC
B. 22 oC
C. 25 oC
D. 30 oC
E. 50 oC
Kev Sib Tham
Nws paub tias:
Qhov kub kawg (T2= 80 TZSoC
Qhov ntev pib (Lo) = 40 cm
Qhov ntev kawg (L) = 40,04 cm
Kev nce ntxiv ntawm qhov ntev (ΔL) = 40,04 cm - 40 cm = 0,04 cm
Tus coefficient ntawm linear expansion ntawm tooj dag (α) = 2,0 x 10-5 oC-1
Nug: Qhov kub pib (T1)
Lus teb:
Cov mis ntawm kev nthuav dav hlau:
L = Lo + α Lo T
L – Lo = α Lo T
ΔL = αLo T
ΔL = αLo (T2 - T1)
0,04 = (2,0 x 10-5)(40)(80 – T1)
0,04 = (80 x 10-5)(80 – T1)
0,04 = 0,0008 (80 – T1)
0,04 = 0,064 – 0,0008 T1
0,0008 T1 = 0,064-0,040
0,0008 T1 = 0,024
T1 = 30oC
Cov lus teb yog D.
7. Ib daim hlau ntawm qhov kub ntawm 20oC muaj qhov ntev raws li pom hauv daim duab. Yog tias tus coefficient ntawm linear expansion ntawm hlau yog 10-5 oC-1 ces qhov nce ntxiv ntawm thaj chaw ntawm qhov kub ntawm 60oC yog…
A. 0,08 cm2
B. 0,16 cm2
C. 0,24 cm2
D. 0,36 cm2
E. 0,64 cm2
Kev Sib Tham
Lo lus nug no muaj feem cuam tshuam nrog kev nthuav dav.
Nws yog paub :
Hlau ntev = 40 cm
Hlau dav = 20 cm
Thaj chaw hlau pib (Ao) = (40)(20) = 800 cm2
Tus coefficient ntawm linear expansion (α) ntawm hlau = 10-5 oC-1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 2 x 10-5 oC-1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 60oC - 20oC = 40oC
Nug : Kev nce ntxiv ntawm thaj chaw ntawm cov hlau ntawm qhov kub thiab txias 60oC
Jawb :
Cov qauv nthuav dav ntawm thaj chaw :
ΔA = βAo T
Kev piav qhia txog cov mis:
ΔA = nce thaj tsam, β = coefficient ntawm thaj tsam nthuav dav, Ao = thaj chaw pib, ΔT = kev hloov pauv ntawm qhov kub = qhov kub kawg - qhov kub pib
Kev nce ntxiv ntawm thaj chaw hlau :
ΔA = βAo T
ΔA = (2 x 10-5)(800)(40) = 0,64 cm
Cov lus teb yog yog E.
8. Phaj hlau ntawm qhov kub ntawm 20oC muaj qhov ntev raws li pom hauv daim duab. Yog tias suhunws tau nce mus txog 100oC thiab tus coefficient ntawm linear expansion ntawm hlau yog 1,1 x 10-7 oC-1, ces thaj chaw tam sim no dhau los ua ...
A. 4,0000106 m2
B. 4,0000140 m2
C. 4,0000376 m2
D. 4,0000704 m2
E. 4,0000726 m2
Kev Sib Tham
Nws yog paub :
Ntev ntawm hlau = 2 m
Hlau dav = 2 m
Thaj chaw pib ntawm hlau (Ao) = (2)(2) = 4 m2
Tus coefficient ntawm linear expansion (α) ntawm hlau = 1,1 x 10-7 oC-1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 2,2 x 10-7 oC-1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 100oC - 20oC = 80oC
Nug : Thaj chaw ntawm hlau ntawm qhov kub ntawm 100oC
Jawb :
Kev nce ntxiv ntawm thaj chaw hlau :
ΔA = βAo T
ΔA = (2,2 x 10-7)(4)(80) = 704 x 10-7 = 0,0000704 m2
Thaj chaw hlau :
Thaj chaw ntawm hlau = thaj chaw pib + thaj chaw nce ntxiv
Thaj tsam ntawm hlau = 4 m2 + 0,0000704 m2
Thaj tsam ntawm hlau = 4,0000704 m2
Cov lus teb yog D.
9. Ib lub phaj yog ua los ntawm tooj dag (α = 18.10-6 oC-1) ntawm qhov kub ntawm 0oC muaj qhov loj raws li qhia hauv daim duab. Yog tias lub phaj raug cua sov rau 80 oC, ces qhov nce ntawm thaj tsam ntawm lub phaj yog...
A. 0,576.10-4 m2
B. 1,152.10-4 m2
C. 2,304.10-4 m2
D. 3,456.10-4 m2
E. 4,608.10-4 m2
Kev Sib Tham
Nws yog paub :
Qhov ntev ntawm tooj dag = 40 cm = 0,4 meters
Qhov dav ntawm tooj liab = 20 cm = 0,2 meters
Thaj chaw tooj liab pib (Ao) = (0,4)(0,2) = 0,08 m2
Tus coefficient ntawm linear expansion (α) ntawm tooj dag = 18 x 10-6 oC-1
Tus coefficient ntawm thaj chaw nthuav dav (β) = 2 x tus coefficient ntawm qhov ntev nthuav dav (2α) = 36 x 10-6 oC-1
Qhov sib txawv ntawm qhov kub thiab txias (ΔT) = 80oC - 0oC = 80oC
Nug : Nce thaj tsam ntawm tooj liab ntawm qhov kub ntawm 80oC
Jawb :
Kev nce ntawm thaj chaw tooj liab :
ΔA = βAo T
ΔA = (36 x 10-6)(0,08)(80) = 230,4 x 10-6 Luas = 2,304 x 10-4 m2
Cov lus teb yog C.
Qhov chaw nug lus:
Cov Lus Nug Txog Kev Xeem Physics Hauv Tebchaws Rau Tsev Kawm Ntawv Theem Siab/Tsev Kawm Ntawv Theem Siab Ua Haujlwm
