5 piv txwv ntawm cov lus nug nthuav dav
1. Ib lub pob khov kho yog ua los ntawm txhuas nrog tus coefficient ntawm linear expansion ntawm 24 x 10-6 oC-1. Yog tias qhov kub yog 30oC lub pob loj li 30 cm3 yog li ntawd qhov ntim ntawm lub pob nce mus txog 30,5 cm3, Lub pob yuav tsum tau ua kom sov kom txog thaum nws kub txog li ntawm….. oC
Kev Sib Tham
Nws paub tias:
Tus coefficient ntawm linear expansion (α)) = 24 x 10-6 oC-1
Volume expansion coefficient (γ= 3 TZS ib = 3 x 24 x 10-6 oC-1 Luas = 72 x 10-6 oC-1
Kub pib (T1= 30 TZSoC
Qhov ntim pib (V1) = 30 cm3
Qhov ntim kawg (V2) = 30,5 cm3
Kev hloov pauv ntawm qhov ntim (Δ)V) = 30,5 cm3 - 30 cm3 Luas = 0,5 cm3
Nug: Qhov kub kawg (T2)
Lus teb:
ΔV = g (V1)(ΔT)
ΔV = g (V1)(T2 - T1)
0,5 cm3 = (72 x 10-6 oC-1)(30 cm3)(T2 - 30oC)
0,5 = (2160 X XUM-6)(T2 - 30)
0,5 = (2,160 X XUM-3)(T2 - 30)
0,5 = (2,160 X XUM-3)(T2 - 30)
0,5 / (2,160 X XUM-3) = T2 - 30
0,23 x 103 = T ua2 - 30
0,23 x 1000 = T2 - 30
230 = T2 - 30
230 + 30 = T2
T2 = 260oC
2. Ib lub pob iav uas khoob muaj tus coefficient ntawm kev nthuav dav linear ntawm 9 x 10-6 oC-1. Thaum kub txog 20oC lub cheeb sab hauv ntawm lub pob yog 2,2 cm. Yog tias lub pob sab hauv txoj kab uas hla nce mus txog 2,8 ces suhu qhov kawg yog….
Kev Sib Tham
Nws paub tias:
Tus coefficient ntawm linear expansion (α)) = 9 x 10-6 oC-1
Volume expansion coefficient (γ) = 3 α = 3 x 9 x 10-6 oC-1 Luas = 27 x 10-6 oC-1
Kub pib (T1= 20 TZSoC
Txoj kab uas hla pib (D1) = 2,2 cm
Qhov kawg txoj kab uas hla (D2) = 2,8 cm
Lub vojvoog pib (r)1) = D1 / 2 = 2,2 cm3 / 2 = 1,1 cm3
Qhov kawg radius (r)2) = D2 / 2 = 2,8 cm3 / 2 = 1,4 cm3
Qhov ntim pib (V1) = 4/3 π r13 = (4/3)(3,14)(1,1 cm)3 = (4/3)(3,14)(1,331 cm)3) = 5,57 cm3
Qhov ntim kawg (V2) = 4/3 π r23 = (4/3)(3,14)(1,4 cm)3 = (4/3)(3,14)(2,744 cm)3) = 11,48 cm3
Kev hloov pauv ntawm qhov ntim (Δ)V) = 11,48 cm3 - 5,57 cm3 Luas = 5,91 cm3
Nug: Qhov kub kawg (T2)
Lus teb:
ΔV = g (V1)(ΔT)
5,91 cm3 = (27 x 10-6 oC-1)(5,57 cm3)(T2 - 20oC)
5,91 = (150,39 X XUM-6)(T2 - 20)
5,91/150,39 x 10-6 = T ua2 - 20
0,039 x 106 = T ua2 - 20
39 x 103 = T ua2 - 20
39000 = T2 - 20
T2 = 39020oC
3. Thaum cua sov, qhov nce ntawm qhov ntim yog proportional rau ...
A. Qhov kub pib
B. Qhov kub kawg
C. Kub nce ntxiv
D. Lub ntim pib
E. Phau ntawv kawg
Kev Sib Tham:
Qhov nce ntawm qhov ntim cua yog sib npaug rau qhov nce ntawm qhov kub thiab txias lossis kev hloov pauv ntawm qhov kub thiab txias. Qhov kub nce ntau npaum li cas, qhov ntim ntxiv ntau npaum li ntawd.
4. Ib lub thawv iav 4 liv puv nrog dej, tom qab ntawd cua sov kom qhov kub nce mus txog 20 degrees.oC. Nws hloov tawm tias muaj qee cov dej nchuav. Tus coefficient ntawm linear expansion ntawm iav yog paub tias yog 9 x 10-6 oC-1; tus coefficient ntawm kev nthuav dav ntawm cov dej = 2,1 x 10-4 oC-1, ces qhov dej uas nchuav yog ...
A. 0,015 liv
B. 0,018 liv
C. 0,020 liv
D. 0,021 liv
E. 0,025 liv
Kev Sib Tham
Nws paub tias:
Qhov ntim pib ntawm lub khob iav thiab dej (V)o) = 4 liv
Kev hloov pauv ntawm qhov kub ntawm iav thiab dej (ΔT) = 20oC
Tus coefficient ntawm linear expansion ntawm iav (α) = 9 x 10-6 oC-1
Cov coefficient ntawm qhov nthuav dav ntawm cov iav (γ) = 3α = 3 (9 x 10-6 oC-1) = 27 x 10-6 oC-1
Tus coefficient ntawm kev nthuav dav ntawm dej (γ) Luas = 2,1 x 10-4 oC-1
Nug: Bdej ntau dhau
Lus teb:
Cov mis ntawm kev nthuav dav ntim:
V = Vo + γ Vo T
V - Vo = γ Vo T
ΔV = γ Vo T
Cov Ntaub Ntawv:
V = qhov ntim kawg, Vo = qhov ntim pib, ΔV = kev hloov pauv ntawm qhov ntim, γ = coefficient ntawm kev nthuav dav ntim, ΔT = kev hloov pauv ntawm qhov kub thiab txias.
Xam qhov kev hloov pauv ntawm qhov ntim ntawm lub khob iav:
ΔV = γ Vo ΔT = (27 x 10-6)(4)(20) = 2160 x 10-6 Luas = 2,160 x 10-3 = 0,002160 liv
Xam qhov kev hloov pauv ntawm cov dej ntim:
ΔV = γ Vo ΔT = (2,1 x 10-4)(4)(20) = 168 x 10-4 = 0,0168 liv
Qhov kev hloov pauv ntawm cov dej ntim ntau dua li lub khob iav yog li qee qhov dej nchuav.
Xam qhov ntim ntawm cov dej uas nchuav tawm:
0,0168 liter - 0,002160 liter = 0,01464 liter = 0,015 hli
Cov lus teb yog lawm yog A.
5. Ib lub nkoj ua los ntawm hlau (coefficient ntawm linear expansion = 10-5 oC-1) muaj qhov loj ntawm 6 liv uas muaj acetone kua (qhov ntim nthuav dav coefficient = 1,5 x 10-3 oC-1). Yog tias ob qho tib si raug cua sov kom qhov kub ntawm chav tsev nce ntawm 0oC txog 40oC, ces qhov ntim ntawm acetone nchuav yog ...
A. 0,35 liv
B. 0,48 liv
C. 0,58 liv
D. 1,36 liv
E. 1,48 liv
Kev Sib Tham
Nws paub tias:
Qhov ntim pib ntawm cov hlau thiab acetone thawv (Vo) = 6 liv
Kev hloov pauv ntawm qhov kub ntawm lub thawv hlau thiab acetone (ΔT) = 40oC
Coefficient ntawm linear expansion ntawm hlau (α) = 10-5 oC-1
Coefficient ntawm qhov ntim nthuav dav ntawm hlau (γ) = 3α = 3 (10-5 oC-1) = 3 x 10-5 oC-1
Cov coefficient ntawm kev nthuav dav ntawm acetone (γ) = 1,5 x 10-3 oC-1
Nug: Bdej ntau dhau
Lus teb:
Cov mis ntawm kev nthuav dav ntim:
ΔV = γ Vo T
Cov Ntaub Ntawv:
ΔV = kev hloov pauv ntawm qhov ntim, γ = coefficient ntawm kev nthuav dav ntim, Vo = qhov ntim pib, ΔT = kev hloov pauv ntawm qhov kub thiab txias.
Xam qhov kev hloov pauv ntawm qhov ntim ntawm lub nkoj hlau:
ΔV = γ Vo ΔT = (3 x 10-5)(6)(40) = 720 x 10-5 = 0,00720 liv
Xav txog qhov kev hloov pauv ntawm qhov ntim ntawm acetone:
ΔV = γ Vo ΔT = (1,5 x 10-3)(6)(40) = 360 x 10-3 = 0,360 liv
Qhov kev hloov pauv ntawm acetone ntau dua li ntawm lub thawv hlau yog li qee cov dej ntws tawm.
Xam qhov ntim ntawm cov dej uas nchuav tawm:
0,360 liter - 0,00720 liter = 0,3528 liter = 0,35 hli
Cov lus teb yog lawm yog A.
