9 Qhov Kub Qhov Loj Qhov kub tshwj xeeb Qhov kev hloov pauv ntawm qhov kub thiab txias - Teeb Meem thiab Kev Dais Teeb Meem
1. Ib tug 2 kg lead yog cua sov los ntawm 50oC rau 100oC. Tus lub tshav kub tshwj xeeb ntawm cov hlau lead yog 130 J.kg-1 oC-1. Npaum licas Thaum tshav kub kub puas yog cov hlau lead nqus tau?
Paub:
Qhov hnyav (m) = 2 kg
Qhov kub tshwj xeeb (c) = 1 3 0 J.kg -1 C -1
Qhov kev hloov pauv ntawm qhov kub thiab txias ( Δ T) = 100 o C – 50 o C = 50 o C
Xav tau: Kub (Q)
Tshuaj:
Q = mc Δ T
Q = cua sov , m = pawg, c = cua sov tshwj xeeb , Δ T = kev hloov pauv ntawm qhov kub thiab txias
Cov cua sov uas cov hlau lead nqus tau:
Q = (2 kg)(1 3 0 J.kg -1 C -1 )(50 o C)
Q = (100)(1 3 0)
Q = 1 3,000 Joules
Q = 1.3 x 104 Joules
[irp]
2. Lub cua sov tshwj xeeb ntawm tooj liab yog 390 J/k g o C, qhov kev hloov pauv ntawm qhov kub thiab txias yog 40 o C. Yog tias tooj liab nqus tau 40 Joules ntawm cua sov, qhov hnyav ntawm tooj liab yog dab tsi!
Paub:
Lub cua sov tshwj xeeb ntawm tooj liab (c) = 390 J/ kg o C
Qhov kev hloov pauv ntawm qhov kub thiab txias ( ΔT ) = 40 o C
Kub ( Q) = 40 J
Xav tau: Qhov hnyav (m) ntawm tooj liab
Tshuaj:
Q = mc Δ T
40 J = (m)( 390 J/k g o C)(40 o C)
40 = (m)( 390 /kg )(40)
40 = (m)( 390 /kg )(4)
40 = (m)( 1560 /kg )
m = 40 / 1560
m = 0.026 kg
m = 26 grams
3. Qhov kub pib ntawm 20 grams dej yog 30 o C. Qhov kub tshwj xeeb ntawm dej yog 1 cal g -1 o C -1 . Yog tias dej nqus tau 300 calories ntawm qhov kub, txiav txim siab qhov kub kawg!
Paub:
Qhov hnyav (m) = 20 gr
Qhov kub pib (T 1 ) = 30 o C
Qhov kub tshwj xeeb ntawm dej (c) = 1 cal gr -1 o C -1
Kub (Q) = 300 calorie
Xav tau: Qhov kub kawg ntawm dej
Tshuaj:
Q = mc ΔT
300 calories = (20 gr)( 1 calories gr -1 o C -1 )( T 2 -30 )
300 = (20)(1)( T 2 -30)
300 = 20 ( T 2 -30 )
300 = 20 T 2 – 600
300 + 600 = 20T 2
900 = 20T 2
T 2 = 900 / 20
T 2 = 45
Qhov kev hloov pauv ntawm qhov kub thiab txias yog 45 o C – 30 o C = 15 o C.
[irp]
4. Tqhov kev hloov pauv ntawm qhov kub thiab txias ntawm dej hiav txwv is 1oC thaum dej nqus tau 3900 Joules ntawm cua sov. Lub cua sov tshwj xeeb ntawm dej hiav txwv yog 3.9 × 103 J/kg°C, qhov loj ntawm dej hiav txwv yog dab tsi.
Paub:
Qhov kev hloov pauv ntawm qhov kub thiab txias ( ΔT ) = 1 o C
Kub (Q) = 3900 Joule
Qhov kub tshwj xeeb ntawm dej hiav txwv (c) = 3.9 x 10 3 J/ k g°C = 3900 J/Kg°C
Qhov Loj: (m)
Tshuaj:
Q = mc Δ T
Q = cua sov , m = pawg, c = cua sov tshwj xeeb , Δ T = qhov hloov pauv ntawm qhov kub thiab txias
m = Q / c Δ T = 3900 / (3900)(1) = 3900 / 3900 = 1 kg
5. Ib lub tooj liab hnyav 2-kg nqus tau 39,000 J ntawm cua sov ntawm 30°C. Yog tias qhov cua sov tshwj xeeb ntawm tooj liab yog 390 J/kg °C, qhov kub kawg ntawm tooj liab yog dab tsi …
Paub:
Qhov hnyav (m) = 2 kg
Kub pib (T1 ) = 30 o C
Kub (Q) = 39,000 Joule
Cov cua sov tshwj xeeb (c) ntawm tooj liab = 390 J/kg o C
Xav tau : Qhov kub kawg (T 2 )
Tshuaj:
Q = mc ΔT
Q = cua sov , m = pawg, c = cua sov tshwj xeeb , ΔT = qhov hloov pauv ntawm qhov kub thiab txias
Q = mc ΔT = mc ( T2 – T1 )
39,000 = (2)( 390)(T 2 – 30)
100 = (2)(1)(T 2 – 30)
100 = (2)(T 2 – 30)
50 = T 2 – 30
T 2 = 50 + 30
T2 = 80 oC
[irp]
6. Ib dej hnyav 5 kg raug cua sov ntawm 15°C mus txog 40°C. Dej nqus cua sov npaum li cas. Qhov kub tshwj xeeb ntawm dej yog 4.2 × 10 3 J/Kg° C.
Paub:
Qhov hnyav (m) = 5 kg
Kub pib (T 1 ) = 15°C
Qhov kub kawg (T 2 ) = 40°C
Qhov kub tshwj xeeb ntawm dej (c) = 4.2 × 10 3 J/kg° C
Xav tau: Kub (Q)
Tshuaj:
Q = mc ΔT
Q = (5 kg)( 4.2 × 10 3 J/kg°C)(40°C – 15°C)
Q = (5)( 4.2 × 10 3 J)(25)
Q = 525 x 10 3 J
Q = 525,000 Joules
7. Ib dej hnyav 2 kg raug cua sov ntawm 24°C mus txog 90°C. Dej nqus cua sov npaum li cas. Qhov kub tshwj xeeb ntawm dej yog 4.2 × 10 3 J/Kg° C.
Paub:
Qhov hnyav (m) = 2 kg
Kub pib (T 1 ) = 24°C
Qhov kub kawg (T 2 ) = 90°C
Cov cua sov tshwj xeeb ntawm dej (c) = 4,200 Joules/kg°C
Xav tau :: Kub (Q)
Tshuaj:
Q = mc ΔT
Q = (2 kg)( 4,200 Joules/kg°C)(90°C – 24°C)
Q = (2 kg)( 4,200 Joules/kg°C)(66°C)
Q = (132)( 4,200 Joules)
Q = 554,400 Joules
[irp]
8. Ib tug dej 5-gram raug cua sov ntawm 10°C mus txog 40°C. Dej nqus tau cua sov npaum li cas. Qhov kub tshwj xeeb ntawm dej yog 1 × 10 3 cal / g r ° C.
Paub:
Qhov hnyav (m) = 5 grams
Kub pib (T1 ) = 10 o C
Qhov kub kawg (T2 ) = 40 o C
Qhov kub tshwj xeeb ntawm dej (c) = 1 c al / gr°C
Xav tau : Kub
Tshuaj:
Q = mc ΔT
Q = (5 grams) ( 1 cal/ gr°C) (40 o C – 10 o C)
Q = (5)( 1 c al)(30)
Q = 150 calories
9. Ib dej hnyav 0.2 -kg nqus tau 42,000 Joules ntawm qhov kub 25 o C. Qhov kub tshwj xeeb ntawm dej yog 4200 J/kg o C, qhov kub kawg ntawm dej yog dab tsi.
Paub:
Qhov hnyav ntawm dej (m) = 0.2 kg
Kub (Q) = 42,000 Joule
Cov cua sov tshwj xeeb ntawm dej (c) = 4200 J/kg o C
Kub pib (T1 ) = 25 o C
Xav tau: Qhov kub kawg (T 2 )
Tshuaj:
Q = mc ΔT = mc ( T2 – T1 )
Q = Thaum tshav kub kub, m = pawg, c = lub tshav kub tshwj xeeb, ΔT = qhov kev hloov pauv ntawm qhov kub thiab txias, T1 = qhov kub pib, T2 = qhov kub kawg
Q = mc ( T2 – T1 )
42,000 = (0.2)(4200)(T 2 – 25)
42,000 = 840 (T 2 – 25)
42,000 = 840 T 2 – 21,000
42,000 + 21,000 = 840 T 2
63,000 = 840 T 2
T 2 = 63,000 / 840
T2 = 75 oC
- Hloov cov nplai kub
- Kev nthuav dav ncaj
- Kev nthuav dav ntawm thaj chaw
- Kev nthuav dav ntawm ntim
- Thaum tshav kub kub
- Kev sib npaug ntawm cua sov
- Cov cua sov tshwj xeeb thiab lub peev xwm cua sov
- Kub latent, kub ntawm fusion, kub ntawm vaporization
- Kev txuag hluav taws xob rau kev hloov pauv cua sov
