5 Ngā tauira o ngā raruraru wera
1. Ko te wera motuhake o tētahi tine he 2 kirokaramu te taumaha, ko te 130 J.kg -1 C -1 . Ko te nui o te wera e mimitia ana e te tine hei whakapiki i tōna pāmahana mai i te 50 ° C ki te 100 ° C ko….
Kōrero
E mōhiotia ana:
Taumaha (m) = 2 kg
Te wera motuhake o te tine (c) = 130 J.kg -1 C -1
Huringa pāmahana (ΔT ) = 100 ° C – 50 ° C = 50 ° C
Pātai: Te wera (Q) e mimitia ana e te tine
Whakautu:
Tātai wera:
Q = mcΔT
Whakaahuatanga: Q = wera, m = papatipu, c = wera motuhake, ΔT = huringa pāmahana
Te wera e mimitia ana e te tine:
Q = (2 kg)(130 J.kg -1 C -1 )(50 o C)
Q = (100)(130)
Q = 13000 Joule
Q = 1,3 x 10 4 Joules
2. Ka pāngia te parahi me te wera motuhake o te 390 J kg -1 o C -1 e te huringa pāmahana o te 40 o C. Mena ko te wera i mimitihia e te parahi i te wā o te huringa pāmahana he 200 karori, ko te papatipu o te parahi ko...
Kōrero
E mōhiotia ana:
Te wera motuhake o te parahi (c) = 390 J kg -1 o C -1
Huringa pāmahana (ΔT ) = 40 ° C
Wera (Q) = 40 Joules
Pātai: Taumaha (m) o te parahi
Whakautu:
Q = mcΔT
40 = (m)( 390 )(40 ° C)
40 = (m)(390 )(40)
40 = (m)( 390 )(4)
40 = (m)( 1560 )
m = 40 / 1560
m = 0,026 kg
Ko te taumaha o te parahi he 26 karamu.
3. Ko te wai he 20 karamu te taumaha, ā, ko te wera motuhake o te 1 karori karamu -1 o C -1 i te tīmatanga he 30 o C te pāmahana. Tātaihia te huringa o te pāmahana o te wai mēnā he 300 karori te nui o te wera e mimitihia ana e te wai!
Kōrero
E mōhiotia ana:
Taumaha (m) = 20 karamu
Te pāmahana tīmatanga (T 1 ) = 30 ° C
Te wera motuhake o te wai (c) = 1 cal gr -1 o C -1
Wera (Q) = 300 karori
I pātaihia: Ngā huringa o te pāmahana wai
Whakautu:
Q = mcΔT
Q = mc (T 2 – T 1 )
300 karori = (20 karamu)( 1 karori karamu -1 o C -1 )(T 2 – 30 o C)
300 = (20)(1)(T 2 – 30)
300 = 20 (T 2 – 30)
300 = 20 T 2 – 600
300 + 600 = 20 T 2
900 = 20 T 2
T 2 = 900 / 20
T 2 = 45 ° C
Ngā huringa pāmahana:
ΔT = 45 ° C – 30 ° C
ΔT = 15 ° C
4. Te nui o te wera e hiahiatia ana hei whakaheke i te pāmahana o te 4 kg o te wai he 500 J/kg K te wera motuhake mai i te 40 oKa huri a C hei 20 oKo C…
A. 20 kJ
B. 30 kJ
C. 40 kJ
D. 50 kJ
E. 60 kJ
Kōrero:
E mōhiotia ana :
Taumaha (m) = 4 kg
Wera motuhake (c) = 500 J/kg K = 500 J/kg Co
Huringa pāmahana (delta T) = 40 oC - 20 oC = 20 Co
I pātaihia :
Wera (Q)
Whakautu :
Tātai Wera :
Q = (m)(c)(taura T)
Q = (4)(500)(20) = 40.000 Joule = 40 kJ
kJ = kiro Joule
Ko te whakautu tika ko C.
5. Ka whakamahanahia tētahi mea totoka, he 2 kg te taumaha, mai i te pāmahana 30oKa huri a C hei 100oC, e hiahiatia ana te wera 7 × 105 Joule. Ko te wera motuhake o te mea he…
A. 400 J/kg K
B. 500 J/kg K
C. 700 J/kg K
D. 1000 J/kg K
E. 5000 J/kg K
Kōrero:
E mōhiotia ana :
Taumaha (m) = 2 kg
Wera (Q) = 7 × 105 J = 700.000 J
Huringa pāmahana (delta T) = 100 oC - 30 oC = 70 Co
I pātaihia :
Te wera motuhake (c) ?
Whakautu :
c = Q / m T
c = 700.000 J / (2 kg)(70 C)o) = 700.000 J / 140 kg Co
c = 5000 J/kg Co
c = 5000 J/kg K
Ko te whakautu tika ko E.
