Laʻana o kahi ʻenekini wela (ka hoʻohana ʻana o ke kānāwai ʻelua o ka thermodynamics)

9 mau laʻana o nā pilikia mīkini wela (ka hoʻopili ʻana o ke kānāwai ʻelua o ka thermodynamics)

1. I hoʻokahi pōʻaiapuni, hoʻopili kahi ʻenekini i 3000 Joules o ka wela mai kahi waihona wela kiʻekiʻe a hōʻole i 1000 Joules o ka wela i kahi waihona wela haʻahaʻa. E hoʻoholo i ka pono o ka ʻenekini wela!

Pahana
ʻEnekini wela ʻAʻole like ka huaʻōlelo "carnot" i nā nīnau ma kēia ʻaoʻao me ka ʻenekini Carnot. He ʻenekini wela kūpono ka ʻenekini Carnot a aia wale nō ma ke kumumanaʻo. I ka hoʻohālikelike ʻana, ʻo ka ʻenekini wela i ʻōlelo ʻia ma kēia nīnau he ʻenekini wela maoli, ʻaʻole he ʻenekini wela kumumanaʻo (ka ʻenekini Carnot).
Ua ʻike ʻia :
Ka wela i omo ʻia (Q_H) = 3000 Joule
Hoʻokuʻu ʻia ka wela (Q_L) = 1000 Joule
Hana i hana ʻia e ka mīkini (W) = 3000 – 1000 = 2000 Joules
Ua nīnau ʻia Ka pono o ka mīkini wela (e)
Pane :

2. Hoʻopuka kahi ʻenekini wela i 2000 Joules o ka hana a hōʻole i 500 Joules o ka wela i hoʻokahi pōʻaiapuni. ʻO ka pono o ka ʻenekini…

Pahana
Ua ʻike ʻia :
Hana i hana ʻia e ka mīkini (W) = 2000 Joules
Hoʻokuʻu ʻia ka wela (Q_L) = 5000 Joule
Ka wela i omo ʻia (Q_H) = 2000 + 5000 = 7000 Joule
Ua nīnau ʻia Ka pono o ka mīkini wela (e)
Pane :

3. He 30% ka pono o kahi ʻenekini kaʻa. Inā hana ka ʻenekini i 10.000 Joules o ka hana i kēlā me kēia pōʻaiapuni, ehia ka nui o ka wela i hōʻole ʻia e ka ʻenekini i kēlā me kēia pōʻaiapuni?
Pahana
Ua ʻike ʻia :
Ka pono (e) = 30% = 30/100 = 0,3
Hana i hana ʻia e ka mīkini (W) = 3000 Joules
Ua nīnau ʻia : Ka wela i hoʻokuʻu ʻia e ka ʻenekini i kēlā me kēia pōʻaiapuni (Q_L)
Pane :
E helu i ka wela i omo ʻia (Q_H) me ka hoʻohana ʻana i ke ʻano hana pono (e) o kahi ʻenekini wela:
Ka wela i hoʻokuʻu ʻia i kēlā me kēia pōʻaiapuni (Q_L) = ka wela i omo ʻia (Q_H) – hana i hana ʻia (W)
Q_L = 10.000 Joules – 3000 Joules
Q_L = 7000 Joule

Ka pono o nā ʻenekini wela, nā ʻenekini Carnot

4. Hoʻopili kahi ʻenekini wela i 3.000 Joules o ka wela mai kahi waihona wela kiʻekiʻe a hōʻole i 2.400 Joules i kahi waihona wela haʻahaʻa. ʻO ka pono o ka ʻenekini he ….
A. 10%
B. 15%
C. 20%
D. 30%
E. 40%
Kūkākūkā:
Ua ʻike ʻia :
Q_H = 3000 Joules, Q_L = 2400 Joule.
Ua nīnau ʻia :
Ka pono (e) o kahi ʻenekini wela?
Pane :
ʻO C ka pane pololei.

5. He waihona wela kiʻekiʻe ko kahi ʻenekini Carnot he 300 ^oC a me ka waihona wai mahana haʻahaʻa 80 ^oC. ʻO ka pono o ka mīkini…
A. 38%
B. 45%
C. 50%
D. 58%
E. 67%
Kūkākūkā:
Ua ʻike ʻia :
T_L = 80^oC = (80 + 273) K = 353 K
T_H = 300^oC = (300 + 273) K = 573 K
Inā ʻike ʻia ka mahana ma nā anakahi Celsius, pono e hoʻololi ʻia i nā anakahi Kelvin (ʻo Kelvin ka International System of units for temperature).
Ua nīnau ʻia :
Ka pono (e) o kahi ʻenekini Carnot?
Pane :

ʻO A ka pane pololei.

6. ʻO ke kiʻekiʻe o ka mahana o ka waihona ʻenekini Carnot he 600 K a ʻo kona pono he 60%. No ka hoʻokō ʻana i ka pono he 70%, pono ke kiʻekiʻe o ka mahana o ka waihona ʻenekini Carnot...
A. 500 K
B. 800 K
C. 1000 K
D. 1200 K
E. 1500 K
Kūkākūkā:
Ua ʻike ʻia :
ʻIkepili 1: T_H = 600 K, e = 60%
ʻIkepili 2: T_H = …. K ?, e = 70 %
Ua nīnau ʻia :
Mahana kiʻekiʻe (T_H)
Pane :
E hoʻohana i ka ʻikepili 1 e helu i ka mahana haʻahaʻa (T_L).
E hoʻohana iā T_L a me ka ʻikepili 2 e helu i ka mahana kiʻekiʻe (T_H):
No ka hoʻokō ʻana i ka pono o 70%, ʻo ke ana wela kiʻekiʻe = 800 Kelvin.
ʻO ka pane pololei ʻo B.

7. E nānā i ka pakuhi PV o ka ʻenekini Carnot ma lalo. Inā ʻo W = 5000 Joules, a laila ʻo ka nui o ka wela i hoʻokuʻu ʻia e ka ʻenekini i kēlā me kēia pōʻaiapuni he...
A. 2.315 Joule
B. 3.475 Joule
C. 3.750 Joule
D. 5.000 Joule
E. 5.600 Joule

Kūkākūkā:
Ua ʻike ʻia :
W = 5000 Joule
T_H = 780 K
T_L = 320 K
Ua nīnau ʻia :
Q₂ ?
Pane :
Ka pono o ka mīkini Carnot:
e = 1 – (T_L/T_H) = 1 – (320/780) = 1 – 0,41 = 0,59
Hoʻohana wale ʻia he 59% o ka wela e hana i ka hana. E hoʻohana i kēia ʻikepili e helu i ka wela i omo ʻia e ka mīkini Carnot (Q₁).
(0,59)(Q₁) = 5000 Joule
Q₁ = 5000 Joules/0,59 = 8475 Joules
ʻO ka nui o ka wela i omo ʻia e ka ʻenekini he 8475 Joules.
ʻO ka nui o ka wela i hoʻokuʻu ʻia e ka ʻenekini i kēlā me kēia pōʻaiapuni:
W = Q₁ – Q₂
5000 Joules = 8475 Joules – Q₂
Q₂ = 8475 Joules – 5000 Joules
Q₂ = 3475 Joule
ʻO ka pane pololei ʻo B.

8. E nānā i ke kiʻikuhi PV o ka mīkini Carnot ma lalo! Inā ua omo ka wela (Q₁) = 8000 Joules a laila ʻo ka hana i hana ʻia e ka ʻenekini Carnot…
A. 1640 J
B. 4720 J
C. 5640 J
D. 6270 J
E. 8840 J

Kūkākūkā:
Ua ʻike ʻia :
Q₁ = 8000 J
T_H = 820 K
T_L = 380 K
Ua nīnau ʻia :
ʻO W?
Pane :
Ka pono o ka mīkini Carnot:
e = 1 – (T_L/T_H) = 1 – (380/820) = 1 – 0,46 = 0,54
Hoʻohana wale ʻia he 54% o ka wela e hana i ka hana. E hoʻohana i kēia ʻikepili e helu i ka hana i hana ʻia e ka ʻenekini Carnot (W).
(0,59)(8000) = 4720 Joules
ʻO ka hana i hana ʻia e ka ʻenekini Carnot he 4720 Joules.
ʻO ka pane pololei ʻo B.

9. Hana kahi ʻenekini Carnot ma waena o kahi waihona wela o 520 ^oC a me ka waihona anu 110 ^oC. Inā omo ka mīkini i 3000 Joules o ka wela mai ka waihona wela, a laila ʻo ka nui o ka wela i hōʻole ʻia mai ka mīkini he...
A. 450 joules
B. 800 joules
C. 1000 mau minuke
D. 1200 joules
E. 1440 joules
Kūkākūkā:
Ua ʻike ʻia :
T_H = 520 + 273 = 793 K
T_L = 110 + 273 = 383 K
Q₁ = 3000 J
Ua nīnau ʻia :
Q₂ = … ?
Pane :
Ka pono o ka mīkini Carnot:
e = 1 – (383/793) = 1 – 0,48 = 0,52
E hoʻohana i kēia ʻikepili e helu i ka hana i hana ʻia e ka ʻenekini (W)
(0,52)(3000) = 1560 Joules
ʻO ka mana o ka hana i hana ʻia e ka mīkini he 1560 Joules.
Ka nui o ka wela i hoʻokuʻu ʻia e ka ʻenekini:
Q₂ = 3000 Joules – 1560 Joules
Q₂ = 1440 Joule
ʻO ka wela i hoʻokuʻu ʻia e ka ʻenekini he 1440 Joules.