Tambayoyin Misali na Bakar Ka'ida

Misalai 15 na Tambayoyin Ka'idojin Baƙar fata

1. Kankara mai nauyin kilogiram 0,2 ana gauraya ta da shayi mai dumi mai nauyin kilogiram 0,2. Zafin kankara = - 10 ^oC , zafin shayi mai dumi = 40 ^oC . Zafin kankara na musamman = 2100 J/kg C ^o , zafin ruwa na musamman = 4200 J/kg C ^o , zafin haɗuwar ruwa = 334.000 J/kg. Idan kankara da shayi mai dumi an gauraya su a cikin tsarin rufewa, a tantance zafin ƙarshe na cakuda.

Tattaunawa
An sani :
Nauyin kankara (m es) = 0,2 kg
Nauyin ruwan shayi mai dumi (m shayi) = 0,2 kg
Takamaiman zafin ruwa (c ruwa) = 4180 J/kg C^o
Takamaiman zafin kankara (c es) = 2100 J/kg C^o
Zafin haɗakar ruwa (L)_f ruwa) = 334.000 J/kg
Zafin kankara (T es) = -10^oC
Ruwan shayi mai dumi (T shayi) = 40^oC
An tambaya : zafin ƙarshe na cakuda (haɗin T)?
Jawab :
Mataki na farko, kimanta yanayin ƙarshe.
Zafin da dole ne a saki ta ruwa don rage zafin 0,2 kg na shayi mai dumi daga 40^oC zuwa 0^oC:
Zafin da kilogiram 0,2 na kankara ke sha don ɗaga zafinsa daga -10^oC zuwa 0^oC:
Zafin da ake sha don narke 0,2 kg na kankara (zafin da ake buƙata don canza dukkan kankara zuwa ruwa):
Dangane da lissafin da ke sama, an sami sakamako masu zuwa:
An saki Q = 33,444 kJ
An karɓi Q = 4,2 kJ
Q narkewa = 66,8 kJ

Idan shayin zafi ya fitar da zafi 33,44 kJ, zafin shayin mai zafi yana canzawa daga 40oC zuwa 0oC. Ana amfani da wasu daga cikin zafin da aka saki (kimanin 4,2 kJ) don ɗaga zafin kankara daga -10oC ^zuwa 0oC ^. 33,44 kJ – 4,2 kJ = 29,24 kJ. Don narke dukkan kankara zuwa ruwa, ana buƙatar 66,8 kJ na zafi. Sauran zafin shine 29,24 kJ.

Za a iya kammala da cewa zafin da shayin zafi ke fitarwa ana amfani da shi ne kawai don ɗaga zafin kankara daga -10 ^° C zuwa 0 ^° C da kuma narke wasu kankara. Wasu kankara sun koma ruwa, yayin da wasu ba su canza ba. A lokacin sauyawa daga daskararre zuwa ruwa, zafin bai canza ba. Saboda haka, zafin ƙarshe na cakuda shine 0 ^° C.

2. Nauyin shayi mai zafi = 0,4 kg, nauyin kankara = 0,2 kg, zafin cubes na kankara = -10^oC, zafin shayi mai zafi = 90^oC. Idan duka biyun sun haɗu, menene zafin ƙarshe na cakuda?
Tattaunawa
Mataki na farko: kimanta yanayin ƙarshe
Zafin da dole ne a saki ta ruwa don rage zafin 0,4 kg na ruwan shayi mai zafi daga 90^oC zuwa 0^oC:
Zafin da kilogiram 0,2 na kankara ya samu ya ɗaga zafinsa daga -10^oC zuwa 0^oC:
Zafin da ake buƙata don narke 0,2 kg na kankara (zafin da ake buƙata don canza dukkan kankara zuwa ruwa):
Dangane da lissafin da ke sama, an sami sakamako masu zuwa:
An saki Q = 150,48 kJ
An karɓi Q = 4,2 kJ
Q narkewa = 66,8 kJ
Idan shayin zafi ya fitar da zafi 150,48 kJ, zafin shayin mai zafi yana canzawa daga 90oC zuwa 0oC. Ana amfani da wasu daga cikin zafin da aka saki (4,2 J) don ɗaga zafin kankara daga -10 oC zuwa 0oC. 150,48 kJ – 4,8 kJ = 146,28 kJ. Sauran zafi = 146,28 kJ.
Zafin da ake buƙata don narke dukkan ƙanƙara zuwa ruwa shine 66,8 kJ kawai. 146,28 kJ – 66,8 kJ = 79,48 kJ. Shayin zafi ba ya buƙatar sakin dukkan zafinsa har sai zafinsa ya ragu zuwa 0.^oC. A ƙarshe, zafin ƙarshe na cakuda dole ne ya fi 0^oC.

Mataki na biyu: ƙayyade zafin jiki na ƙarshe (T)
Zafin da ake buƙata don ɗaga zafin kankara daga -10^oC zuwa 0^oC shine 4200 J.
Zafin da ake buƙata don narke dukkan kankara zuwa ruwa (zafin da ke ɓoye) = 66.800 J
Zafin da ake buƙata don ɗaga zafin ruwan (ruwan da ke fitowa daga narkar da dukkan kankara) daga 0^oC zuwa T^oC = (tarin kankara)(zafin ruwa na musamman)(T – 0) = (0,2)(4180)(T) = 836 T
Zafin da shayin ɗumi ke fitarwa don rage zafinsa daga 90oC zuwa T = (yawan ruwa)(90-T) = (0,4)(4180)(90 – T) = 1672 (90-T) = 150.480 – 1672 T

 

3. Ana haɗa gram 60 na ruwa a zafin jiki na 90 ^oC (takamaiman zafin ruwa = 1 cal.g ^-1 . ^o C ^{-1 ) da gram 40 na ruwa iri ɗaya a zafin jiki na 25 oC} . Idan babu wasu abubuwan da ke shafar wannan tsari, to zafin ƙarshe na cakuda shine...

A. 15,4 ^oC
B. 23,0 ^oC
C. 46,0 ^oC
D. 64,0 ^oC
E. 77,0 ^oC

Tattaunawa
An sani :
Nauyin ruwa 1 (m₁= gram 60)
Zafin ruwa 1 (T)₁) = 90^oC
Nauyin ruwa 2 (m₂= gram 40)
Zafin ruwa 2 (T)₂) = 25^oC
Takamaiman zafi ruwa (c) = 1 kalori^-1.^oC^-1
An tambaya : zafin jiki cakuda na ƙarshe
Jawab :
Zafin da ruwan zafin jiki mai yawa ke fitarwa (Q ya saki) = zafi da ruwan zafin jiki mai ƙarancin zafi ke sha (Q ya sha)
m₁ c (ΔT) = m₂ c (ΔT)
(60)(1)(90 – T) = (40)(1)(T – 25)
(60)(90 – T) = (40)(T – 25)
5400 – 60T = 40T – 1000
5400 + 1000 = 40T + 60T
6400 = 100T
T = 6400/100
T = 64^oC
Amsar da ta dace ita ce D.

4. Wani yanki na aluminum yana da nauyin gram 500 kuma yana da zafin jiki na 30 ^oAna saka C a cikin kwano mai ɗauke da ruwa mai nauyin gram 200 kuma zafinsa ya kai digiri 90 ^oC. Idan an san takamaiman zafin aluminum shine 0,22 cal/g C^o kuma takamaiman zafin ruwa shine 1 cal/g C^o, to zafin ƙarshe na ruwa da aluminum shine...
A. 20,3 ^oC
B. 42,2 ^oC
C. 68,7 ^oC
D. 80,5 ^oC
E. 100 ^oC
Tattaunawa:
Ba sai an canza naúrar nauyi, gram (g) zuwa kilogiram (kg) ba saboda takamaiman zafin aluminum da takamaiman zafin ruwa ana bayyana su a cikin cal/g C^o.
An sani :
aluminum m = gram 500
c aluminum = 0,22 kalori/gC^o
Aluminum T = 30 ^oC
ruwa m = gram 200
ruwa c = 1 kalori/gC^o
T ruwa = 90 ^oC
An tambaya :
Zafin ƙarshe (T) na ruwa da aluminum?
Jawab :

Tsarin zafi : Q = (m)(c)(delta T)

Q ruwa = = (gram 200)(cal 1/gC)^o)(90 ^oC-T)
Q aluminum = (gram 500)(0,22 cal/gC)^o)(T– 30 ^oC)

Tsarin Baƙar fata : _{An saki} Q = _{an sha Q}

Ruwa yana da zafin farko mafi girma (90 ^oC) don ruwa ya saki zafi, aluminum yana da ƙarancin zafin farko (30) ^oC) don aluminum ya sha zafi. Zafin ƙarshe na cakuda ruwa da aluminum dole ne ya zama ƙasa da zafin farko na ruwan kuma ya fi zafin farko na aluminum.
(gram 200)(cal 1/gC)^o)(90 ^oC – T) = (gram 500)(0,22 kalori/g C^o)(T– 30 ^oC)
(200)(1)(90-T) = (500)(0,22)(T-30)
(200)(90-T) = (110)(T-30)
18000 – 200 T = 110 T – 3300
18000 + 3300 = 110 T + 200 T
21300 = 310 T
T = 68,7 ^oC
Zafin ƙarshe na haɗakar ruwa da aluminum shine 68,7 ^oC.
Amsar da ta dace ita ce C.

5. Wani ƙarfe mai nauyin gram 300 a zafin jiki na 80 ^oAn tsoma C a cikin gram 200 na ruwa a digiri 40 ^oC. Takamaiman zafin ruwa = 1 cal/g C^oIdan zafin ƙarshe na cakuda ƙarfe da ruwa ya kai 50^o C kuma akwati ba ya shan zafi, to takamaiman zafin ƙarfe shine…
A. 0,15 kalori/g C^o
B. 0,22 kalori/g C^o
C. 1,50 kalori/g C^o
D. 4,8 kalori/g C^o
E. 7,2 kalori/g C^o
Tattaunawa:
An sani :
ƙarfe m = gram 300
T ƙarfe = 80 ^oC
ruwa m = gram 200
T ruwa = 40 ^oC
c ruwa = 1 kalori/g C^o
Cakuda ta ƙarshe ta ƙarfe da ruwa = 50 ^oC
An tambaya :
c ƙarfe?
Jawab :
Q ƙarfe = (m)(c)(delta T) = (gram 300)(c ƙarfe)(80)^oC - 50^oC) = (gram 300)(c ƙarfe)(30 C)^o)
Q ruwa = (m)(c)(delta T) = (gram 200)(cal 1/g C)^o)(60^oC - 50^oC) = (gram 200)(cal 1/g C)^o)(10 C^o)

Tsarin Baƙar fata : _{An saki} Q = _{an sha Q}

Karfe yana da zafin farko mafi girma (80 ^oC) don ƙarfe ya saki zafi, ruwan yana da ƙarancin zafin farko (40) ^oC) domin ruwan ya sha zafi.
(gram 300)(c ƙarfe)(30 C)^o) = (gram 200)(cal 1/g C^o)(10 C^o)
(300)(c)(30) = (200)(1)(10)
9000 c = 2000
c = 2000 / 9000
c = 0,22 kalori/g C^o
Takamaiman zafin ƙarfe shine 0,22 cal/g C^o.
Amsar da ta dace ita ce B.

6. Kwallaye biyu iri ɗaya suna da yanayin zafi iri ɗaya na 40 ^oC, ƙwallan biyu suna da nauyin gram 10 da gram 40 bi da bi. Ana sanya ƙwallan biyu a cikin ruwa, don haka zafin ƙwallan biyu ya tashi zuwa 60^oC. Idan takamaiman zafin ƙwallon shine 2 cal/gr C^o da kuma kalori 1 = Joules 4,2, to bambancin zafi da kowace ƙwallon ke sha shine...
A. 5,04 x 10³ Joule
B. 7,50 x 10³ Joule
C. 10,6 x 10³ Joule
D. 40 x 10³ Joule
E. 42 x 10³ Joule
Tattaunawa:
An sani :
m₁ = gram 10
m₂ = gram 40
T₁ = T ba₂ = 40 ^oC
T _karshen = 60 ^oC
ƙwallon c = 2 kalori/gr C^o
An tambaya :
Menene bambanci a cikin zafin da kowace ƙwallon ke sha?
Jawab :
Zafin ƙwallo biyu yana ƙaruwa saboda dole ne ƙwallo biyu su sha zafi.
Q₁ = (10 gr)(2 kal/gr C^o)(60^oC–40^oC) = (10 gr)(2 kalori/gr C)^o)(20 C^o= 400 cal = (400) (4,2 J) = 1680 Joules
Q₂ = (40 gr)(2 kal/gr C^o)(60^oC–40^oC) = (40 gr)(2 kalori/gr C)^o)(20 C^o= 1600 cal = (1600) (4,2 J) = 6720 Joules
Bambancin zafi da kowace ƙwallo ke sha:
6720 J - 1680 J = 5040 J = 5,04 x 10³ J
Amsar da ta dace ita ce A.

7. Ruwan da nauyinsa ya kai gram 200 a zafin jiki na 30°C an gauraya shi da ruwan zãfi mai nauyin gram 100 da zafin jiki na 90°C. (Takamaiman zafin ruwa = 1 cal.gram ^-1 °C ^-1 ). Zafin ruwan da aka gauraya a lokacin da aka daidaita zafin shine….

A. 10°C

B. 30°C

C. 50°C

D. 75°C

E. 150°C

Tattaunawa

An sani cewa :

Nauyin ruwa 1 (m1 ₎ = gram 200

Zafin ruwa 1 (T1 ₎ = 30 ^oC

Nauyin ruwa 2 (m2 ₎ = gram 100

Zafin ruwa 2 (T2 ₎ = 90 ^oC

Takamaiman zafin ruwa (c) = 1 cal.gram ⁻¹ °C ⁻¹

An tambaya : zafin ƙarshe na cakuda

Amsa :

Zafin da ruwan zafin jiki mai yawa ke fitarwa (Q ya saki) = zafi da ruwan zafin jiki mai ƙarancin zafi ke sha (Q ya sha)

Amsar da ta dace ita ce C.

8. gram 60 na ruwa a zafin jiki na 90 ^oC (takamaiman zafin ruwa = 1 cal.g ^-1 . ^o C ^-1 ) an haɗa shi da gram 40 na ruwa iri ɗaya a zafin jiki na 25 ^oC . Idan babu wasu abubuwan da ke shafar wannan tsari, to zafin ƙarshe na cakuda shine...

A. 15,4 ^o C

B. 23,0 ^o C

C. 46,0 ^o C

D. 64,0 ^o C

E. 77,0 ^o C

Tattaunawa

An sani cewa :

Nauyin ruwa 1 (m1 ₎ = gram 60

Zafin ruwa 1 (T1 ₎ = 90 ^oC

Nauyin ruwa 2 (m2 ₎ = gram 40

Zafin ruwa 2 (T2 ₎ = 25 ^oC

Takamaiman zafin ruwa (c) = 1 cal.g ^-1 . ^o C ^-1

An tambaya : zafin ƙarshe na cakuda

Amsa :

Zafin da ruwan zafin jiki mai yawa ke fitarwa (Q ya saki) = zafi da ruwan zafin jiki mai ƙarancin zafi ke sha (Q ya sha)

Amsar da ta dace ita ce D.

9. Kankara mai nauyin gram M a zafin jiki na 0 ^oC , ana saka ta a cikin ruwa mai nauyin gram 340 a zafin jiki na 20 ^{oC wanda aka sanya a cikin wani akwati na} musamman. A ɗauka cewa jirgin bai sha/saki zafi ba. Idan _kankara mai ƙarfi = 80 cal g ^-1 , c _ruwa = 1 cal g ^{-1 oC} -1 , duk kankara yana narkewa kuma ana isa ga daidaiton zafi a zafin jiki na 5 ^oC , to nauyin kankara (M) zai...

A. gram 60

B. gram 68

C. 75 grams

D. gram 80

E. gram 170

Tattaunawa

An sani cewa :

Nauyin ruwa (m) = gram 340

Zafin kankara (T es ₎ = 0 ^oC

Zafin ruwa (T ruwa ₎ = 20 ^oC

Zafin jiki na daidaiton zafi (T) = 5 ^oC

Zafin kankara mai narkewa (L ₎ = 80 kcal g ^-1

Takamaiman zafin ruwa (c _ruwa ) = 1 kalori g ^{-1 o} C ^-1

Tambaya : Yawan kankara (M)

Amsa :

Ka'idar Black ta bayyana cewa a cikin tsarin rufewa da aka keɓe, zafin da wani abu mai zafi mai yawa ke fitarwa daidai yake da zafin da wani abu mai ƙarancin zafin jiki ke sha.

Zafin da ruwa ke fitarwa (Q ya saki) = zafi da kankara ke sha (Q ya sha)

Amsar da ta dace ita ce A.

Catatan :

Idan aka ce kankara tana da zafin 0 ^o to ruwan yana nan a cikin siffa mai ƙarfi. Idan aka ce ruwa yana da zafin 0 ^o C to ruwan yana cikin siffa mai ruwa. Bambanta amfani da kalmomin kankara da ruwa. Domin ruwan har yanzu yana cikin siffa mai ƙarfi ko kankara, ana fara amfani da zafin da aka sha don narke dukkan kankara zuwa ruwa, saboda haka a gefen dama na lissafin da ke sama an ƙara dabara don ƙididdige adadin zafi don narke kankara (me _es L _es ). Bayan duk kankara ta narke zuwa ruwa, ana amfani da ƙarin zafi don ɗaga zafin kankara daga 0 ^o C zuwa 5 ^o C.

10. Ana saka ƙarfen tagulla a zafin jiki na 100 ^oC a cikin ruwa mai nauyin gram 128 da zafin jiki na 30 ^{oC .} Takamammen zafin ruwa shine 1 cal.g ^-1oC -1 kuma takamaiman zafin jan ƙarfe shine 0,1 cal.g ^{-1oC -1} . Idan daidaiton zafi ya faru a zafin jiki na 36 ^oC , to nauyin ƙarfe shine….

A. gram 140

B. gram 120

C. 100 grams

D. gram 80

E. gram 75

Tattaunawa

An san cewa:

Zafin jan ƙarfe (T ₁ ) = 100 ^oC

Takamaiman zafin jan ƙarfe (c1 ⁾ ₌ 0,1 cal.g ^-1oC -1

Nauyin ruwa (m2 ₎ = gram 128

Zafin ruwa (T2 ) ₌ 30 ^oC

Takamaiman zafin ruwa (c2 ⁾ ₌ 1 cal.g ^-1oC -1

Zafin jiki na daidaiton zafi ( T) = 36 ^oC

Tambaya: Nauyin jan ƙarfe (m ₁ )

Amsa:

Ka'idar Black ta bayyana cewa zafin da wani abu mai zafi mai yawa ke fitarwa = zafin da wani abu mai ƙarancin zafi ke karɓa.

Amsar da ta dace ita ce B.

11. Ana tsoma kilogiram uku na sandar gubar baki tare da takamaiman zafi na 1400 J.kg ^-1 C ^-1 a zafin jiki na 80 ^{oC a cikin kilogiram 10 na ruwa tare da takamaiman zafi na 4200 J.kg -1} C ^-1 . Bayan daidaiton zafi ya faru, zafin ƙarshe na cakuda shine 20 ^oC . Zafin farko na ruwan shine….

A. 20 ^o C

B. 18 ^o C

C. 14 ^o C

D. 12 ^o C

E. 10 ^o C

Tattaunawa

An san cewa:

Nauyin gubar (m ₁ ) = 3 kg

Takamaiman zafin tin (c1 ₎ = 1400 J.kg ^-1 C ^-1

Zafin Tin (T ₁ ) = 80 ^oC

Nauyin ruwa (m2 ₎ = 10 kg

Takamaiman zafin ruwa (c2 ₎ = 4200 J.kg ^-1 C ^-1

Zafin jiki na daidaiton zafi ( T) = 20 ^oC

Ana so: Zafin ruwan farko ( _T2 )

Amsa:

Amsar da ta dace ita ce C.

12. Ana dumama tsabar kudin gram 50 zuwa zafin jiki na 85 ^oC , sannan a tsoma a cikin kwano mai dauke da gram 50 na ruwa a zafin jiki na 29,8 ^oC (takamaiman zafin ruwa = 1 cal.g ^-1 . ^o C ^-1 ). Idan zafin jiki na ƙarshe na tsarin shine 37 ^oC kuma ana ɗauka babu canji a cikin zafi ta cikin kwano, to takamaiman zafin ƙarfe shine...

A. 0,12 cal.g ^-1 . ^o C ^-1

B. 0,30 kalori g ^-1 . ^o C ^-1

C. 1,50 kalori g ^-1 . ^o C ^-1

D. 4,8 kalori g ^-1 . ^o C ^-1

E. 7,2 cal.g ^-1 . ^o C ^-1

Tattaunawa

An san cewa:

Nauyin tsabar kuɗi (m) = gram 50

Zafin farko na tsabar kudin (T 1 ₎ = 85 ^oC

Nauyin ruwa (m) = gram 50

Zafin ruwa na farko ( T ₂ ) = 29,8 ^oC

Takamaiman zafin ruwa = 1 cal.g ^-1 . ^o C ^-1

Zafin tsarin ƙarshe (T) = 37 ^oC

Tambaya: Takamaiman zafin ƙarfe (c)

Amsa:

Ka'idar Black ta bayyana cewa zafi da aka saki = zafi da aka sha. Ana sakin zafi ta hanyar tsabar kuɗi kuma zafi yana sha ta hanyar ruwa, har sai an kai ga daidaiton zafi.

Ana bayyana dukkan raka'a a cikin gram don haka babu buƙatar canza raka'a.

_{An cire} Q = _{An sha Q}

_ƙarfe m c ΔT = m _ruwa c ΔT

(50)(c)(85-37) = (50)(1)(37-29,8)

(50)(c)(48) = (50)(7,2)

(50)(c)(48) = (50)(7,2)

(c)(48) = 7,2

c = 7,2 / 48

c = 0,15 kalori g ^-1 . ^o C ^-1

13. Ana saka ƙarfen tagulla a zafin jiki na 100 ^oC a cikin ruwa mai nauyin gram 128 da zafin jiki na 30 ^oC . Takamammen zafin ruwa shine 1 cal.g ^{-1 oC} -1 ^kuma takamaiman zafin jan ƙarfe shine 0,1 cal.g ^{-1 oC -1} . Idan daidaiton zafi ya faru a zafin jiki na 36 ^oC , to nauyin ƙarfe shine….

A. gram 140
B. gram 120
C. 100 grams
D. gram 80
E. gram 75

Tattaunawa
An san cewa:
Zafin jan ƙarfe (T)₁) = 100 ^oC
Takamaiman zafin jan ƙarfe (c)₁) = 0,1 kalori^{-1 o}C^-1

Yawan ruwa (m₂= gram 128)
Zafin ruwa (T)₂) = 30 ^oC
Takamaiman zafin ruwa (c₂) = 1 kalori^{-1 o}C^-1

Zafin jiki na daidaiton zafi (T) = 36 ^oC
Tambaya: Nauyin jan ƙarfe (m₁)
Amsa:

Ka'idar Black ta bayyana cewa zafin da wani abu mai zafi mai yawa ke fitarwa = zafin da wani abu mai ƙarancin zafi ke karɓa.
Q jan ƙarfe = Q ruwa
m₁ c₁ ΔT = m₂ c₂ ΔT
(m₁)(0,1)(100-36) = (128)(1)(36-30)
(m₁)(0,1)(64) = (128)(1)(6)
(m₁)(6,4) = 768
m₁ = 768/6,4
m₁ = 120
Nauyin jan ƙarfe shine gram 120.
Amsar da ta dace ita ce B.

14. Ana tsoma kilogiram uku na sandar gubar baki tare da takamaiman zafi na 1400 J.kg ^-1 C ^-1 a zafin jiki na 80 ^{oC a cikin kilogiram 10 na ruwa tare da takamaiman zafi na 4200 J.kg -1} C ^-1 . Bayan daidaiton zafi ya faru, zafin ƙarshe na cakuda shine 20 ^oC . Zafin farko na ruwan shine….

A. 20 ^oC
B. 18 ^oC
C. 14 ^oC
D. 12 ^oC
E. 10 ^oC

Tattaunawa
An san cewa:
Nauyin gubar (m₁) = 3 kg
Takamaiman zafin tin (c)₁) = 1400 J.kg^-1 C^-1
Zafin Tin (T)₁) = 80 ^oC

Yawan ruwa (m₂) = 10 kg
Takamaiman zafin ruwa (c₂) = 4200 J.kg^-1 C^-1

Zafin jiki na daidaiton zafi (T) = 20 ^oC
Ana buƙata: Zafin ruwan farko (T)₂)
Amsa:
An saki Q = An karɓi Q
Q tin = Q ruwa
m₁ c₁ ΔT = m₂ c₂ ΔT
(3)(1.400)(80-20) = (10)(4.200)(20-T)
(4.200)(60) = (42.000)(20-T)
252.000 = 840.000 – 42.000 T
42.000 T = 840.000 – 252.000
42.000 T = 588.000
T = 588.000 / 42.000
T = 14
Zafin ruwan farko shine 14^oC.
Amsar da ta dace ita ce C.

15. Kankara mai nauyin gram M a zafin jiki na 0 ^oC , ana saka ta a cikin ruwa mai nauyin gram 340 a zafin jiki na 20 ^{oC wanda aka sanya a cikin wani akwati na} musamman. A ɗauka cewa jirgin bai sha/saki zafi ba. Idan _kankara mai ƙarfi = 80 cal g ^-1 , c _ruwa = 1 cal g ^{-1 oC} -1 , duk kankara yana narkewa kuma an cimma daidaiton zafi a zafin jiki na 5 ^oC , to nauyin kankara (M) zai...

A. gram 60
B. gram 68
C. 75 grams
D. gram 80
E. gram 170

Tattaunawa
An sani :
Nauyin ruwa (m) = gram 340
Zafin kankara (T)_es) = 0^oC
Suhu ruwa (T)_iska) = 20^oC
Zafin jiki na daidaiton zafi (T) = 5^oC
Zafin haɗewar kankara (L)_es) = 80 kalori g^-1
Takamaiman zafin ruwa (c_iska) = 1 kalori g^{-1 o}C^-1
An tambaya : Yawan kankara (M)
Jawab :

Ƙa'idar Baƙi ya bayyana cewa a cikin tsarin rufewa da aka keɓe, zafin da wani abu mai zafi mai yawa ke fitarwa iri ɗaya ne da zafin da wani abu mai ƙarancin zafin jiki ke sha.
Zafin da ruwa ke fitarwa (Q ya saki) = zafi da kankara ke sha (Q ya sha)
m_iska c_iska (T) = m_es L_es +m_es c_iska (T)
(340)(1)(20-5) = M (80) + M (1)(5-0)
(340)(15) = 80M + 5M
5100 = 85M
M = 5100/85
M = gram 60
Amsar da ta dace ita ce A.

Catatan :
Idan aka ce kankara tana da zafin jiki na 0^o to ruwan har yanzu yana cikin tsari mai ƙarfi. Idan aka ce zafin ruwan shine 0^oC sannan ruwan yana cikin siffa ta ruwa. Bambanta amfani da kalmomin kankara da ruwa. Domin har yanzu ruwan yana cikin siffa ta tauri ko ta kankara, ana amfani da zafin da aka sha da farko don narke dukkan kankara zuwa ruwa, saboda haka a gefen dama na lissafin da ke sama, an ƙara dabara don ƙididdige adadin zafi don narke kankara (m)_es L_esBayan duk ƙanƙarar ta narke ta zama ruwa, ana amfani da ƙarin zafi don ɗaga zafin ƙanƙarar daga 0^oC ya zama 5^oC.

Tushen tambaya:

Tambayoyin Nazarin Fizik na Ƙasa ga Makarantar Sakandare ta Babbar Sakandare/Makarantar Sakandare ta Sana'a