Kumumanaʻo ʻEleʻele

Ke Hoʻomaopopo nei i nā Kumumanaʻo ʻEleʻele

Inā hoʻohui mākou i ka wai wela a me ke anuanu i loko o kahi pahu hāmama (no ka laʻana, he bākeke), hoʻoili ka wela mai ka wai wela i ka wai anuanu. No ka mea ua hāmama ka pahu, hoʻoili kekahi o ka wela i ka lewa. Lilo pū ka pahu i mea mehana. ʻAʻole wale ka wela i hoʻokuʻu ʻia e ka wai wela e omo ʻia e ka wai anuanu akā e ka lewa a me ka pahu pū kekahi. I kēia hihia, he ʻōnaehana ka bākeke ʻaʻole i hoʻokaʻawale ʻia.

Ke hoʻohuihui mākou i ka wai wela a me ke anuanu i loko o kahi thermos pani ʻia, hoʻoili ka wela mai ka wai wela a i ka wai anuanu. He ʻōnaehana kaʻawale ka thermos , no laila ʻaʻohe hoʻoili wela i ka lewa a i ʻole ka thermos. ʻO ka wela i hoʻokuʻu ʻia e ka wai wela e omo wale ʻia e ka wai anuanu a hiki i ka hui ʻana i ke kaulike wela.

ʻŌlelo ke kumumanaʻo o Black i loko o kahi ʻōnaehana pani kaʻawale, ʻo ka wela i hoʻokuʻu ʻia e kahi mea wela kiʻekiʻe = ka wela i omo ʻia e kahi mea wela haʻahaʻa.

ʻO ke ʻano hana maʻamau o Black
Q_pio =Q_omo
Wehewehe: Q_pio = ka wela i hoʻokuʻu ʻia e kahi mea wela kiʻekiʻe, Q_omo = ka wela i omo ʻia e nā mea mahana haʻahaʻa.

Nā nīnau hoʻohālike no ke kumumanaʻo o Black

1. He ʻāpana hao wela me ke kaumaha o 1 kg a me ka mahana o 100 ^oHoʻokomo ʻia ʻo C i loko o kahi pahu i loaʻa ka wai me ke kaumaha o 2 kg a me ka mahana o 20 ^oC. He aha ka mahana hope loa o ka hui ʻana? Ka wela kikoʻī o ka hao = 450 J/kg C^o, ka wela kikoʻī o ka wai = 4200 J/kg C^o.
Kūkākūkā:
Ua ʻike ʻia :
hao m = 1 kg, T_{pā aku} = 100 ^oC, m wai = 2 kg, T_ea = 20 ^oC, c hao = 450 J/kg C^o, c wai = 4200 J/kg C^o.
Ua nīnau ʻia :
T hui?
Pane :
ʻOi aku ka mahana o ka hao ma mua o ka wai no laila hoʻokuʻu ka hao i ka wela, omo ka wai i ka wela.
(m)(c)(delta T) = (m)(c)(delta T)
(1)(450)(100-T) = (2)(4200)(T-20)
(450)(100-T) = (8400)(T-20)
45000 – 450T = 8400 T – 168000
45000 + 168000 = 8400 T + 450 T
213000 = 8850 T
T = 213000 : 8850
T = 24 ^oC
Suhu ʻO ka mahana hope loa o ka hui ʻana o ka hao wela a me ka wai anuanu ke noho nā mea ʻelua i ke kaulike wela he 24 ^oC.

2. Nīnau Hoʻokolohua Lahui SMA/MA Physics 2015/2016 Helu 20

Ua hui ʻia he 75 grama o ka wai ma ka mahana o 0 ^{° C me 50 grama o ka wai i hiki ai i ka mahana o ka hui ʻana he 40 °} C, no laila ʻo ka mahana mua o 50 grama o ka wai he...

A. 125 ^o C

B. 120 ^o C

C. 110 ^o C

D. 100 ^o C

E. 80 ^o C

Pahana

Ua ʻike ʻia:

Ka nui o ka wai 1 (m ₁ ) = 75 grams

Ka mahana mua o ka wai 1 (T ₁ ) = 0 ^o C

Ka nui o ka wai 2 (m ₂ ) = 50 grams

Ka mahana hope loa o ka hui ʻana (T) = 40 ^o C

Ua like nā anakahi o ka nuipa no laila ʻaʻole pono ka hoʻololi ʻana.

Makemake ʻia: Ka mahana mua o ka wai 2 (T ₂ )

Pane:

ʻŌlelo ke kumumanaʻo o Black i loko o kahi ʻōnaehana pani kaʻawale, ua like ka wela i hoʻokuʻu ʻia e kahi mea wela kiʻekiʻe me ka wela i omo ʻia e kahi mea wela haʻahaʻa.

Q _{i hoʻokuʻu ʻia} = Q _{i komo}

m ₁ c ( ΔT 1 ₎ = m ₂ c ( ΔT 2 ₎

Ua like ka wela kikoʻī o ka wai no laila ua hoʻopau ʻia ʻo c mai ka hoohalike.

m1 ( ΔT1 ) = _m2 ( ΔT2 _)​​_​​

(75)(40 – 0) = (50)(T ₂ – 40)

(75)(40) = (50)(T ₂ – 40)

3000 = 50 T ₂ – 2000

3000 + 2000 = 50 T ₂

5000 = 50 T ₂

T ₂ = 100

ʻO D ka pane pololei.

3. Nīnau Hoʻokolohua Lahui SMA/MA Physics 2015/2016 Helu 20

Ua hoʻomehana ʻia kahi metala 200 gram i 120 ^o C a laila hoʻokomo ʻia i loko o 100 gram o ka wai ma ka mahana o 30 ^o C. Ma hope o ke kaulike, lilo ka mahana o ka hui ʻana i 60 ^o C. Inā ʻo ka wela kikoʻī o ka wai he 4200 J.kg ^{-1 o} C ^-1 , a laila ʻo ka wela kikoʻī o ka metala...

A. 10,5 J.kg ^-1o C ^-1

B. 105 J.kg ^-1o C ^-1

C. 150 J.kg ^-1o C ^-1

D. 1050 J.kg ^-1o C ^-1

E. 1500 J.kg ^-1o C ^-1

Pahana

Ka hoʻololi ʻana o nā anakahi nuipa mai nā grama i nā kilograma (International System of Units)

Ua ʻike ʻia:

Ka nuipa hao (m1 ₎ = 200 grams = 0,2 kg

Mahana metala (T ₁ ) = 120 ^o C

Ka nui o ka wai (m2 ₎ = 100 grams = 0,1 kg

Mahana wai (T ₂ ) = 30 ^o C

Ka mahana hope loa o ka hui ʻana (T) = 60 ^o C

Ka wela kikoʻī o ka wai (c ₂ ) = 4200 J.kg ^{-1 o} C ^-1

Nīnau ʻia: Ka wela kikoʻī o ka metala (c ₁ )

Pane:

Q _{i hoʻokuʻu ʻia} = Q _{i komo}

m₁ c₁ (ΔT₁) = m₂ c₂ (ΔT₂)

(0,2)(c ₁ )(120 – 60) = (0,1)(4200)(60 – 30)

(0,2)(c ₁ )(60) = (0,1)(4200)(30)

12 c ₁ = 12600

c ₁ = 12600 / 12

c ₁ = 1050

ʻO D ka pane pololei.

4. Nā Nīnau Hoʻokolohua Lahui 2018 no ke Kula Kiʻekiʻe/Kula Kiʻekiʻe ʻOihana

Ua ninini ʻia he 250 ml o ka wai e paila ana (100 ^o C) i loko o kahi pā me 400 ml o ka wai ma ka mahana o 35 ^o C. Ma hope o ke kaulike wela, ʻo ka mahana o ka hui ʻana… (ka wela kikoʻī o ka wai 1,0 cal.gr ^-1 . ^o C ^-1 )

Pahana

Ua ʻike ʻia:

Mahana wai wela = 100 ^o C

Ka nui o ka wai wela = 250 ml = 0,25 lita = 0,25 dm³ ⁼ (0,25)(1000 cm³ ⁾ = 250 ^cm³

Mahana wai anuanu = 35 ^o C

Ka nui o ka wai anuanu = 400 ml = 0,4 lita = 0,4 dm³ ⁼ (0,4)(1000 cm³ ⁾ = 400 ^cm³

Ka wela kikoʻī o ka wai = 1,0 cal.gr ^-1 . ^o C ^-1

Ka nui o ka wai = 1 gr/ ^cm3

Nīnau ʻia: Mahana hui ʻana

Pane:

E helu i ke kaumaha o ka wai wela a me ke anuanu me ka hoʻohana ʻana i ke ʻano density:

m = ρ V

m = nuipa, ρ = nuipaʻa, V = nui

Ka nui o ka wai wela: m = ρ V = ( 1 gr/cm ³ )(250 cm ³ ) = 250 grams

Ka nui o ka wai anuanu: m = ρ V = ( 1 gr/cm ³ )(400 cm ³ ) = 400 grams

E helu i ka mahana o ka hui ʻana me ka hoʻohana ʻana i ke ʻano kumu o Black:

Ka wela i omo ʻia e ka wai anuanu = ka wela i hoʻokuʻu ʻia e ka wai wela

mc ΔT = mc ΔT

Ua like ka wela kikoʻī no laila ua hoʻopau ʻia ia mai ka hoohalike.

m ΔT = m ΔT

(400)(T-35) = (250)(100-T)

400T – 14000 = 25000 – 250T

400T + 250T = 25000 + 14000

650T = 39000

T = 39000 / 650

T = 60 ^° C