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麥精 2007-01-08 19:22

F.3 Physics (urgent)

我想問幾條問題..........係想問點解...所以唔該比個STEP我

1. 點解condensation occurs at any temperature?

2. An immersion heater of power 200W can boil away a liquid of boiling point of 80°C at a rate of 1.6 x 10^-4 kg s^-1 . Assuming all the energy given out by the heater is absorbed by the liquid, find the specific latent heat of vaporization of the liquid.

3. Ice cubes of 25g at 0°C are dropped into a beaker containing 250g of water at 40°C. What is the final temperature of the mixture? Assume no energy is lost to the surroundings.

4. When 0.3kg of ice at 0°C mixes with 1kg of water at 20°C, what is the final mixture?

麥精 2007-01-08 19:44
someone help me?

BBF 2007-01-08 20:31
唔記得晒
不過我當年係中4先學...

麥精 2007-01-08 20:39
仲有冇人幫我呀 聽日考

豬脾 2007-01-08 20:44
琴年學左,specific heat+ specific latent heat~~,,,不過
d step 唔記得哂


第一題做咩架 唔識

Mr-Brian 2007-01-08 20:46
今日先考完,

BBF 2007-01-08 20:47
It should be easy, just use the formula,
but need to change the unit of temp "from °C to K"
specific latent heat also need to consider.

麥精 2007-01-08 20:50
死啦...我搞到好覆雜呀.........

迪神 2007-01-08 20:52
咪住!!!!!!!!!


第二題係搵latent heat呀~~~~~~

jov 2007-01-08 20:53
4. When 0.3kg of ice at 0°C mixes with 1kg of water at 20°C, what is the final mixture?

0.3latent heat of fusion+0.3 X capacity of water X T=1 X capacity of water X(20-T)

好似係咁

麥精 2007-01-08 20:53
引用第8樓迪神於2007-01-08 20:52發表的“”:
咪住!!!!!!!!!
第二題係搵latent heat呀~~~~~~ [表情]


所以我先唔識

迪神 2007-01-08 20:54
引用第10樓麥精於2007-01-08 20:53發表的“”:
所以我先唔識 [表情]

latent heat條式又係乜野?

Mr-Brian 2007-01-08 20:55
係時候啦

Mr-Brian 2007-01-08 20:58
有冇答案?我唔confirm岩唔岩

麥精 2007-01-08 21:00
引用第11樓迪神於2007-01-08 20:54發表的“”:
latent heat條式又係乜野? [表情]


SPECIFIC就有

l=E/m

Mr-Brian 2007-01-08 21:01
引用第14樓麥精於2007-01-08 21:00發表的“”:
SPECIFIC就有 [表情]
l=E/m

有冇答案?我識但係我唔confirm岩唔岩

麥精 2007-01-08 21:01
引用第13樓abbrian2005於2007-01-08 20:58發表的“”:
有冇答案?我唔confirm岩唔岩


2. 1.25 x 10^6 J kg^-1
3. 29.1°C
4. A mixture of ice and water at 0°C

BBF 2007-01-08 21:03
http://hk.knowledge.yahoo.com/question/?qid=7006102104272

similar question, with answer, for your ref.

ice + water => 0°C

麥精 2007-01-08 21:09
引用第17樓ballballfull於2007-01-08 21:03發表的“”:
http://hk.knowledge.yahoo.com/question/?qid=7006102104272
similar question, with answer, for your ref.
ice + water => 0°C


呢條J3教了我

BUT ALSO THX VERY MUCH

jov 2007-01-08 21:12
del

豬脾 2007-01-08 21:18
有冇人識第一題
我都想知

麥精 2007-01-08 21:21
引用第20樓卡卡....於2007-01-08 21:18發表的“”:
有冇人識第一題
我都想知 [表情]


我都唔明呀.....我阿爸話EVAPORATION係因為有D野可以<100度都得
(條題本來問EVAPORATION同CONDENSATION有咩一樣...)但係佢都唔係CONDENSATION..

Mr-Brian 2007-01-08 21:32
第3題差少少

麥精 2007-01-08 21:34
引用第22樓abbrian2005於2007-01-08 21:32發表的“”:
第3題差少少
[表情]


1,2呢?

識既POST左先啦

THX

等陣比番D好友元你

jov 2007-01-08 21:34
energy of 250g of water at 40°C = energy of Ice cubes of 25g at 0°C

0.25 x capacity of water X(40-T)=0.025xlatent heat of fusion+0.025x capacity of water xT

0.25 x 4200 X(40-T) = 0.025x3.34x10^5+0.025x4200xT

42000-1050T=8350+105T

T=29.1°C

Mr-Brian 2007-01-08 21:36
引用第23樓麥精於2007-01-08 21:34發表的“”:
1,2呢? [表情]
識既POST左先啦 [表情] [表情] [表情]
.......

1完全唔識

豬脾 2007-01-08 21:36
引用第21樓麥精於2007-01-08 21:21發表的“”:
我都唔明呀.....我阿爸話EVAPORATION係因為有D野可以<100度都得
(條題本來問EVAPORATION同CONDENSATION有咩一樣...)但係佢都唔係CONDENSATION..

等我估下先^_^係關convection 事既

麥精 2007-01-08 21:37
引用第25樓abbrian2005於2007-01-08 21:36發表的“”:
1完全唔識


2?

Mr-Brian 2007-01-08 21:38
引用第24樓ｊ摩連奴．狂妄於2007-01-08 21:34發表的“”:
energy of 250g of water at 40°C = energy of Ice cubes of 25g at 0°C
0.25 x capacity of water X(40-T)=0.025xlatent heat of fusion+0.025x capacity of water xT
0.25 x 4200 X(40-T) = 0.025x3.34x10^5+0.025x4200xT
.......

latent heat of fusion
我就係差E個...

Mr-Brian 2007-01-08 21:40
引用第27樓麥精於2007-01-08 21:37發表的“”:
2? [表情]

冇時間同埋mass

Mr-Brian 2007-01-08 21:42
引用第14樓麥精於2007-01-08 21:00發表的“”:
SPECIFIC就有 [表情]
l=E/m

e個係Latent heat of fussion

Mr-Brian 2007-01-08 21:44
係咪d liquid轉哂做GAS?

Mr-Brian 2007-01-08 21:46
去左邊?

麥精 2007-01-08 21:49
MOUSE SHORT JOR

D YEH DIU CHUN SAI

jov 2007-01-08 21:49
2. An immersion heater of power 200W can boil away a liquid of boiling point of 80°C at a rate of 1.6 x 10^-4 kg s^-1 . Assuming all the energy given out by the heater is absorbed by the liquid, find the specific latent heat of vaporization of the liquid.


1.6 x 10^-4 x lv=200

lv=1250000

Mr-Brian 2007-01-08 21:52
引用第34樓ｊ摩連奴．狂妄於2007-01-08 21:49發表的“”:
2. An immersion heater of power 200W can boil away a liquid of boiling point of 80°C at a rate of 1.6 x 10^-4 kg s^-1 . Assuming all the energy given out by the heater is absorbed by the liquid, find the specific latent heat of vaporization of the liquid.
1.6 x 10^-4 x lv=200
.......

點解?

麥精 2007-01-08 21:52
WT IS lv?

jov 2007-01-08 21:53
引用第35樓abbrian2005於2007-01-08 21:52發表的“”:
點解?

Energy=mass x latent heat of vapouration

Energy=Power X Time

jov 2007-01-08 21:54
引用第36樓麥精於2007-01-08 21:52發表的“”:
WT IS lv?

latent heat of vapouration

Mr-Brian 2007-01-08 21:54
引用第37樓ｊ摩連奴．狂妄於2007-01-08 21:53發表的“”:
Energy=mass x latent heat of vapouration
Energy=Power X Time

E=Mc Delta T wor

jov 2007-01-08 21:55
Energy=mass x latent heat of vapouration

Energy=Power X Time

Power X Time=mass x latent heat of vapouration

200 X 1=1.6 x 10^-4 x lv

lv=1250000

jov 2007-01-08 21:56
引用第39樓abbrian2005於2007-01-08 21:54發表的“”:
E=Mc Delta T wor

岩..不過依度溫度冇變..何來Delta T

Mr-Brian 2007-01-08 21:57
引用第40樓ｊ摩連奴．狂妄於2007-01-08 21:55發表的“”:
Energy=mass x latent heat of vapouration
Energy=Power X Time
Power X Time=mass x latent heat of vapouration
.......

TIME =1?

迪神 2007-01-08 21:57
我諗既方法岩架，係唔識計ja~

jov 2007-01-08 21:57
引用第42樓abbrian2005於2007-01-08 21:57發表的“”:
TIME =1?

a rate of 1.6 x 10^-4 kg s^-1

per second嘛

Mr-Brian 2007-01-08 21:58
引用第44樓ｊ摩連奴．狂妄於2007-01-08 21:57發表的“”:
a rate of 1.6 x 10^-4 kg s^-1
per second嘛

Mr-Brian 2007-01-08 21:58
在下服哂

jov 2007-01-08 21:59
boil away a liquid of boiling point of 80°C at a rate of 1.6 x 10^-4 kg s^-1

即係一秒入面有1.6 x 10^-4 kg既liquid變左蒸氣

Mr-Brian 2007-01-08 22:00
引用第47樓ｊ摩連奴．狂妄於2007-01-08 21:59發表的“”:
boil away a liquid of boiling point of 80°C at a rate of 1.6 x 10^-4 kg s^-1
即係一秒入面有1.6 x 10^-4 kg既liquid變左蒸氣

冇睇單位

麥精 2007-01-08 22:01
波波夫,J3,ABBRIAN,迪神洗唔洗要我D心意?


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