沙文

回復 431# 抽刀斷水

咁我除衫先玩都係仿效自然界既遊樂方式啫

抽刀斷水

自然分娩係指仿效自然界既分娩方式咁解既。

沙文

回復 429# 抽刀斷水

咁女人生仔又夠要除褲，邊鬼度有「自然分娩」？

抽刀斷水

都幾人為架，至少烏龜伉儷唔駛除衫，沙文伉儷就要除衫。

沙文

回復 427# 抽刀斷水

烏龜先生同太太咁玩，係自然

難道我又玩同一個遊戲就是人為？

抽刀斷水

根據定義，自然和人為是對立的，人為的就是非自然。

因此，你叫人去幫你剪頭髮，斷唔會被稱為自然脫髮既。

沙文

影相發燒友參加攝影比賽，題目係「大自然」
我的拍友影這張相參賽：


我不想重複他的作品，於是我這張相參賽:



但係連參加都參加唔到。報名處的小姐話我離題

點解雀仔築巢就自然，人起間屋就唔自然呢？

沙文

回復 424# dye
Thx dye, your explaination seems make more sense 2 me.
但為了慎重起見, 我仍會在滿月宴上進行該項實驗

dye

Are you sure the electric heating element of the hair dryer will "burn" any oxygen away?  How about a safer way with air from freezer, or air from top of a block of ice?  If temperature is an issue, cooler air should be able to do it better, right?

Actually I found an even more likely answer, it fits with all observations I seen so far in my life:

I think the wind blow the chain reaction of the fire away.  In order for the flame to continue, the last reaction must be in proximity with the next reaction in order to transfer the heat.  

With the air moving so fast, it outpace the reaction front.

This is observable as the wind gets stronger and stronger, the flame moves away from the head.  At certain wind speed, the flame will bound to be too far from the fuel source.

**  I think the temperature idea is correct only concerning candle because of the way the fuel is supplied (vapourization of the wax).  It is incorrect in the general sense.

抽刀斷水

根據http://www.tutorvista.com/conten ... sion/combustion.php，燃燒的conditions如下：
1. 物質本身可燃
2. 氧氣
3. 溫度

那吹氣令其熄滅，究竟是令溫度下降是主因，抑或令氧氣的密度降低（降低氣壓）呢？

我猜用風筒吹，經過風筒發熱線後，部分氧氣就會燃燒走，所以沙文的實驗方法是有問題的。

最好是：

用一個氧氣筒，將氧氣加熱後向火柴或蠟燭噴出，咁就perfect喇！（不過實驗危險性高，建議沙文先立遺囑，到自己活得不耐煩時才進行）

dye

Sorry, I do not believe what the web site is saying.

Here is an experiment Sherman can do and help us understand the question:

Place the candle further and further away from the hair blower and see the effect.  (Test the air pressure.  The further the wind source, the smaller the low pressure.)

Use this distance, change the temerature of the wind blowing, perhaps by using the fridge and heating element of the dair dryer.  (Test for temperature.  Is it true that people in Arctic has an easier time blowing out candle than say, African?)

Lastly, to proof what the web site is correct, it should be impossible to blow out a lighter because you can't "blow off" the flame.  So change the fire source and try it again to see if there is any difference!

This is dye again,

I find this, see if it helps

http://www.newton.dep.anl.gov/askasci/gen01/gen01405.htm

This is dye at your service.

I am not perfectly certain but here is what I think:

1) Fire burns better under breeze because it brings in oxygen and carries the carbon dioxide away.

2) In a strong wind, the negative pressure create a vaccum sucking both oxygen as much as carbon away.  (To have wind blowing, you create a low pressure zone around/near the fire.)

It has nothing to with temperature, although temperature is an intial require condition for the ignition.  

(Notice how ignition is different from the process of burning.  It is NOT ignition that Sherman is asking, it is burning.  If the fire is already burning, is the flow of air enough to carry so much heat away to below the ignition point?)

沙文

回復 418# 抽刀斷水

我依然覺得您好似我依然覺得您好似


我試過用風筒熱風吹火柴都吹得熄

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回復 417# 沙文


    咁易咩，要做論文架：
http://iafss.haifire.com/html/ao ... abstracts/1-380.htm

仲有，係磷燒火藥，火藥燒木先真。

沙文

回復 415# 抽刀斷水

燒完磷之後就燒木。我等佢燒木時吹熄佢，您話我聽木嘅ignition point係幾多嘞

豬丫痾腎

或者咁講，吹得熄係因為熱既空氣粒子被吹散左，而唔係直接降低粒子既溫度。
溫度計係固體冇得被風吹散。

抽刀斷水

氣溫 -13° C姐，但係點火柴既過程，藉由火柴頭的火藥磨擦，火柴頭包含火藥和磷，磷的燃點很低，磨擦就足以起火，磷燃燒後會燒著火藥，再把火柴木枝升溫，那部分就再不是 -13° C了。

自己睇下，無點你：
http://en.wikipedia.org/wiki/Match

沙文

我頭先又試過，我懷疑您的解釋同創世紀的性質一樣。

我在 -13° C温度之中點火柴，都點得著。您點吹，都吹唔到支温度計低過-13°卦？

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回復 412# 沙文


    兩支溫度計先放在熱水中，一支你狂吹，一支放係度唔理，睇下邊支快Ｄ降溫咪知囉。

我就無探熱針、溫度計，我地Ｄ先進家庭，梗係用高科技野啦：