Describing the invisible properties of gas - Brian Bennett

Transcriber: tom carter Reviewer: Bedirhan Cinar

譯者: Allen Li 審譯者: Jephian Lin

Every minute of every day,

每一天的每一分鐘

you breathe without even thinking about it.

你都在呼吸，連想都不用想

Your body does it on its own, from the day you're born until the day you die.

身體會自主呼吸，從你出生到死亡

You have muscles contract to bring oxygen, a gas,

肌肉收縮以吸入氧，一種氣體

into your lungs, which is then transferred by your bloodstream to every cell in your body.

到肺部再由血液運到身體的每個細胞

Gases are strange.

氣體很奇怪

We can't see them, but we know they're there because we can feel them.

我們看不到，但我們知道它存在因為我們感覺得到

What we experience as wind is really trillions and trillions of gas molecules slamming into your body.

我們感覺到的風 其實是數以兆計的氣體分子在撞擊你的身體

And it feels good, right?

而且感覺不錯，對吧？

Science is based on observation.

科學的基礎是觀察

Unfortunately, we cannot observe gases with our eyes -- they're too small.

不幸的是，我們的眼睛觀察不到氣體 ——它們太小了

We have to use our other senses to make observations and draw conclusions.

我們得用其他感官進行觀察並得出結論

Observations are then compiled, and we create a model.

觀察、收集資料、建立模型

No, not that kind of model.

不，不是那種模型

A model is a way scientists describe the properties of physical phenomena.

模型是科學家描述物理現象的一種方式

First, gases always move in a straight line.

第一點、氣體分子總是直線運動

We don't really have anything to demonstrate this with because gravity always pulls objects down.

沒辦法示範這點因為重力一直把物體往下拉

So imagine a bullet fired from a gun, and that bullet goes on at a constant speed in a perfectly straight line.

想像從槍射出的子彈 而子彈以等速依直線前進

That would be like a gas molecule.

這就像氣體分子

Second, gases are so small, they occupy no volume on their own.

第二、氣體非常小，本身不佔體積

As a group they do, blow up any balloon and you can see how that volume changes.

一群氣體分子就可以撐大氣球 而你可以看到體積的改變

But single gases have no volume compared to other forms of matter.

與其他形態的物質相比 單一氣體分子幾乎不佔體積

Rather than calculating such a small amount of matter, we just call it zero for simplicity.

與其計算這麼小量的物質 簡單起見不如說它是零

Third, if gas molecules collide, and they do -- remember, these are assumptions --

第三、如果氣體分子碰撞，的確 ——記住，這些都是假設——

their energy remains constant.

氣體的能量會保持不變

An easy way to demonstrate this is by dropping a soccer ball with a tennis ball balanced on top.

有個簡單的證明方法是 把網球平衡放在足球上一起掉落

Because the soccer ball is bigger, it has more potential energy,

因為足球比較大，位能較多

and the energy from the larger ball is transferred to the smaller tennis ball

大足球的能量傳到小網球

and it flies away when that energy is transferred.

能量轉移後，網球就彈飛了

The total energy stays the same.

總能量保持不變

Gases work the same way.

氣體的情形也一樣

If they collide, smaller particles will speed up, larger particles will slow down.

大小粒子相撞時 小粒子變快，大粒子變慢

The total energy is constant.

總能量保持不變

Fourth, gases do not attract one another, and they don't like to touch.

第四、氣體分子不會互相吸引 它們不喜歡碰撞

But remember rule three. In reality, they do collide.

但請記住規則三 在現實中，氣體分子會碰撞

Finally, gases have energy that is proportional to the temperature.

最後，氣體能量與溫度成正比

The higher the temperature, the higher the energy the gases have.

溫度越高，氣體能量越高

The crazy thing is that at the same temperature, all gases have the same energy.

不可思議的是，相同溫度下所有氣體的能量都相同

It doesn't depend on the type of gas, just the temperature that gas is at.

與氣體種類無關，只與氣體溫度有關

Keep in mind this is a model for the way gas particles behave, and based on our observations,

請記住，這是基於觀察產生的 氣體分子行為模型

gases always move in straight lines.

氣體分子總是直線運動

They're so small, that they're not measurable on their own,

本身小到不必計算

and they don't interact with one another.

彼此之間沒有交互作用

But if they do bump into one another, that energy is transferred from one particle to another,

但相撞時，能量由一個分子轉移到另一個

and the total amount never changes.

總能量不變

Temperature has a major effect, and in fact,

溫度影響很大，事實上

all gases at the same temperature have the same average energy.

在相同溫度任何氣體的平均能量都相同

Whew! I need to go catch my breath.

呼！我要去喘口「氣」了