Describing the invisible properties of gas - Brian Bennett

Transcriber: tom carter Reviewer: Bedirhan Cinar

翻译人员: Yufei Wang 校对人员: Cho Lena

Every minute of every day,

生命中的每一个时刻

you breathe without even thinking about it.

你都在呼吸着空气

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

从你生命的开始到结束，你的身体自主地做着呼吸活动

You have muscles contract to bring oxygen, a gas,

通过肌肉的帮助，氧气（一种气体）进入你的肺

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

之后通过血液循环被交换到细胞

Gases are strange.

气体有些奇怪

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

我们看不到它们，但是凭借感觉我们知道它们就在那

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

我们能感受到风因为那是数以亿计的气体分子向我们撞击

And it feels good, right?

感觉不错吧？

Science is based on observation.

科学来源于观察

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

不幸的是，我们不能用肉眼观察到气体，因为它们太小了

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

我们需要利用其他感官来观察并得出结论

Observations are then compiled, and we create a model.

汇总整理我们的观察后，我们建立一个模型

No, not that kind of model.

不是图中的模型

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

科学家用模型来阐述物理现象的性质

First, gases always move in a straight line.

首先，气体通常沿直线运动

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

因为重力的作用，我们找不到能够准确描述它们的物体

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

想象从手枪中射出的子弹以同一速度沿完全直线运动

That would be like a gas molecule.

这就是气体分子的样子

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

第二，气体非常小，它们没有体积

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

作为一个整体，它们可以使气球膨胀起来，让你发现它们体积的变化

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

但是和其他形态的物体相比，单一气体是没有体积的

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

相比计算它们微乎其微的体积，我们选择把它们的体积简化为零

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

第三，如果气体分子之间发生碰撞，记住，这是假设

their energy remains constant.

它们的能量保持不变

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

一个简单的演示方法就是抛下一个绑有网球的足球

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

因为足球比网球大，所以足球的势能高

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

因此能量从大的足球转移到小的网球

and it flies away when that energy is transferred.

能量转移后，小球飞走了

The total energy stays the same.

所以总能量守恒

Gases work the same way.

气体的原理与此类似

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

一旦发生碰撞，小的气体微粒会加速，大的微粒则会减速

The total energy is constant.

总能量不变

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

第四，气体不会互相吸引，也不喜欢互相接触

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

但是记住第四点，他们在实际中确实会碰撞

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

最后，气体的能量和气温是成正比的

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

温度越高，气体所拥有的能量越多

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

有趣的是，在相同的温度下，所有气体拥有相同的能量

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

它们的能量和它们的类型无关，只和他们所处的温度有关

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

记住这是一个基于我们观察得出的气体微粒运动模型

gases always move in straight lines.

气体沿直线运动

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

它们很小，所以无法衡量单独个体

and they don't interact with one another.

并且它们之间没有接触

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

但如果它们撞上了对方，它们之间就会发生能量转换

and the total amount never changes.

总能量不会变化

Temperature has a major effect, and in fact,

事实上，温度对气体微粒的影响很大

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

处于同样温度的气体微粒有着相同的能量

Whew! I need to go catch my breath.

现在我要去休息一会了