And the Saturn V rocket that launched people to the moon had a thrust of 33,360,000 newtons

噴射引擎推力的世界紀錄則是57萬牛頓

But how can we measure forces this big accurately?

載人登月計畫使用的土星五號火箭推力高達3千3百萬牛頓

Well, we need to ask this guy.

話說回來，這麼大的力量我們是如何精確測量出來的呢？

Hi my name is Rick Seifarth I'm a physical scientist in the Mass and Force Group.

這個問題讓我們找個專家來回答

Am I supposed to look at the camera?

大家好，我叫Rick Seifarth，我是國家標準技術研究所(NIST)的物理學家

Sure.

我應該要看著鏡頭講話吧？

Okay.

不然呢？

You can look at anything you like.

好吧！

Rick manages a dead weight machine that can apply 4,448,222 newtons.

隨便你想看哪裡啦！(哈哈)

Why such a strange number? Because that's exactly equal to 1,000,000 pounds of force.

Rick負責管理一台靜荷重設備，可提供高達4,448,222牛頓的力

There are twenty fifty thousand pound increments in this machine

為什麼會是這個怪怪的數字？因為它剛好等於1百萬磅的力

20 times 50 equals 1,000,000 pounds.

這台機器裡面有20個50,000磅重的砝碼

Cumulatively that's 4.45 mega newton.

20 x 5,0000磅 = 1,000,000磅

Elsewhere in the world, are there larger masses that people have calibrated?

累計起來就是約445萬牛頓

I ask that question to every visitor we get and I've not gotten..

這世界上有沒有其他人曾校準過比你們這裡更大重量的砝碼？

one response that says: yeah I know where bigger stuff is calibrated.

這個問題我問過每一位參觀來賓，目前還沒有得到一個回答是：

So if I really want to go out on a limb and brag I'll say

"有啊！真的有人校準過更大的東西！"

these are the largest mass objects ever calibrated.

所以如果我真的想要出去大肆吹噓的話

Anywhere

我敢說這些絕對是迄今被校準過的最大砝碼

The machine works like this, below ground are the 20 carefully calibrated masses.

全世界最大的

Their weight is used to calibrate force sensors also called

這機器的工作原理如下：在地面以下有20個經校準的砝碼

Force Transducers, in the lab upstairs.

它們的重量被用來校準位於實驗室樓上的"力傳感器" (Force Transducer)

This is a one million pound capacity 4.45 mega newton,

這個"力傳感器"可測到1百萬磅，相當於445萬牛頓

and this is 13.3 mega newtons, three million pounds force.

這個則可以測到3百萬磅，相當於1,335萬牛頓的力

This is the biggest machine of it's type in the world, and obviously one of a kind.

這台機器是這世界上同類型中最大的一台 ，所以顯然是獨一無二的

One of these,

其中之一，

will be placed on the compression head right here.

將被放置在這裡的重壓台上

Then, a hydraulic ram in the attic starts to raise the green lifting frame

然後，在閣樓上的液壓油缸開始拉起 綠色升降架

And once the force transducer contacts the red loading frame,

當"力傳感器"接觸到紅色負載架時

well then it starts lifting the weights downstairs.

它就開始拉動樓下的砝碼

And as the lifting frame continues to rise, more and more of the

隨著升降架繼續上升，越來越多的

50,000 pound weights become suspended by the force sensor.

50000磅砝碼被"力傳感器"懸吊起來

And since the weights create an accurately-known force,

由於這些砝碼提供了精確的已知力

the readouts from the force transducer can be precisely calibrated.

就可以用來精密地校準當下"力傳感器"的讀數

These devices are then sent out into the field.

然後，這些已校準的"力傳感器"就可以送到現場使用。

Well literally, there's a test stand that's set up with one of these gizmos-

舉例來說，有一種試驗台就有使用"力傳感器"這個元件

a force transducers - embedded in the test stand somewhere.

它被嵌入在試驗台的某處

And so the rocket is fired up, perhaps ramped up, ramped down and those forces are monitored.

當火箭被發動時，不論是逐步加速或減速，過程中的推力值都可以被監控

You know, in the old movies you'd hear: "go to 104% of power." Well, how do they know it's 104% of power?

你在電影某幕中可能會聽到指令：“推力設定104％”，那麼他們是如何確定它真是104％？

Because somebody's measured it somewhere.

那是因為某處有人正在測量它

When it comes to minimizing uncertainty, these guys aren't messing around.

當談到盡量降低不確定性，這些傢伙可沒有掉以輕心

This piece right here is approximately 50,036.27 pounds of mass.

這裡的一塊砝碼重量約為50,036.27磅

Approximately.

只是大約？

Approximately, yes! [laughter]

就是大約！ [笑聲]

Think about that for a moment.

讓我們停下來思考一下

Each of these pieces has a mass equivalent to ten minivans,

這些砝碼中旳每一個重量都相當於10台休旅車

and their exact value is known to within several American nickels.

而它們的重量誤差值卻只相當於幾枚五分錢硬幣

Just a few American nickels worth of difference?

只有幾枚五分錢硬幣的差異？？

Yeah.

沒錯！

That tiny uncertainty is measured with respect to the very definition of the kilogram

對於這樣微小不確定性的測定是基於千克的定義："K20"原型

using K20 - that's the United States fundamental mass standard.

這是美國的基本質量1千克標準品

This is done by comparing combinations of known weights, starting with K20, with larger unknown weights,

這是通過從1千克(K20)開始的已知砝碼組合，和其他較大未知砝碼相比較來完成

gradually working up to larger and larger masses.

逐步往上到越來越大重量的砝碼

For example, here a single 5-kilogram mass is compared to two 2s and a 1.

例如，這裡有一個5千克的砝碼正在與一組由兩個2千克和一個1千克砝碼的組合來相比較

At some point in this process, they convert and start working in pounds, going from 50-pound masses to 500 pounds,

在這過程中的某些階段，它們的單位將開始由千克轉換為磅，然後從50磅重的砝碼進行到500磅

and then 2500 pounds. And then, using a scale in the floor, to reach 10,000 pounds and then 20,000,

再來到2,500磅。然後轉到落地型的大型磅秤，以達到10,000磅、20,000磅、

and finally 30,000 pounds.

最終達到30,000磅

Combinations of these huge weights are then used to calibrate the 50,000-pound masses which form the weight stack.

然後再用這些巨大的砝碼的組合來校準這些將用作於配重片的50,000磅砝碼

And we have to have that, because what we sell is the vertical force vector that's generated by these weights

我們必須不厭其煩，因為這就是我們提供的服務：由這些配重片懸在重力場中所產生的精準垂直力矢量

hanging in a gravitational field. We sell that with an uncertainty attached to it of 0.0005%,

我們服務的價值在於誤差只有0.0005％的精確度

five parts per million, so that means at full one million pounds of applied force, we guarantee that to be accurate - if you will -

百萬分之五的誤差，意謂著在100萬磅的推力量測裡，如果你能接受5磅以內的不確定性，

within five pounds.

我們可以保證數值的準確性

Not only does that mean the masses have to be accurately calibrated,

然而，這不僅僅代表著這些配重片必需被精密地校準

it also means the gravitational acceleration at this location has to be taken into account.

同時這也代表必須考慮到所在位置的重力加速度

It's actually slightly less than Earth's standard gravity, so an additional 600 pounds are required.

因為所在地的地心引力實際上略小於地球的標準引力，因此需要補足額外的600磅重

Plus, the buoyant force must be counteracted,

除此之外，還有空氣浮力必須被抵消

since these masses displace 125 pounds of air,

因為這些配重片的體積所排除的空氣量為125磅 (產生125磅的浮力)

a further 125 pounds must be added to reach a million pounds of force.

因此必須再加上125磅才能真正補足100萬磅的力

What strikes me as kind of amazing is that, like, this machine needs to exist, in a way.

想到這台機器在某些方面上存在的必要性，讓我感到驚奇不已

When I would have thought about it, like how would Boeing measure its forces, I would have thought

我曾好奇波音公司如何測量它的引擎推力量，我真有想過這事

OK, they just, you know, calibrate a device that works up to X but then they can, you know,

他們也就只是依樣校準到若干個配重片

generalize. Well, generalize - you know what I mean, like - Yes!

概括化。那麼，概括化 - 你知道我的意思，就像 - 是的！

There's an axiom that says "one physical test is worth a thousand expert opinions."

有句至理名言：“一個物理測試抵得上一千名專家的意見”

And that has proven itself time and again, particularly in the world of physical testing.

這句話經得起千錘百煉，尤其是在物理測試的領域

If you're getting on an airplane that somebody has built, are you willing to accept a 10% uncertainty on these numbers

如果某人建造了一架飛機，它建造過程中的量測不確定性達到10%，你會敢坐嗎？

or do you want it to be - the uncertainty on these measurements to be down in the mud?

或者你希望這些測量的不確定性能夠低到仆街？