## 字幕列表 影片播放

• Hey it's me Destin welcome back to Smarter Every Day. So you've probably observed

嘿，是我，Destin。歡迎回到Smarter Every Day。

• that cats almost always land on their feet. Today's question is why.

所以你可能已經發現貓咪幾乎總是用腳落地。

• Like most simple questions there's a very complex answer. For instance

今天的問題是為什麼？

• let me re-word this question. How does a cat go from feet up

就像是大部分的簡單問題一樣，這有個很複雜的答案。

• to feet down in a falling reference frame without violating

舉例來說... 所以讓我改寫一下這問題。

• the conservation of angular momentum. Now I've studied free falling bodies,

一隻貓如何在墜落過程的參考系統中

• my own in fact, in several different environments and once I get my angular rotation started

從四腳朝天轉變成腳朝下，而不違反角動量守恆定律？

• in one direction, I can't stop it. Today, we're gonna use a high speed camera, we're not

現在我已經研究過自由落體，實際上是以我自己，在幾種不同的環境之下做實驗，

• gonna use Alley, cause this is my daughter's cat, I don't want to hurt it. We're gonna use a stunt cat.

而一旦我讓角動量起始往某個方向，我停不下來。

• Let me introduce you to Gigi the stunt cat.

今天，我們要用一部高速攝影機，我們不會使用Alley，因為這是我女兒的貓咪。

• [music]

我不想弄傷牠。

• I'll just flip the video vertical, and then motion track

我們要使用一隻特技貓。

• the cat. It's just gonna take a lot more effort in post. We're gonna try to do

讓我向你介紹特技貓：Gigi。

• it in a way that doesn't make anybody mad. That's pretty hard to do.

我要把影像轉成垂直的，然後動態追蹤那貓咪。

• You've gotta drop a cat. Ready Gigi? Good.

只是要費更大的勁在後製上。

• Checking out the high speed data there Gigi?

我們要試著以不讓任何人生氣的方式來做這件事。那很難。

• [music]

我要丟一隻貓。

• OK the first thing a cat does when it's falling is try to figure out which way is up.

準備好了嗎，Gigi？

• It does this either with a gyro in the ear, or with it's eyes.

很好。

• 3..2..

妳在檢查那兒的高速資料嗎，Gigi？

• Ready to talk cat physics? Alright, so check out this footage I captured with the Phantom Miro

好，一隻貓在墜落過程中所做的第一件事是嘗試去分出上下。

• while Gigi goes to get a drink of water. So here's what's interesting about this to me. If you'll notice

牠要不是用耳朵中的陀螺儀(內耳半規管)，要不就是用眼睛，來做這件事。

• at the beginning of the drop the cat is not rotating. Half way through the drop

3… 2…

• the cat is rotating, and then at the very end Gigi somehow stops rotating.

準備好談談貓咪物理學了嗎？

• Newton's first law says that an object at rest will stay at rest unless acted

好吧，那麼趁Gigi去喝水的時候，看看這段用Phantom Miro(攝影機型號)所捕捉到的影片。

• on by an external force. I see no external forces on this cat.

所以這個是讓我感到興趣的東西。如果你注意到在墜落過程的開端，貓咪並沒有轉動。

• So what's happening here? It's not making sense to me. OK so in order to

掉到一半的時候貓咪才轉動，然後最後Gigi用某種方式停止轉動。

• really get the right data, we're gonna have to drop her 90 degrees out of phase. Ready girl?

牛頓第一定律說一個靜止物體將保持靜止除非接觸到一個外在力量。

• This time watch her tail. 3.. 2.. 1..

我在這貓咪身上沒看到外在力量。所以這裡發生什麼事？

• [music]

對我來說一點道理也沒有。

• OK so you think you've figured it out? Check this out.

好的，所以為了要真正得到正確的資料，我們必須要把她反轉90度丟下。

• You probably noticed that when the cat was falling, her tail was rotating in the

好了嗎，女孩？這次注意她的尾巴。3… 2… 1…

• direction opposite of where her body was rotating. What's interesting about that

好的，所以你以為你已經搞清楚了？來看看吧。

• is that that's not how it works. In fact even Bobtail cats

你也許注意到當貓咪在墜落時，

• can do this. It's called the cat righting reflex. I'll prove it to you.

她的尾巴會以一個和身體轉動相反的方向轉動。

• I came across some video from the 60s when the air force was researching micro gravity for

有趣的是，那不是它的運作方式。

• future astronauts. Turns out they took some cats up on parabolic flights.

事實上，甚至連短尾貓也可以這樣做。它叫做貓咪翻正反射(一種貓的本能)。

• He tries to rotate his tail to flip over but it doesn't work. He just ends up

我會證明給你看。

• nutating wildly. Then he does something interesting. He takes his back

我發現一些60年代的影片，當空軍為了未來的太空人在做微引力研究時。

• and he bends it, and when he bends his back and then creates motion, something interesting happens.

結果他們帶了一些貓咪上去無重力飛行。他試著轉動他的尾巴去翻身，但沒有用。

• Aah. Now we're getting somewhere. So let me

他只是變得失去控制地下墜。

• show you one more cat flip with the Miro and we'll figure this out.

然後他做了件有趣的事情。

• OK the arched back ends up being pretty

他拱起背部，

• important. What he does is he divides his body up into two separate rotational

然後當他拱起背部然後做出動作，有趣的事情發生了。

• axes that are tilted from one another. When he's released he pulls his front paws in

啊，現在我們有點頭緒了。

• and does the ice skater trick. He decreases his moment of inertia in the front so he can spin

所以讓我用Miro再展示一次貓的翻轉給你看，然後我們會找出答案。

• fast up there, but in the back he pushes his legs away from him, increasing his moment

好，拱起的身體看來是很重要的。

• of inertia, so a really large twist in the front equals a really small

他所做的是把身體分成兩個分開且互相傾斜的旋轉軸。

• twist in the back in the opposite direction and the torques equal out. So as soon as

當他被放開時，他收起前爪，然後使出冰上曲棍球的招式。

• he gets his front paws in under him, all he has to do is extend those legs back out to

他降低前方的轉動慣量以使他能夠在上面快速轉動，

• increase that moment of intertia and stop the front twist, and extend his back

但他在後面踢腿，增加他的轉動慣量，

• legs along that rear axis. That allows him to twist those around

所以前方非常強力的扭動等同於是後方很小力、相反方向的扭動，而力矩互相抵消。

• really fast, and then all he has to do is pull them back in under his body and then extend

所以一旦他將前爪收到身體下面，他所要做的只是將腿伸展回

• all four legs and brace for impact.

去增加轉動慣量並停止前半身轉動，然後沿著後方軸線伸展他的腿。

• [music]

那讓他能夠非常快速的扭轉，然後他所要做的只是將它們收回身體下方

• So thank you for your attention. I hope you learned something

並伸展全部的四條腿並為衝擊做準備。

• pretty cool about cats. If you don't mind.. [Angry meowing] Ooh! OK OK I'm done!

所以謝謝觀賞。我希望你學到了一些關於貓咪很酷的事情。

• If you would, go check out your other cat videos after trying

如果你不介意…噢！好 好 我弄完了！

• to catch Gigi. Wooh! A little too rowdy. If you'd like to, click Gigi

如果你想，抓到Gigi後去看看其他的貓咪影片。

• the cat to subscribe, we'd appreciate it. I hope you had a good one. And aah

哇！有點太粗暴了。

• Get the ball! You gotta catch her first. I got it, you want it?

如果你願意，按一下Gigi貓來訂閱，我們會很感激。

• Look... Very cool cat.

希望你喜歡這影片。還有啊…撿球！!

• She let us drop her hundreds of times. Or, you know, maybe just 5.

你得先抓到她。

• Want your ball? Go get it!

我撿到球了，妳想要嗎？

• Click her if you want to subscribe, but right now we're playing fetch.

看...很酷的貓咪。

她讓我們丟了幾百次。或，你知道，也許只有5次。

• I'm Destin. You're getting Smarter Every Day. Have a good one.

想要你的球嗎？去撿吧！

• [Whispered] There you go.

如果你想訂閱請點她，但現在我們在玩撿球遊戲。

• You earned it.

準備好了？去撿吧！

• Let me explain why cats are

我是Destin。你每天都變得更聰明。掰掰。

• wizards at physics. First of all they have physiology working for them. They have no working clavicle

那就對了。

• like I do, and secondly they have very flexible back bones.

那就對了。你應得的。

• The talent needs a break.

讓我解釋為何貓咪是物理界的魔術師。

• 30 centimeters or higher. Anything below that is unsafe.

首先，他們有適用的生理構造。

• Not that we condone dropping cats. C'mere!

他們沒有像我一樣有作用的鎖骨，而且第二，他們有非常有彈性的背骨。

• C'mere.. There you go. Go get in the catapult.

小天才需要休息。

• 3.. 2.. 1.. Oh man.

30公分或更高。任何比那低的高度都不安全。

• [ Captions by Andrew Jackson ] captionsbyandrew.wordpress.com

不是我們在容許丟貓咪。

來！過來.. 這就對了。

Hey it's me Destin welcome back to Smarter Every Day. So you've probably observed

# 慢速解析從天而降的貓如何翻轉（High Speed Video of Flipping Cats | Smarter Every Day 58 (Cute Cat vs Physics)）

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VoiceTube 發佈於 2012 年 12 月 12 日