Hey it’s me Destin
欢迎回到Smarter Every Day
Welcome back to SmarterEveryDay
So you’ve probably observed that cats
almost always land on their feet
Today’s question is why.
Like most simple questions there’s a very complex answer
For instance let me reword this question
How does a cat go from feet up
To feet down
In a falling reference frame without violating the conservation of angular momentum
Now I’ve studied free falling bodies, my own in fact
in several different environments and once i get my angular rotation started
in one direction, I can’t stop it.
今天 我们将用到一个高速摄像机记录 我们不会用艾利做实验
Today, we’re going to use a high speed camera- we’re not going to use Alley
because this is my daughter’s cat, i don’t want to hurt it-
we’re going to use a stunt cat
let me introduce you to Gi-Gi
the stunt cat
I’ll just flip the uh, the video vertical
and then motion track the cat
it’s just going to take a lot more effort in post
We’re going to try to do it in a way that doesn’t make anybody mad
That’s pretty hard to do.
You gotta drop the cat
Checking out the high speed data there Gi-Gi?
好的 当猫下落的时候 它做的第一件事就是试图分清
Ok the first thing a cat does when it’s falling is try to figure out
which way is up.
It does this either with the gyro in the ear
or with its eyes
Ready to talk cat physics?
我们来看一下这个 我用 Phantom Miro相机拍摄的连续镜头
Alright. So check out this footage i captured with the Phantom Miro
While Gi-Gi goes to get a drink of water.
So here’s what’s interesting about this to me.
You’ll notice that at the beginning of the drop the cat
is not rotating
halfway through the drop the cat is rotating
and at the very end Gi-Gi somehow stopped rotating
Newton’s first law says an object at rest will stay at rest
unless acted on by an external force
I see no external forces on this cat
So what’s happening here?
It’s not making sense to me
O.K. so in order to really get the right data
we’re going to have to drop her 90 degrees out of phase.
Got it girl
This time watch her tail
Okay so you think you figured it out.
Check this out you probably noticed that
when the cat was falling her tail was rotating in the direction opposite of where her body was rotating.
What’s interesting about that is that that’s not how it works.
In fact, even bobtail cats can do this.
It’s called the cat righting reflex.
I’ll prove it to you I came across some video from the 60s
when the Air Force was researching microgravity for future astronauts
turns out they took some cats up on parabolic flights.
猫会试图旋转它的尾巴 将自己翻过来 但失败了
He tries to rotate his tail to flip over but it doesn’t work he just ends up new tating wildly.
Then he does something interesting.
它拱起它的后背 当后背弯曲的时候 一些有趣的行为发生了
he takes his back and he bends it and when he bends his back and then creates motion something interesting happens.
Ah now we’re getting somewhere.
So let me show you one more cat flip with the mirror and we’ll figure this out.
Okay the arch back ends up being pretty important.
What he does is he divides his body up into two separate rotational axis that are tilted from one another
when he’s released he pulls his front paws in and does the ice skater trick
he decreases his moment of inertia in the front so he can spin fast up there.
But in the back he pushes his legs away from him increasing his moment of inertia.
So a really large twist in the front equals a really small twist in the back in the opposite direction
and the torques equal out.
So as soon as he gets his front paws in under him all he has to do is extend those legs back out to increase
that moment of inertia and stop the front twist
and extend his back legs along that rear axis that
allows him to twist those around really fast and then only has to do is pull them back in under his body
and then extend all four legs and brace for impact.
So thank you for your attention I hope you learned something pretty cool about cats.
You don’t mind oh okay.
Okay okay I’m done I’m done.
如果可以的话 我抓住吉吉后 可以带你看看其他与猫相关视频
If you would, go check out your other cat videos after trying to catch Gigi.
假如你喜欢的话 请点击吉吉 订阅频道 我们会感谢你的
If you’d like to click Gigi the cat to subscribe we’d appreciate it.
I hope you had a good one and with the ball.
看 多酷的猫 她让我们实验了很多次
Look. Very cool cat. She lets us drop her hundreds of times,
or you know maybe just five punch ball. Go get it.
Clicker if you want to subscribe oh but right now we’re playing bitch right.
嘿 这里是丹斯汀的Smarter Every Day 祝你开心
Destin here with Get Smarter Every Day. Have a good one.
One you earned it.
让我解释一下猫身体的奇特之处 首先 它们所有的身体部位都是为自己服务
Let me explain what cats are Wizards of physics first of all they have Physiology working for
them they have no working clavicle like I do and secondly they have very flexible back bones.
The talent needs a break.
Thirty centimeters or higher anything below that is unsafe not that we condone dropping cats here.
Hey go get in the catapult.
3 2 1哦伙计
Three two one oh man.