滑冰中的物理现象(含慢动作) 视屏 文档 科普

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滑冰中的物理现象(含慢动作)

COLD HARD SCIENCE.The Physics of Skating on Ice (With SlowMo) - Smarter Every Day 110

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嗨 大家好 我是Destin 欢迎回到《每天更聪明》
Hey is me Destin. welcome back to smarter every day.
在奥运会中
So in the Olympics,
通常体格最健壮的队伍能赢得比赛 对不对
the most athletic team always wins right?
不是的 获胜其实比想象中更复杂
No. It’s actually more complicated than that
因为在奥运会中无生命的物体也发挥着作用
Beacuse there’s physical objects in the olympics.
能更好操控这些物体的队伍 通常比其他队伍更容易赢得比赛
Now the team that is able to manipulate these physical objects better than the other team usually wins.
比如说 冰壶
For example, curling.
这些冰壶非常的沉重
This curling stone is very heavy,
如果你能比其他队伍更好地操纵冰壶划过冰面
and if you can figure out how to manipulate it across the ice better than the other team
你就会获胜
you will win.
所以说物理学是一门大学问
So physics is a huge deal
而且掌握物理学知识非常必要
and a knowledge of physics is very important.
所以在今天的《每天更聪明》中
So today on Smarter Every Day
我们将会拍一个关于奥运会中使用的装备
we’re gonna start a three part series on equipment used in the olympics
以及这些装备的交互原理内容的三集系列片
and how it interacts with the world around it.
今天我们主要讲述滑冰鞋
Today we’re gonna focus on ice skates.
在奥运会中使用的冰鞋主要有三种类型
There are three major types of ice skates used in the olympics.
花样滑冰鞋
The figure skate,
冰球鞋
the hockey skate
和速滑冰鞋
and the speed skate.
这是我的新朋友Glenn
This is my new friend Glenn.
他是一名花样滑冰教练
He’s a figure skating coach.
他非常的帅气
It’s really awesome.
所以大家都已经知道了角动量的技巧对吧
So everyone already knows that angular momentum trick right?
大惯性转动 收腿
So large moment of intertia, bringing it in.
小惯性转动
Small moment of intertia.
这真棒啊
That’s pretty awesome.
给我看一下你的冰鞋
So show me your skates.
你是怎么做到的?
What makes you be able to do that?
因为如果换作是我的话 我会因为刀尖而搞砸的
Cause I mean, I would mess up because of the toe pick,
所以你到底是怎么转的?
so where are you actually rotating?
我其实在倒着转
I’m actually spinning backwards.
我的冰刀在倒着转
My blade is spinning backwards,
而我用一块很小的地方旋转 我们把这里叫做脚掌球
and I’m spinning on a small area we called the ball of the foot.
并且我的刀尖有碰到冰
Also my bottom topic is touching the ice.
它使我可以把重心放在前面
So it’s allowing me to put forward pressure down
而不会让我像站在冰球鞋上那样会往前滑
without sliding forward like I would on a hockey skate.
所以这就是你不往后倒的方法
So that’s how you’re able to keep from falling backwards?
是的
Right.
但我还是不太明白
Yeah I’m not really getting it.
他说他在大约这个位置转
He’s saying he’s rotating about this point
但是他在刀尖用力
but he’s dragging that toe pick.
他果然在蒙我
Clearly this is a good excuse to break out the Phantom.
好吧
Alright.
现在它合理了
OK now this is making sense.
我原来以为他们是以脚掌球上的某一个点来旋转的
You see I used to think that they pivoted on one spot under the ball of the foot.
看起来我是错的
Looks like I was wrong.
他们其实在倒着滑
They’re actually skating backwards
他拖着他的刀尖来保持平衡
and he’s dragging that toe pick to maintain his balance.
这真的很酷
That’s pretty cool.
好了 是时候来说一说跳跃了
Alright, it’s time to move onto jumps.
Glenn将会向我们展示花样滑冰中的三种主要跳法
OK Glenn’s gonna show us three of the main jumps in figure skating.
这是一个华尔兹跳
Here’s the waltz jump,
萨霍夫跳
the salchow,
和菲利普跳
and the flip.
在你起跳的地方你会留下一个沟槽
There’s a gouge where you left the ice,
是我利用刀尖起跳留下的
I pushed off my toe pick.
用刀尖起跳 这又有一个沟槽
Pushed off the toe pick, and then there’s another gouge..
然后我用刀尖着陆
And I landed on my toe pick.
然后往下落到我的冰刀上
But then I go down to my blade.
因此我推开了冰面
So I’m pushing off the ice with the toe pick,
伴随着刀尖的落地
with the toe pick.
我的刀尖先落地
with my toe hitting first
最后是我的冰刀刃落到冰面上
and then my blade.
Glenn将会做一个跳的动作
OK Glenn’s gonna do a jump
他将会通过他的刀尖着陆 就像他们每次做的那样
and he’s gonna land with his toe pick, which is how they always land.
这会增加他的稳定性
It adds stability.
你只有在落冰的时候 才能清楚的看懂花样滑冰鞋的作用
It’s in the landing of these jumps where the design of the figure skates really start to show.
你可以用刀尖把自己扎到冰里
You can spike yourself down into the ice with the toe pick
然后慢慢地把刀压下来
and then you slowly rock the blade down.
实际上冰刀底部的弯曲叫“摇杆”
In fact the curvature of the bottom of the blade is called the rocker.
当它稳稳的砸在冰面的时候
After it’s planted firmly on the ground
你会发现它没有马上移开
you’ll notice it doesn’t immediately move away.
滑冰者将另一条腿的动量转到他着地的脚上 然后他才开始移动
The skater imparts the momentum from his opposite leg back into his lower foot and then he moves.
所以这是由三个步骤组成的
So it’s a three step process.
刀尖落到冰面
Spike,
保持稳定
plant,
最后移动
move.
非常有趣
Interesting.
但我有一个问题 那就是
But a question I have is that,
如果冰刀是弯曲的 你怎么使圆形的冰刀变得锋利
if the bottom is rounded, how do you sharpen a round blade?
看起来这是一个把话题从花样滑冰鞋转移到冰球鞋上的好机会
So this seems like a good opportunity to move from the figure skate to the hockey skate.
让我们来见一下我的朋友尼克 他是一名UAH的冰球指导
So let’s meet my friend Nick who’s the director of hockey operations at UAH.
[冰球棍倒下] 所以你想向我展示
[hockey sticks fall over] So you want to show me..
不好意思
I’m sorry.
第二次了
Second time.
不好意思兄弟 让我看一下冰刀
Sorry dude, show me the blade,
它是怎么工作的
how’s this work.
你看 冰刀的这里
So the blades here, if you look,
分别有两个边 让我来给你画一下
it’s two separate edges so I’ll draw it up here for you.
好的
OK.
冰刀实际上是
Blade actually..
所以这是冰刀的横截面
So this is a cross-section.
看起来是这样子的
Looks like that.
不可能
No way!
很多人觉得它看起来是这样的 但其实它的中间是凹下去的
A lot of people think it looks like that but it’s actually, there’s a hollow in here.
真的
Really.
是的
Yep.
– 我们可以看一下磨刀器吗?- 好的
– Can we see the sharpener?- Yeah.
我喜欢这个名字
I like the name
冰刀之王
Blademaster!
这是砂轮 用来磨冰刀的
This is the wheel, which actually sharpens the skate.
你怎么固定住冰刀
How do you hold the blade up there?
这是一个滑杆还是什么
Is this a sled or something?
夹具 滑杆 每个人都有不同的叫法
Jig, slider, everybody’s got their own little nickname for it.
所以在砂轮转动时 你会把冰刀放到这里
OK and so then if the wheel were turning, you would bring that in there
让我集中注意力
let me focus.
好的 我能看出你说的凹陷
OK I can see that curvature that you’re talking about.
你能更近一些吗 如果你能转动它
Can you go closer if you would to the wheel.
所以那是冰鞋的半径 3/8 1/2 和5/8
So that’s the radius of the skate, 3/8ths, half, 5/8ths.
我不确定我明白
I’m not sure I understand.
你说这里的这个凹槽
You’re saying this hollow right here..
是的 它们一部分是这样的
Yeah some of them will look like that,
其他的是这样的 还有些是这样的
some of them will look like that, some of them will look like that.
这个真是让我大开眼界
This is completely eye opening to me.
我原来完全不知道冰刀有两个分开的刃
I had no idea that ice skates had two different working edges.
所以为什么选手会喜欢深凹陷 而不喜欢浅的呢
So why would a player prefer a deeper hollow vs a shallower one?
想象一下
Well think about it.
如果你有一个浅的凹陷 你可以在冰面上
If you have a shallow hollow you’re able to sit on top of the ice
滑翔地很轻松 这对快速移动很有帮助
and glide very easily so this is very good for speed.
但是如果你有一个深的凹陷
But if you have a deep hollow,
你的刀刃会嵌到冰里所以你会减速
your points are gonna cut down into the ice and plow so you’ll go a lot slower.
可是你的抓地力会增强
However you’ll get much better grip.
冰球运动员最需要的就是抓地力
And if there’s one thing a hockey player needs it’s good grip.
你有见过他们快速转向吗?
Have you ever seen them stop and change directions?
因此我让几名冰球运动员为我演示 冰刀的两个刃在急停中的作用
So I’ve asked a couple of hockey players to show me how this double edge is used to stop on ice.
看呀 物理学是多么棒啊
Behold, the awesomeness of physics!
这不疯狂吗
Isn’t that crazy?
看他在干什么
Look at what he’s doing.
他控制着那一个刃
He’s controlling that edge
并刮掉了一层冰
and scratching the top layer of ice off,
他把横切的力转化成使他减速的摩擦力
but he’s doing it in such a way that it’s converting that shear energy into power which he’s using to decelerate.
有些人认为冰球运动员都有点蠢
Some people want to believe that hockey players are just dumb brutes,
但是我并不赞同
but I’m not buying it.
我告诉这名运动员我想让他在冰上特定的点停住
I told this player I wanted him to stop on a very specific spot on the ice.
这样我就可以捕捉到运动轨迹并录到冰喷洒起来
so I could zoom in with the phantom and catch the ice spray,
他一次就做到了
and he did it on the very first try.
你能想象到他脑子里经过了怎样的数学计算才使它自动做出这一条件反射般的运动
Can you imagine the math that’s going on in his brain in order to automate this feedback loop?
他总是能感知到自己的减速
He’s constantly sensing his deceleration
他的大脑使这些信息转变成控制冰刀角度的信号
and somehow his brain’s converting that information to signals
和控制他磨掉的冰的数量
to control the angle of his skates invented the exact amount of ice that he’s shearing off.
最难的是
To complicate matters,
他与他的目标之间隔绝着冰
he’s got ice in between him and his target
他需要预测留在冰面的推动力的大小
and he has to anticipate the total amount of impulse left in that ice
这样他才可以准确地停在自己想停的地方
so he can stop exactly where he wants to.
让我们来问一下他看他能否准确解释出自己到底在做什么
Let’s ask him to see if he can explain exactly what he’s doing.
因为我很确信冰球运动员都是物理天才
Because I’m pretty sure hockey players are physics geniuses.
你不需要摘掉你的手套
You don’t gotta take your glove off man
Ben 非常感谢
Ben, thank you very much.
你有没有什么需要说的 比如关于冰球急刹
Do you have any, like if you had to say anything about that hockey stop,
你到底是怎么具体做到的?
how exactly do you do it?
你首先需要找到平衡
Well you’re just trying to find a balance,
因为你的冰刀上有两个刃
because you have two, there’s two edges on the skate blade,
所以你会想找到内刃
so you wanna find that inside edge,
你知道如果你踩到外刃上你会摔倒
you know if you get over the top of your outside edge you go over.
所以你想找到那个只会磨掉一层薄冰的刃
So you’re trying to find that edge on the ice and just shave a fine mist.
那就只有内刃能做到
Just the inside one.
所以像刚开始学的新手
So like a noob, somebody that’s just learning how to do that,
他们是不是只会一路发出吱吱的声音呢
would they just chatter across the ice?
是的 当我刚开始打冰球的时候我大概只有三岁
Yeah. When I started playing I was like three years old so,
– 好像在我六岁的时候我才学会急刹- 是的
– maybe by the time I was like six I could stop. – Yeah.
大约几年 但是……
So a couple of years, but like..
你刚才是不是并没有看着冰球就击中了它
Did you just hit that puck without looking?
– 是的- 他刚才把冰球打过来 你在没看的情况下击中了冰球
– Yeah. – He just hit a puck and you hit it without looking.
我的意思是我看见了
I mean I saw it.
好的 我是对的 他们是天才
Yep I’m right, they’re geniuses.
所以我们希望冰球刀能抓住冰面 但不希望速滑刀这样 对吗?
So if we want grip for a hockey blade we don’t want it for a speed skate, right?
这也许可以解释为什么速滑运动员经常摔倒
Which might explain why speed skaters are always falling.
对我来说这是违反直觉的 但是速滑鞋的底不是尖的
This was counterintuitive to me, but the bottom of a speed skate isn’t pointy.
它实际上是一个平直的90度角
It’s actually a flat sharp 90 degree angle.
让我们去到密尔沃基的国家滑冰中心去看一看速滑运动员滑冰
To see speed skaters in action let’s go to the Pettit National Ice Center in Milwaukee
并去看一看美国青少年长道速滑的比赛吧
and check out the US junior long track championships.
看看滑冰者们怎么起滑的
OK look at how the skater starts off the line.
你看到他们伸展的姿势了吗?
You see that open stance?
他们这样做是因为冰鞋的摩擦力是不均匀的
They do this because ice skate friction is asymmetrical.
他们可以很容易地往前滑 但是往两边滑的摩擦力却很大
They glide easily going forward but they dig in on the sides.
所以为了推动他们自己前进 滑冰者们需要推动冰刀的边缘
So to propel themselves skaters have to push off the sides of the blade.
这个角度越大 他们推得就越难
The larger this angle alpha is, the harder they can push.
这就是为什么他们在起滑时 将冰刀对着他们要滑行的方向呈90度的原因
That’s why they line up with their foot at almost a 90 degree angle to the direction of skating.
速滑刀都是平的
Speed skates are flat
这就代表了他们的每一步都要在落冰的时候呈现完美的水平角度
which means each individual stride has to be perfectly level when the foot hits the ice.
这就会成为一个问题
This can be a problem,
因为踝关节向下用力的时候 冰刀会翘出冰面
because when you extend your ankle the blade tries to come up off the ice.
而解决方案就是克莱普冰刀
The solution to this is called a clap skate.
克莱普冰刀使长道速滑运动员更好的保持他们的冰刀在冰面上
Clap skates allow a long track skater to keep their blade on the ice longer into the stride.
我会让Adam来解释一下
I’ll let Adam explain.
克莱普冰刀一开始是出来的 像这样
The clap starts to come out, like this,
当他们抬起冰鞋时 冰刀就会收回 像这样
and once they pick their skate up it just kinda just flies back like that.
所以这个多余的推动使克莱普冰刀给你更多与冰面接触的时间
And so that extra push that makes the clap, gives you a lot more contact on the ice.
因此你可以获得更多的力量
And so you can get a lot more power.
在说这么多关于滑冰的事之后
All this talk about ice skating
我们从来没有解释过为什么冰面总是很滑
and we didn’t even explain why it’s slippery in the first place.
有一种东西叫摩擦融化
So there’s this thing called friction melting.
如果你把某样物品从冰上滑过的时候
If you’re moving something along ice
会产生一层水的薄膜 大约一微毫米厚
it creates this really thin layer of water, think like nanometers thick.
这就是为什么你可以在冰面上轻松滑行的原因
That is why you can slip on ice so easily.
它的摩擦系数可以用这个公式来解释
The coefficient of friction can be defined by this equation.
这真的非常有趣
It’s very interesting.
好了 这可能还有几个你可能感兴趣的事
OK, a couple more things you might be interested in.
第一
Number one,
我们正在做关于这些冬季运动的信息图
we’ve been making infographics of all these winter sports.
你可以把它们下载下来并分享给你愿意分享的人
You can go download those and share them with whoever you like.
另外我想感谢让我做这些疯狂的事情的赞助商
Also I’d like to thank the sponsor that lets me do crazy things
比如说 尝试着向我解释我并不是很明白的运动
like try to explain sports I don’t really understand.
那就是audible.com
So that’s audible.com.
你可以通过进入网站audible.com/smarter来支持《每天更聪明》
You can support Smarter Every Day by going to audible.com/smarter
你可以免费获得一本任何你想要的电子书 他们有上千本电子书呢
you get a free audio book, whatever you want, they’ve got thousands of titles.
我在他们成为《每天更聪明》的赞助商之前 就在用audible
I used audible before they asked to be a sponsor for Smarter Every Day.
所以我非常乐意把它推荐给你们
So I’m more than happy to suggest that to you.
audible.com/smarter
audible.com/smarter
《每天更聪明》将通过audible得到分红
Smarter Every Day will get credit,
这可以帮助我们更好的进步 做更多像这样疯狂的事
and that’ll help us move forward, do more crazy stuff like this.
说更多像这样疯狂的事
Speaking of more crazy stuff like this.
如果你想看更多关于冬奥会的视频
If you would like to see more videos on winter olympic sports,
后续几条视频 我会试着尽快推出
the next couple of videos, I’m gonna try to get them out pretty quick,
后续视频将会有冰壶以及更多像这样的内容
are things like curling, and other stuff like that.
这真的很酷
It’s pretty cool.
总之 请支持我们的赞助商 audible. com/smarter
are things like curling, and other stuff like that.
如果你觉得我们已经在你订阅的考虑范围以内 那就请关注我们把
and if you think we’ve earned your subscription consider that please.
我是Destin
I’m Destin,
你每天都在变得越发聪明
you’re getting Smarter Every Day.
非常感谢您的收看 祝您有美好的一天
Thanks for listening to me I appreciate that. Have a good one.
为什么你总是伸展你的手
Why are you putting your hands out all the time?
为什么我经常看见花样滑冰运动员这么做
Why do I always see figure skaters do that?
因为我的教练一遍一遍的告诉我要这样
Because my coach told me to, over and over.
这样可以帮助我保持平衡
It helps with my balance.
用我的双臂
Using my arms to rotate,
来转动我自己
turn myself.
必须有点戏剧性
And to be a little more dramatic.
你需要一些技巧来完成它 对吗
You gotta have a little finesse to it right?
这真棒
That’s awesome.
字幕 Andrew Jacksoncaptionsbyandrew. wordpress.com
[ Captions by Andrew Jackson ] captionsbyandrew.wordpress.com
欢迎将它翻译成不同的语言如需帮助请联系Destin
Captioning in different languages welcome. Please contact Destin if you can help.


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