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有争议的冰壶物理现象

COLD HARD SCIENCE. The Controversial Physics of Curling - Smarter Every Day 111

嘿 又是我 Destin
Hey it’s me Destin,
欢迎回到“聪明日”
welcome back to Smarter Every Day.
在上一集中我解释了
So in the last episode I explained
体育运动中并非总是最强有力的球队获胜
that it’s not always the most athletic team that wins in sport,
有时 获胜需要灵活控制物体的能力
sometimes it involves the physical manipulation of objects,
所以 胜利也属于最聪明的队伍
so sometimes it’s the most intelligent team.
在今天的“聪明日”里
So today, on Smarter Every Day,
让我们来探讨冰壶运动中的
let’s take a look at the physics
物理学吧
of curling.
[音乐]
[music]
在观看球员打球之前
OK. Before we watch some curlers,
我们要先了解这项运动的基本知识
we need to learn the basics of the sport.
这是冰壶赛道 圆圈是圆垒
This is the curling sheet and the circles are the house.
冰壶离圆心越近的队伍即可得分
The goal is to get your team’s rock closest to the button.
每队有4名队员
There’s four people on each team.
投手
The thrower,
两名刷冰员
the sweepers,
和负责指挥投球的队长
and the skip who’s in charge.
每个队投八次冰壶
Each team has eight stones to throw,
每名队员各投两次
so each person throws two.
两队轮流投掷
They alternate with the other team
因此每局总共投掷16个冰壶
so there’s a total of 16 stones thrown.
后投壶的队伍叫做后手
The very last one is called the hammer,
会有很大的优势
which is a major advantage.
你们能想象在阿拉巴马州找到冰壶有多难吗?
Do you have any idea how difficult it was to find a curling stone in Alabama?
真的非常难
It is really hard.
不管怎样 我知道你在想什么
Anyway, so I know what you’re thinking,
冰壶运动就像穴居野人的运动 对吗?
curling is like cave man sport, right?
我要在冰上滑动这石头 然后再撞击另一块石头
I’m gonna slide this rock on ice and I’m gonna hit another rock
把对方的石头击出场
and we’re just gonna try to out-rock each other.
但是 冰壶远不止这点难度
But oh no,
它比这要难的多
it’s way more difficult than that.
事实上在我仔细研究冰壶如何运动之前
In fact,
有许多我从未考虑过的事情
there’s so many things I had never even considered
直到我近距离观察它到底如何运转的
until I took a closer look at how this works.
例如 其中最简单的问题
For example, the simplest question of them all,
为什么冰壶会作曲线运动?
what makes a curling stone curl?
让我们假设一下这不是咖啡桌
OK let’s pretend for just a second
而是一个冰壶赛道
that this isn’t my coffee table,
它表面确实是一个曲面
it’s actually a curling sheet.
我们在观看比赛的时候得知
So we know from watching TV
一名队员回到后方
that when a player is back here at the hack,
也就是发球区
which is where they start,
并把冰壶推向你所在的冰上的圆垒
and he pushes it toward the house where you’re at,
这个圆垒就是冰面上的圆心
which is the bullseye on the ice,
当队员使冰壶逆时针自转时
as he rotates it or spins it counter clockwise
它会按着自转的方向旋转 对吗
it’ll curl in the direction of that rotation, right?
现在 我假设这与此有关
Now my assumption is that has something to do with this,
这叫移动环
which is called the running band.
我们可以看到冰壶的底部是凹的
You’ll see the bottom of the curling stone is concave,
但是有一个圆形的摩擦面
but there’s this circular frictional interface
与冰面接触
that interfaces with the ice.
所以我们能模拟一个在坚硬表面上
So we should be able to model a circular frictional interface
滑动的物体形成的圆形摩擦界面 对吧
of a moving sliding object on a rigid surface right?
这里
Which is this,
我拿了一个玻璃杯
a glass.
我要用这个圆形物体
I’m gonna take this circular object,
倒放到这个摩擦力低的表面上
I’m gonna put it down on the low friction surface,
然后将它推向你并使它快速旋转
I’m gonna push it towards you and spin it,
然后期待它在旋转方向上作曲线运动
and expect a curl in the direction of rotation.
让我们试一试
Let’s give it a shot.
但我没看到 让我们再试一次
But I don’t see that. Let’s try this again.
放下杯子推向你 旋转出曲线
Set this down, push toward you, spin it, curl.
我们来看看
Here we go.
不 它向相反的方向旋转
No. It curls in the opposite direction.
这实际上 让科学家困惑了很长时间
This is actually what’s really confused scientists for a really long time.
在坚硬表面上作正常滑动旋转的物体的接触面
That interface of a normal moving sliding spinning object on a rigid surface,
运动轨迹完全不同于
behaves completely different with normal objects
冰壶石的接触面做出的运动轨迹
that it does with a curling stone.
这是因为冰壶上的移动环
There’s something magical happening right here on this running band
在冰壶石和冰面的摩擦下发生了神奇的变化
between the stone and ice.
所以很明显 下一步我们要找一些冰
So clearly the next step is to go find us some ice.
噢!
Ohhh!
我把我裤子弄湿了 让我们再试一次
I wet my pants. Let’s try again.
天啊 所以冰壶是朝着自转的方向运动
Oh man. So the curling stone goes in the direction of rotation
但杯子却相反 我能理解 因为
but the cup goes opposite, which I can understand because
当它在桌子上减速时 它试图倾斜
as it’s decelerating on the table. it’s trying to tip over,
给杯子的前缘造成更多的力
causing more force on that leading edge of the cup.
所以当它快速旋转的时候
So when it’s spinning,
它的前缘会对桌子产生推动力
it’s pushing against the table with its leading edge.
这对我来说很容易理解
That makes sense to me.
那我们去威斯康辛州的密尔沃基冰壶俱乐部吧
So let’s go to the curling club in Milwaukee Wisconson.
看看他们是否能用现成的冰场地教我们一些东西
and see if they can teach us something with prepared ice
最重要的是 技能
and skill, most importantly.
我们在密尔沃基冰壶俱乐部
We are at the Milwaukee Curling Club.
位于奥佐基县的集市上
We are located at the fairgrounds in Ozaukee County.
这个俱乐部是美国现存历史最悠久的冰壶俱乐部
This club is the oldest continuous curling club in the United States.
在比赛开始前 冰一定要准备好
(Destin) Before a game can be played the ice has to be properly prepared,
这本身就是一门技术
which is a science within itself.
如果把冰壶放在平坦的冰面上
If a stone rests on flat ice,
它会产生大量的接触摩擦
it creates a lot of contact friction
使冰壶滑行缓慢重力作用于平坦的表面
which makes the stones run slowly.
制冰师使用一种叫做“冰粒”的复杂技术
Curlers use an intricate technique called pebbling
以减少冰壶在冰面上的摩擦
to decrease the friction of the stones on the ice.
去离子水 经过逆向渗透净化
Deionized water that’s been purified by reverse osmosis
再以一种特殊的方式被洒在冰面上并结冰
is sprinkled onto the ice in a very specific way and allowed to freeze.
你可以看到Jay来回挥舞着喷头洒水以制造冰粒
Here you can see Jay pebbling the ice by swinging a sprinkler nozzle back and forth.
你无法想象在此过程中需要控制的变量
You can’t imagine the amount of variables that have to be controlled during this process.
手臂摆动的次数 他走路的速度 湿度
Number of arm swings, how fast he walks, humidity,
水箱和喷头的高度差
the difference in height between the tank and the sprinkler head,
水的温度
the temperature of the water.
是的 这让人难以置信
Yeah,it’s pretty crazy.
他们用扫冰机将冰粒的顶端打磨掉
After pebbling they use a blade to nip the top of the pebbles off
来做出平滑均匀的滑行面
to create a smooth uniform running surface.
因为冰粒顶端受到的压力更大
Because there’s more pressure on the tops of the pebbles,
所以有更多的摩擦粒融化减少了摩擦
there’s more friction melting which causes less friction.
也因此我们需要刷冰 在我研究冰壶之前
Which leads us to sweeping. Before I researched curling
我还以为是刷冰员以某种方式
I thought the sweepers were somehow
增加或减少了石头的一面
increasing or decreasing the friction on one side of the stone
或另一面的摩擦力来使其旋转
or the other and making it curl.
其实我完全错了 刷冰员刷冰是为了加热冰面
I was absolutely wrong. The sweepers actually sweep in order to heat
让冰壶旋转得更少 如果你扔两个完全一样的冰壶
the ice up and make it curl less. If you threw two stones exactly the same
一个刷了冰 一个没刷 你会发现刷过的冰壶
and you didn’t sweep one but you swept the other, you would find that the swept one
会滑得更直 更远
would go straighter and farther.
这是冰上冰粒的一个扫描电子显微镜图像
This is a scanning electron microscope image of a pebble on the ice.
你可以看到顶端凸起在冰面上 因此它是刚做好的
You can see that it’s been nipped on the top, so it’s fresh.
然而 这是一个冰粒被刷过之后的图像 你可以看到
This however is an image of a pebble after it’s been swept. You can plainly
当它被刷子刷过 融化处会有明显的粒状纹理
see that there’s grain boundaries from where it melted when it was swept with a broom.
那薄薄的一层水形成了润滑层
That thin layer of water that forms acts as a lubrication barrier,
减少了摩擦 让石头移动得更快更远
reducing the friction and allowing the stone to travel farther and faster.
所以这就是有趣的地方
So this is where it gets interesting.
我们要弄明白为什么冰壶石会旋转 对吧?
So we’re trying to figure out why the curling stone curls right?
所以我找了一圈 找到了国际上研究冰壶物理学方面的专家
So I look around and I find the international experts for curling physics.
我在加拿大找到了他
I find the guy in Canada,
并且在瑞典找到了一个团队
and I find a team in Sweden.
因此我开始阅读他们所有的资料
And so I start reading all their papers.
结果这些人想法都十分地一致
Turns out these guys are not even close to agreeing.
这真的很有趣
It’s really interesting.
事实上 他们之间甚至从未说过话
In fact they’ve never even communicated with their voices.
他们只是通过技术文件进行交流 这真令人着迷
They only communicate via technical paper. Fascinating.
我给他们打了电话
I called the guys up on the phone
和双方团队聊了大概一个半小时
and I had like an hour and a half conversation with both groups,
我试着去理解真正的原理是什么
trying to understand what exactly is the mechanism.
瑞典乌普萨拉大学的Harald Nyberg
Harald Nyberg at Uppsala University in Sweden
向我解释了划痕理论
explained something to me called the scratch theory.
想象着一个冰壶自转并沿着冰面移动
visualize a stone rotating and moving down the ice
现在想想移动环
Now think about the running band
和那些划痕所形成的
and what the scratches that would make
看起来就像冰壶从床单上滑过
look like as it goes down the sheet.
随着它的下滑 移动环的边缘会
The edges of the running band would make this really awesome
相互重叠 这真是太妙了
overlapping pattern as it slides down.
瑞典科学家说
The Swedish scientists say
因为环后面粗糙的地方
that because the rough spots at the rear of the band
会跳过移动环前缘形成的划痕
have to hop over the scratches created by the leading edge of the running band,
这将使冰壶的后方产生一种使它自转的力
this will induce a force on the rear of the stone making it curl in the direction of rotation.
他们声称通过展示冰粒的图像可以证明这一点
They claim to prove this by showing images of pebbles
在某一角度 冰壶滑过它们之后 冰粒被刮出划痕
that have been scratched at an angle after the stone slides over them.
他们还做了一个实验
They also did an experiment
从两个角度分别用砂纸在冰面上深深地划过
by scratching ice really deeply with sandpaper at two angles
推动冰壶穿过划痕而不旋转它
and pushing a stone across the scratches without rotating it.
推动冰壶穿过划痕而不旋转它
and pushing a stone across the scratches without rotating it.
瑞典教授:现在用擦亮过的冰壶做同样的实验
(Swedish Professor)”And now the same experiment with the polished stone.”
瑞典教授:见证科学的时候到了
(Swedish Professor)”Here comes Harald.”
较年长的瑞典教授:是的!
Elder Swedish Professor: ” YES!”
相当有说服力 对吗? 没那么快
Pretty convincing right? Not so fast.
加拿大北不列颠哥伦比亚大学Mark Shegalski博士
Dr Mark Shegalski at the University of Northern British Columbia in Canada
曾经投掷了一个冰壶 这个冰壶有抛光了的金属移动环
once threw a stone with a polished metal running band
它不会产生那样的划痕
which doesn’t produce the same type of scratches.
在刚铺好冰粒的冰面上 他观察到
He observed that it curled like a normal stone
它的旋转跟扔普通石头一样
by throwing it on freshly pebbled ice.
Shegalski博士认为
Dr Shegalski believes that the mechanism is
这是非对称摩擦融化原理
something called asymmetric friction melting.
当冰壶在冰面上移动
When the stone travels over the ice,
摩擦生热使冰面融化
the friction heats up the ice and melts it,
产生了我们之前讨论过的润滑层
creating that lubrication barrier that we discussed earlier.
由于冰壶倾向于翻倒 他认为正面比背面有更多的湿润摩擦
He believes that there’s more frictional wetting on the front side than the back
就像在之前的实验中我们用杯子做出的一样
due to the rock tending to tip over, just like the cup did in our earlier experiment.
另一个可能的原因是因为冰壶
Another possibility is that because the side of the rock
相对于冰面往前移动的速度快于后退的速度
that’s advancing moves faster relative to the ice than the retreating side,
这会形成更多的润滑
it could be creating more lubrication.
如果你回顾接触差异部分的知识 你应该能设想出这点
You can visualize this by looking back at the difference in the contact patterns.
这额外的相对运动将会在顶部产生更多的摩擦生热
This additional relative motion would create more frictional heat up on top,
这将会融化更多的冰
which would melt more ice.
然后 这些水会通过冰壶的旋转被传送出去
This water could then be transported forward by the rotation
使移动环的前缘比后缘更润滑
and lubricate the leading edge of the band more than the rear edge.
冰壶的前倾或者是水传送理论
That forward tipping of the rock or the water transport theory
将推动冰壶朝着旋转方向移动
pushes the rock into the direction of rotation.
两位科学家都深信他们的理论是
Both scientists are convinced that their theory
发生在移动环后面的主要原理
is the dominant mechanism taking place at the back of the running band.
但是他们都认为还有更多的工作要做
But they agree however that more work still needs to be done.
我个人认为这两个理论中没有一个能全部解决冰壶运动的问题
Personally I don’t think either one of the theories can stand up to all of the questions on its own.
我认为终极形式可能是这两种理论的结合
I think the ultimate model might be a combination of both of the theories.
Shegelski博士认为 在这里起作用的可能还有一到两个其它的原理
Dr Shegelski believes there may even be 1 or 2 other mechanisms at play here
能描述神秘的冰壶运动 谁知道呢
that would help describe the mysterious motion of the curling stone. Who knows,
然而 我所知道的是 那些有科学家研究冰壶物理学的国家
what I do know however is that the nations that have scientists researching the physics of curling
通常也是有最多冰壶奥运选手的国家
are the same nations that most often have olympic athletes on the podiums for curling.
嘿 在我下班回家的路上 我有个重要的事要说
Hey I have a huge announcement here on my way home from work.
我不能确定你能看懂 但是这些视频花了很多时间和精力
I’m not sure if you can tell but these videos take a lot of time and effort.
是的 你行 你很聪明 你知道我在做什么
Yeah you can, you’re smart.You know what I’m doing here.
你知道两位冰壶专家的不同之处 对吧?
You know how there are two different experts for curling right?
我向他俩请教 以得到最好的观点
And I consulted them both to get the best idea.
我在其他事上也做了同样的事情
Well I’ve done the same thing for something else.
来自Patreon的Jack Conte和Subble的联合创始人Hank Green
Jack Conte from Patreon and Hank Green, co-founder of Subbable,
创立了两个不同的平台 像我这样的内容创作者
have created two different platforms that content creators like me
可以为他们所做的事情提供内容支持
can use to try to generate support for what they do.
如果你喜欢聪明日节目 或是有不错的点子想放到这个节目里
Now the idea is if you enjoy and place some kind of value on Smarter Every Day,
可以自愿加入进来 我不是开玩笑
that you can voluntarily… You can, I’m not saying do,
你可以自行决定如何协助我
but you can voluntarily decide to assist what I do.
不管怎样 你可以去这些页面中的任何一个 Patreon或Subable
Anyway, you can go to either one of these pages, Patreon or Subbable,
那里有各种各样的好处
and there’s all kinds of different perks on there.
有很多方法可以联系到我 有海报
there’s ways to reach out to me, there’s posters
有各种各样的东西 信息图
there’s all kinds of stuff Infographics.
所以Patreon 是单一视频类型
So Patreon is a per video model,
Subbable是单月视频类型 现在我不知道什么方法最好
and Subbable is a per month model. Now I didn’t know what would work best
所以我联系了这两人
so I contacted both these guys
决定亲自测试一下 看看哪一个更适合“聪明日”
and decided to test it for myself to see which one works the best for Smarter Every Day.
不管怎样 你可以测试它们 看看什么最适合你
Anyway, you can test them and see what works best for you.
无论如何 我将把链接留在“聪明日” Patreon和Subable页面
Anyway, I’ll leave links to the Patreon and Subbable Smarter Every Day pages
如果你愿意支持“聪明日”
and if you would be willing to support Smarter Every Day,
那就太棒了 它将使我的生活更好
that would be awesome. It would make my life better
因为我可以简化我的工作流程 并有可能成为一个更好的父亲
because I can streamline my workflow and probably be a better dad
因为我会有更多的时间
because I might have a little more time.
总之 我是Destin 就算你只是考虑一下 我也非常感谢
Anyway, I’m Destin. Thank you for even considering that.
Subbable和Patreon 聪明日
Subbable and Patreon, Smarter Every Day.
我会把链接留在这里和视频介绍中 谢谢 再见
I’ll leave links here and in the video description. Thanks, bye.
(笑声)
[laughing]
你在你的房子里做这个 对吗?
You’re trying this at your house right?
(玻璃打破声)噢
[Glass breaking] Oh
(悄声)完蛋 我把杯子打碎了
[whispered] crap. I just broke it.
别说出去
Don’t tell on me.
在物理学中有一个原理叫做动量守恒
In physics there’s a principle called the conservation of momentum,
如果动量是质量乘以速度 冰壶都有相同的质量
so if momentum is mass times velocity and the curling stones all have the same mass,
你可以假设它的速度是守恒的
you could assume that it’s velocity that’s conserved.
在撞击之前 石头的前进速度很大程度上
For the most part, the forward velocity of the stone just before impact
相当于冲击后整个系统的前进速度
is gonna be equivalent to the forward velocity in the system just after impact.
这在X轴和Y轴上都成立
This works for both the X direction and the Y direction.
因为在碰撞前没有横向速度
Since there’s no sideways velocity before impact,
撞击后的横向速度就等于零
the lateral velocity after the impacts has to equal out to zero.
这是不是很酷?
Isn’t that cool?
Andrew Jackson附注
[ Captions by Andrew Jackson ] captionsbyandrew.wordpress.com
欢迎译成不同语言的字幕 如果你愿意帮忙 请联系Destin
Captioning in different languages welcome. Please contact Destin if you can help.

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译制信息
视频概述

冰壶在冰面做曲线运动的奇特物理原理

听录译者

收集自网络

翻译译者

D.M.

审核员

审核员 GK

视频来源

https://www.youtube.com/watch?v=7CUojMQgDpM

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