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科学美国人60秒 SSS 物理学帮你稳住拉杆箱

时间:2017-07-06 09:19:35

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(单词翻译)

Keep Rolling Luggage Upright With Physics 物理学帮你稳住拉杆箱

If you've ever pulled a rolling suitcase through the airport, chances are you've also been annoyed by this common occurrence: the suitcase starts rocking back and forth1 on each wheel and finally tips over.

如果你也曾在机场拉过滚轮行李箱,那你很有可能也被这种常见的情况惹恼过:行李箱的轮子开始不停地来回摇晃,最后翻倒了。

"It's a very classic phenomenon in physics." Sylvain Courrech du Pont, a physicist2 at the University of Paris Diderot. "So if you perturb3 the system it goes very easily unstable4. This is shared by many, many phenomena5 in nature."

“这是一个非常经典的物理现象。”来自巴黎狄德罗大学的物理学家,Sylvain Courrech du Pont说道。“所以如果你扰乱了这个系统,它就会很容易不稳定。这是许多自然现象所共有的特点。”

\Courrech du Pont and his students wanted to get to the bottom of why luggage tips. So they built what looks like the skeleton of a wheeled suitcase, and then filmed it rolling on a treadmill6. Then they modeled what they saw mathematically.

Courrech du Pont和他的学生想要弄清行李箱翻倒的真相。因此,他们建造了一个滚轮行李箱的骨架(看起来很像),然后拍摄它在跑步机上滚动。然后他们运用数学方式模拟了所见现象。

And here's what they found. Under normal rolling conditions, the forward motion of the suitcase is perpendicular7 to the wheels' axis8 of rotation9. All good. But when you hit a bump, or jerk the handle, one wheel lifts up. All of a sudden the pulling motion is no longer perpendicular to the still-rolling wheel's rotation, and the wheel corrects that by drifting towards the center. But by that time the other wheel's coming down, same thing happens, and now the suitcase is really rocking.

他们发现,在正常的滚动条件下,手提箱的前进运动垂直于车轮的转动轴。一切看起来都很好。但是当你撞到一个凸起,或者猛拉手柄,某个轮子就会被抬起。突然间,拉力运动不再垂直于仍在转动的滚轮的转动轴。而车轮通过向中心漂移来进行修正。但此时,那个轮子落到地面,同样的事情又发生了,因而箱子便厉害地晃动。

"And the first reaction you will have maybe is to slow down. But actually if you slow down you'll experience very big rocking oscillations." The way back to a smooth ride, he says, is to keep up your speed, or move even faster, once rocking begins. The study is in the Proceedings10 of the Royal Society A.

“你的第一反应可能是减速。但如果你慢下来,就会经历非常大的震荡。”他说,回到平稳行驶状态的方法,就是保持你的行走速度不变,或者一旦开始摇晃,就加快速度。这项研究发表在《英国皇家学会学报》A辑上。

There are other solutions to suitcase instability—like doing a better packing job. "If you put heavy stuff close to the axis of symmetry, or close to the wheel axis, then it's stable too."

解决滚轮不稳还有其他的办法,比如做好打包工作。“如果你把重物放在接近对称轴线上,或者靠近车轮轴线的地方,那么它也会很稳定。”

And Courrech du Pont has one more piece of advice to avoid rocking in the first place: "If you go slow enough it will always be stable." Keep that in mind, next time you're running to your gate.

Courrech du Pont还有一个可以从一开始就避免晃动出现的建议:“如果你走得够慢,那它就会一直平稳。”下次你急匆匆奔向登机口时,不防记住这一点。


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点击收听单词发音收听单词发音  

1 forth Hzdz2     
adv.向前;向外,往外
参考例句:
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
2 physicist oNqx4     
n.物理学家,研究物理学的人
参考例句:
  • He is a physicist of the first rank.他是一流的物理学家。
  • The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
3 perturb z3fzG     
v.使不安,烦扰,扰乱,使紊乱
参考例句:
  • Stellar passings can perturb the orbits of comets.行星的运行会使彗星的轨道发生扰动。
  • They perturb good social order with their lie and propaganda.他们以谎言和宣传扰乱良好的社会秩序。
4 unstable Ijgwa     
adj.不稳定的,易变的
参考例句:
  • This bookcase is too unstable to hold so many books.这书橱很不结实,装不了这么多书。
  • The patient's condition was unstable.那患者的病情不稳定。
5 phenomena 8N9xp     
n.现象
参考例句:
  • Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
  • The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系,如果存在着任何联系的话。
6 treadmill 1pOyz     
n.踏车;单调的工作
参考例句:
  • The treadmill has a heart rate monitor.跑步机上有个脉搏监视器。
  • Drugs remove man from the treadmill of routine.药物可以使人摆脱日常单调的工作带来的疲劳。
7 perpendicular GApy0     
adj.垂直的,直立的;n.垂直线,垂直的位置
参考例句:
  • The two lines of bones are set perpendicular to one another.这两排骨头相互垂直。
  • The wall is out of the perpendicular.这墙有些倾斜。
8 axis sdXyz     
n.轴,轴线,中心线;坐标轴,基准线
参考例句:
  • The earth's axis is the line between the North and South Poles.地轴是南北极之间的线。
  • The axis of a circle is its diameter.圆的轴线是其直径。
9 rotation LXmxE     
n.旋转;循环,轮流
参考例句:
  • Crop rotation helps prevent soil erosion.农作物轮作有助于防止水土流失。
  • The workers in this workshop do day and night shifts in weekly rotation.这个车间的工人上白班和上夜班每周轮换一次。
10 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼

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