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  • Balancing a pencil or any other tough, heavy object on its tip,

    要讓鉛筆或其他堅硬重物在尖端直立

  • is quite a precarious task.

    是很困難的 會搖搖欲墜

  • It is easy to see why tough heavy object are unstable.

    堅硬重物不易立起的原因很簡單

  • They justwanna fall down.

    它們就是會自然而然的倒下

  • Any little nudge, will put it off balance,

    只要輕輕一推 就會失去平衡

  • with gravity, happy to pull its center of mass even more off balance

    因為地心引力的關係 一失去重心就會倒下

  • And the more off balance, it is the more gravity pulls in too!

    重心越傾斜 地心引力的作用就越強烈

  • Physicist calls this kind of tipping an...Inverted Pendulum.

    物理學家稱這種現象為 倒單擺作用

  • Because its kind of, likean upside-down pendulum.

    因為這有點像上下顛倒的鐘擺

  • And careful mathematical analysis of Inverted Pendulums...will tell you the obvious,

    經過精密的數學分析 結果顯而易見

  • theyre reallyunstable.

    這真的…很不穩定

  • In fact, this equation predicts that

    事實上 藉由公式運算 能夠預測

  • if a perfectly balanced pencil with a perfectly-sharped tip,

    一隻有著完美筆尖的鉛筆 完美平衡後

  • will do get nudge, off balance, by just one ten thousandth of the width of an atom.

    只要輕輕一推 哪怕只偏離0.0001個原子量

  • It would take only three seconds, to fall over...

    只要三秒鐘 鉛筆就會完全倒下

  • There are indeed acrobats, who can balance poles, with other acrobats on top.

    有些雜技演員 能平衡上頭站了一人的長竿

  • And the robots, they can balance and, catch and throw, upright sticks!

    有種機器人能 平衡 甚至拋接 直立的竹籤

  • And the people who make... seemingly impossible, artistic, rock stacks.

    有人還能以不可思議的方式堆疊石頭

  • But in all these cases,

    但 在以上這些情況

  • keeping the objects balance, either requires an active stabilization effort,

    要維持平衡 除了利用動態平衡以外

  • Or else, carefully taking advantage of the fact that

    另一個方法是利用物理現象-

  • the balancing point...isn't actually...a point!

    所謂的平衡點 其實並不是一個點!

  • So, the question is this:

    問題來了

  • Can you balance a pencil sharpened to a perfect, single, atom-wide tip, on its tip?

    要怎麼用原子大小的尖端 立起一隻鉛筆?

  • Without active stabilization?

    而且不利用動態平衡?

  • Well, to start, you better get rid of the air bumping in besides the pencil.

    首先 要排除鉛筆四周流動的空氣粒子

  • Since the kinetic energy of a typical oxygen molecule,

    因為一個氧分子的動能

  • is enough to destabilize the pencil.

    就足夠使鉛筆失去平衡

  • Remember, if the pencil gets off center by even ten thousandth of the width of an atom,

    記住 就算鉛筆重心只偏移0.0001個原子量

  • it would fall down in, under three seconds.

    它就會在三秒後倒下

  • And you better cool the pencil and table down as close to absolute zero, as you can...

    另外 要盡量把鉛筆和桌子都冷卻到絕對零度

  • since the thermal jiggling of their atoms when they're hotter, are similarly jiggle the pencil off balance.

    因為熱能會使原子運動 溫度越高越難平衡

  • But even then, matter add very small scales has spread out wape like nature

    但即使如此 還是會有自然的微小波動

  • which means that you cannot have both pencil perfectly upright,

    也就是說 保持鉛筆完美平衡的同時

  • and not moving at the same time.

    無法維持鉛筆的絕對靜止

  • And while this "quantum effect" is never a real life inhibitor of the precarious pencil balancing?

    這種量子效應從不存在於鉛筆直立中

  • It means, you never even could succeed...

    所以 永遠無法成功立起鉛筆

  • However, it is still fun to see, how long you can keep a pencil balanced on your fingertip.

    但是 挑戰在指尖立起鉛筆 還是很好玩

  • The shorter the pencil, the harder it is.

    鉛筆越短就越困難

  • My best time for a standard nineteen centimeter pencil

    我平衡標準19公分鉛筆的最長時間是

  • was one point three seconds.

    1.3秒

  • Do you think you can beat that?

    你有辦法超過我嗎?

  • This minute physics video is brought to you by audible.com

    這部影片由audible.com贊助播出

  • one of the leading providers online, audio books, and all types of media,

    audible是線上有聲書與媒體的領導品牌

  • either fiction, non-fiction, and periodicals..

    產品包含小說 非小說 與期刊

  • I'd like to recommend "The Tipping Point" by Malcolm Gladwell this week.

    本周推薦Gladwell的The Tipping Point

  • It is a book about exponential increases and spreads of trends,

    這本書是關於流行趨勢的指數增加與傳播

  • social trends, academic, that sort of thing,

    像是社會風潮 學術 等等

  • and...the mathematics of, the mathematics of... balancing an object, on its...tip,

    還有平衡物品的…數學…數學運算

  • so...anyway,"The Tipping Point", by Malcolm Gladwell,

    總之 推薦Gladwell的The Tipping Point

  • audible.com, supports minute physics.

    還有我們的贊助商 audible.com

  • Without them, we won't be able to do... what we do!

    少了他們 我們節目無法成功播出

  • So, thank you to audible and

    謝謝收看

  • have an audible.com/minutephysics to get your free audio book.

    下載免費有聲書請上audible.com/minutephysics

Balancing a pencil or any other tough, heavy object on its tip,

要讓鉛筆或其他堅硬重物在尖端直立

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B1 中級 中文 鉛筆 數學 地心引力 堅硬 運算 播出

一支鉛筆能平衡多久? (How Long Can You Balance a Pencil?)

  • 1986 94
    Go Tutor 發佈於 2021 年 01 月 14 日
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