百科知識視頻之煎蛋小學(xué)堂18 用手指尖平衡鉛筆的最佳方法

Balancing a pencil or any other top-heavy object on its tip is quite a precarious task.It's easy to see why top-heavy objects are unstable.They just want to fall down.Any little nudge will put it off balance.With gravity happy to pull its center of mass even more off balance.And the more off-balanced it is.the more gravity pulls until...

將鉛筆或任何頭重的物體平衡在尖端都是在拼人品。顯然 頭重的物體很不穩(wěn)定，它們就喜歡趴體。極小的推力就會使其失衡。而重力很樂意使其質(zhì)心更偏離平衡點，越偏離平衡 重力作用越明顯 直到...

Physicists call this kind of tipping an inverted pendulum,because it's kind like an upside down pendulum,And careful mathematical analysis of inverted pendulums will tell you the obvious:they are really unstable.

物理學(xué)家將這種尖端稱為“倒擺”，因為它很像是顛倒的擺錘。對倒擺精確數(shù)學(xué)分析的結(jié)果也顯而易見，它們非常不穩(wěn)定.

In fact,these equations predict that if a perfectly balanced pencil with a perfectly sharp tip were to get nudged off balance by just 1/10,000 of the width of an atom,it would take only 3 seconds to fall over.There are indeed acrobats who can balance poles with other acrobats on top.and robots that can balance and,catch and throw upright sticks and people who make seemingly impossible artistic rock stacks,But in all these cases,keeping the objects balanced either requires an active stabilization effort,or else carefully taking advantage of the fact that the balancing point isn't actually a point.

實際上 這些等式說明，如果一個尖端極其銳利 處于完美平衡的鉛筆受到推力失衡，偏離原子長度的萬分之一，倒下只需不到三秒。的確有雜技演員可以平衡頂端站人的桿子，有機(jī)器人可以平衡 拋擲或接住豎直棒，有人可以堆出看似不可能的石堆。但這些情況中 保持物體平衡，要么需要動態(tài)平衡支持，要么謹(jǐn)慎地利用算不上點的“平衡點”。

So the question is this:Can you balance a pencil sharpened to a perfect single atom wide tip on its tip,without active stabilization?Well to start,you'd better get rid of all the air bumping on the sides of the pencil.since the kinetic energy of a typical oxygen molecule is enough to destabilize the pencil.

那么 問題在此，你能否將一只鉛筆平衡在其原子大小的尖端，而不需要動態(tài)平衡嗎?一開始 你最好排空碰撞著鉛筆各面的空氣。因為單是氧原子的動能就足以讓鉛筆失衡.

Remember,if the pencil gets off center by even 1/10,000 the width of an atom,it will fall down in under 3 seconds.And you'd better cool the pencil and table down as close to absolute zero as you can,since the thermal jiggling of their atoms when they are hotter will similarly jiggle the pencil off balance.

記住 如果鉛筆偏離平衡點萬分之一原子的距離，它就會在3秒內(nèi)倒下，你也最好將鉛筆和桌子盡可能地冷卻到絕對零度。因為原子溫度較高時的熱振動，也會將鉛筆“振”倒。

But even then,matter at very small scales has a spread out wave-like nature,which means you can't have both the pencil perfectly upright and not moving at the same time.And while this quantum effect is never a real life inhibitor of precarious pencil balancing,it means you never even could succeed.

即使這樣 十分微小的物質(zhì)具有類似于波的本質(zhì)，也就是說 鉛筆完全豎直與保持平衡不動，不可同時兼得。盡管量子效應(yīng)不會對你拼人品平衡鉛筆帶來真實影響。者卻意味著 你永遠(yuǎn)做不到。

However,it's still fun to see how long you can keep a pencil balanced on a finger tip.The shorter the pencil,the harder it is,My best time for a standard 19cm pencil was 1.3s.Think you can beat it?

不過 看看你能用指尖平衡鉛筆多長時間也很有意思。鉛筆越短 難度越大。我的標(biāo)準(zhǔn)19厘米鉛筆最好記錄是1。3秒。你行你上啊?