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• The earth spins once per day which means that if you live at the equator,

地球每天會自轉一圈，也就是說假如你住在赤道上，

• the surface of the earth with you on it is moving around a thousand miles per hour to the east relative to the center of the Earth.

相對於地球軸心，赤道表面大約每小時會以一千英哩的速度向東自轉

• Even at 45 degrees latitude, the Earth's surface is moving 700 miles per hour to the east.

即使在緯度45的地區，地球表面會以大約每小時700英哩的速度向東自轉

• So it kind of seems like it should be faster for airplanes to fly west.

所以看起來飛機若向西飛行會比較快

• I mean their destination is literally spinning towards them.

意思是說：飛機的目的地確實地朝著飛機旋轉而靠近

• At the same time, however, they're spinning away from their destination.

然而同時，飛機也會被自轉而遠離他們的目的地

• When we say the earth is going a thousand miles per hour to the east

當我們說地球每小時以一千英哩向東自轉

• that means that the ground, and airplanes on the ground, and even the air above the ground are also moving a thousand miles per hour to the east.

也就是指地表、地表上的飛機、甚至地表上方的空氣都是以每小時以一千英哩向東自轉

• For an airplane to get anywhere, it has to start moving relative to the ground and through the air, at something like a hundred or so miles per hour.

對一架要往任何一處飛行的飛機，他必須在空中以相對地表約每小時一百多英哩飛行

• So when it flies east, it's actually moving a thousand plus a hundred mile an hour to the east.

所以當飛機向東飛行時，它的飛行速度其實是每小時一千英哩加上一百英哩向東飛行

• And when it flies west, it's actually moving a thousand minus a hundred miles an hour to the east

當飛機向西飛行時，它的飛行速度其實是每小時一千英哩減掉一百英哩向東飛行

• Yes! To go west, you go east just slower than the Earth is going east.

沒錯，若要往西飛行，你的飛機的確是往東在飛，只是飛得比地球往東自轉的速度還慢

• Unless you're within 10 or so miles of the poles in which case a brisk westward walk will take you legitimately west.

除非你是位在距離地軸10多英哩的地方，在那你就算輕鬆地向西行走，你的方向的確還是會向西前進

• That said a plane do often take different amounts of time to fly the same route in different directions.

所以說呢，就算飛機是在兩個地點間的同一條路線飛行，飛行的方向經常會影響飛行時間

• Because of wind in the upper atmosphere like the jet stream that they either have at their tail or have to fly into.

因為在平流層中的風，例如高速氣流(jet stream)，無論這樣的氣流是在機尾後端，或是飛機即將要飛入

• The prevailing direction of these winds is largely caused by the Coriolis effect,

這些風的現行方向很大部分是被科氏力所影響

• which is caused by the fact that different parts of the Earth are moving east at different speeds,

主要是因為地球的不同地區其向西移動的速度不同，因而造成科氏力，

• which happens because the Earth is round and spinning.

而又因為地球是橢圓狀且會自轉，才會造成各地區的旋轉速度不同。

• So airplane travel times are influenced by the rotation of the Earth, just not in a straightforward way.

因此地球的自轉其實是會影響飛行時間的，只是不那麼直觀而已

• This video is supported by audible.com the leading provider of audio books across all types of literature including fiction, non-fiction, and periodicals.

這部影片是由有聲書領導者audible.com所贊助支持的，他們在各種類別的文學中，例如科幻、非科幻、期刊等等都具領先地位！

• If you're at audible.com/minutephysics, you can try audible free for 30 days.

如果你造訪audible.com/minutephysics網站，你可以試用三十天

• I highly recommend the book K2 by Ed Viesturs and David Roberts,

我非常推薦K2這本書，作者是Ed Viesturs和David Roberts

• about climbing the second highest mountain on Earth and all the human drama the successes and failures that have unfolded on its slopes.

這是一本關於攀爬世界第二高峰時，所發生的各種戲劇化、有起有落的過程。

• Again, you can get a free 30 days trial portable at audible.com/minutephysics.

再強調一次，在audible.com/minutephysics 你可以有三十天的試用期

• And thanks to all for supporting minutephysics.

謝謝大家支持我們minutephysics

The earth spins once per day which means that if you live at the equator,

B1 中級 中文 美國腔 飛機 地球 速度 地表 小時 氣流

# 地球向東自轉，飛機往西飛為何不會比較快？

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Loïc 發佈於 2015 年 12 月 19 日