That never changes if there is no air drag or air friction of any kind.

它未曾变过,如果没有空气阻力,或任何摩擦力。

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Wind movements are also modified in cities because buildings increase the friction on air flowing around them.

风向在城市里也会改变，因为建筑物增加了它们周围流动的空气的摩擦力。

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The flick of a finger is enough to make a balloon accelerate away. When moving, it has little momentum and even the friction of the air quickly slows it up.

一根手指的弹击足够使一个气球加速离去，当气球运动时，一点动力，甚至空气的摩擦力可以很快使它慢下来。

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Surprisingly, in the eighteenth century, horologists were already using air friction to regulate the speed of minute repeaters.

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Taking this traditional idea of using air friction and refining it to control the speed of automatic winding, Urwerk has replaced the traditional rotating mechanisms of the past with miniature twin turbines that can be seen spinning on the back of the watch and are connected to the rotor.

FORBES: Jackie Chan, Kwon Sang-Woo and Urwerk Star in Chinese Zodiac

Traveling through the sky at a few kilometers per second, friction with the air can cause the meteor to break up into several pieces.

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