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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A testing system was designed and implemented to figure out the friction drag of an underwater axisymmetrical vehicle model.

为了研究轴对称回转体水下航行器模型所受到的壁面摩擦阻力，设计并实施了一套测试系统。

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Experimental and analytical results show that the system can be used to study the friction drag of the vehicle models at certain speed range, which full-fills the design demand.

试验和分析结果表明，该系统在一定的速度范围内可以有效地测试航行器模型所受摩擦阻力，满足了设计要求。

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But we all know that the reason things come to a halt when you push them is, there eventually is some friction or drag or something bringing them to rest.

但我们都知道,推完之后会停下来的原因就是,最后还是有某种摩擦或者拖拽,或者别的什么使得物体静止下来

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With little inertia, friction or drag, the wheel can be spun up to speed in a trice, and then made to dump its rotational energy back into the car's transmission in seconds.

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