The drag force acts in the opposite direction to the path of the ball.

阻力方向与球的运行方向相反。

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When the pilot's control force acts only to deflect the tab, and not the main surface, it is designated a servo tab.

当驾驶员的操纵力仅使调整片偏转而不作用于主操纵面时，称为伺服调整片。

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The drift move of field has generality: Any eddy field may have a drift move of field in the nature when the external force acts.

场的漂移运动可以作一般性推广：自然界中在外力作用下任意涡旋场可以产生场的漂移运动。

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Gravity is one force that acts on a body without the source of the force actually touching it.

引力是一种受力物体收到了力的作用,但却没有接触施力物体的力

耶鲁公开课 - 基础物理课程节选

I've got to find them by experimenting, by putting other bodies and seeing how they react and then finding out what's the force that acts on a body when it's placed in this or that situation.

我得通过实验找出这些力,我会增加其它物体,观察其反应,求出当它处在这种或者那种情况下时,作用在物体上的力

耶鲁公开课 - 基础物理课程节选

"The Air Force aggressor acts as a hacker coming against us and we see how our defensive plan measured up, " said Lt.

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