The slightest motion of a patient in bed creates friction between skin and sheets and results in loss of cells from the skin's outermost layer.

卧床病人最轻微的活动就会在皮肤和床单之间产生摩擦力，结果就会引起皮肤最外层脱落。

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The general low level of friction on ice allows a skater to glide along the surface smoothly without friction stopping the motion as soon as it's begun.

冰面上摩擦力通常较低，这使得滑冰选手一俟启动，就能不受摩擦力牵绊，顺畅滑翔冰面。

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If there were no friction, an object in (motion) would never come to a rest.

如果没有摩擦力，那么一个在运动的物体永远也不会停下来。

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Its two high-speed electric motors operate as one but can act independently (and incidentally, by using reverse torque instead of friction for braking, the motors convert the energy of your motion to help replenish the battery).

FORBES: A Standing Ovation