surface friction force

The more rough and jagged something is, the more easily more of its molecules will come into contact with molecules on the surface it touches, and thus the greater force of friction they will exert.

物体表面越粗糙不平，它的分子就越容易更多地与接触表面的分子相粘合，因此就会产生更大的摩擦力。

The force which must be overcome to keep one surface moving over another in known as sliding friction.

而保证一个平面沿着另一个平面相对移动的力称为滑动摩擦力。

Scientists now believe that some of the force of friction is due to attraction between the molecules of one surface and those of the surface sliding over it.

现在科学家们认为有些摩擦力是由于物体表面的分子和另一物体表面游动的分子之间的吸引力所引起的。