If indeed the friction coefficient is independent of surface area, then when I tilt them they should start to slide roughly at the same Angle.

若摩擦系数真的，与接触面积没有关系，那么两者下滑时的角度，应该基本相当。

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Conclusion: the attention would be played to the influence of the roughness and abrasion of the bracket slot area on friction and anchorage control in using sliding mechanics.

结论：使用直丝弓矫治技术时，应重视托槽表面粗糙、磨损对摩擦力的影响，注意支抗控制。

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The calculation of pile negative friction is a important foundation for pile foundation design when pile foundation is in large area filled up ground.

在大面积的填土地基上做桩基础，桩的负摩擦力的计算是桩基设计中的重要依据。

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Fights could break out over corporation tax breaks on foreign sales, another area of friction with Europe where America is clearly at fault.

ECONOMIST: Great stuff, but does it have the president's support?

China reiterated its opposition to "Buy American" provisions in the recently adopted U.S. stimulus legislation -- reflecting the likelihood that trade policy will remain an area of friction between the two countries.

WSJ: Clinton Praises China Stimulus, Has Hope for North Korea Relationship

The nearby Sikalima stream is another cause of friction between the Chinese-run mine and the cattle-herding community in the area, who rely on it as a source of drinking water.

BBC: China in Zambia: Jobs or exploitation?