关于摩擦力几个问题的商榷

A Discussion About Friction force

摩擦力产生机制与作功是目前力学教学中存在争议的一个知识点,该文从摩擦产生的微观机制对摩擦力产生的原因进行了剖析,明确了摩擦力产生的条件是物体间相互接触和存在相对运动或相对运动的趋势,这两个条件的存在已包含了相互挤压的因素,因此无须再将此因素作为摩擦力产生的必备条件之一。同时从力的位移和能量转化与守恒的角度讨论了一对滑动摩擦力做功的问题,指出了摩擦力做功时力的位移应是力的作用点的位移而不是力所作用的物体的质心位移,阐明了一对滑动摩擦力做功之和始终为负而不可能为零。

This paper analyzes the condition of friction force from microscopic view, and defines that friction force exists only when two bodies are in direct contact and there is relative motion or tendency of relative motion, which causes the compression between two bodies. This paper also discusses the work done by a pair of Sliding friction forces from the displacement and conversion of energy. It points out that the displacement is not the displacement of the center of mass, but the displacement of the action point of force . Finally it concludes the the work done by a pair of sliding friction forces could not be zero, but negative.