摩擦力存在的条件有二:一是物体间有相对运动或运动趋势,前者为滑(滚)动摩擦,后者属静摩擦;二是物体间要相互接触,此二条件是必要条件,不是充分条件,从课本中已知,滑动摩擦力大小取决于压力和接触面粗糙程度,记为N、μ,然而,具体的实际问题常使许多同学思维步人误区. There are two conditions for friction: First, there are relative movements or movements between objects. The former is sliding (rolling) dynamic friction, the latter is static friction; the second is the contact between objects, these two conditions are necessary conditions, not sufficient conditions From the textbooks, it is known that the magnitude of sliding friction depends on the pressure and the roughness of the contact surface, which is denoted as N, μ. However, specific practical problems often make many students think wrongly.