摩擦力方向的判断是学生学习的难点.教科书中是这样描述摩擦力的方向:摩擦力的方向总是沿着接触面并且跟物体相对运动趋势或相对运动方向相反.摩擦力方向的判断常用以下几种方法.1用定义法判断摩擦力方向用定义法判断摩擦力的方向,首先要明确相对运动与 The judgment of the direction of friction is difficult for students to learn.The textbook describes the direction of friction as follows: the direction of friction always follows the contact surface and is opposite to the relative or opposite direction of the object. Several methods .1 to determine the direction of friction by the definition method to determine the direction of the definition of friction, we must first clear the relative movement and