大家知道,弹力产生的原因、静摩擦力方向判断问题分别是弹力的重点和摩擦力的难点.如何用简单的实验来直观理解弹力产生的原因和静摩擦力方向,笔者根据多年教学经验发现用毛刷便能达到这一目的. As we all know, the cause of elasticity and the direction of static friction are respectively the focus of elasticity and the difficulty of friction. How to intuitively understand the cause of elasticity and the direction of static friction using simple experiments. The author found the brush based on years of teaching experience. This will be achieved.