一、因果性牛顿第一定律指出了力和运动的关系,力不是维持物体运动状态的原因,力是改变运动状态的原因,即力是产生加速度的原因.牛顿第二定律又进一步指出了力和加速度之间的量的关系,有了力就有了加速度,若不存在力,则没有加速度.我们在判断受力问题时可以根据这一因果关系来进行分析.例1(2012年山东卷)将地面上 First, causal Newton’s first law pointed out that the relationship between force and movement, force is not the reason for maintaining the state of motion of objects, force is the reason for changing the state of motion, that force is the cause of acceleration .Newton’s second law and further pointed out that the force And acceleration between the amount of the relationship, with the force will have acceleration, if there is no force, there is no acceleration. We determine the force problem can be based on this causal relationship to be analyzed. Will be on the ground