牛顿第二定律是牛顿运动定律的核心内容,也是动力学的核心规律,同时也是高考试题中经常会涉及的内容.同学们在刚学习时,甚至相当数量的同学在高三第一轮复习后,在动力学问题中涉及到符号问题时,仍然容易出错,这是个难点.有关符号问题,现总结如下: Newton’s second law is the core content of Newton’s law of motion, and it is also the core law of dynamics. It is also the content often involved in high test questions. When the students were just learning, even a considerable number of classmates reviewed after the first round of the third year. When it comes to symbolic issues in dynamic problems, it is still easy to make mistakes. This is a difficult point. The symbolic issues are summarized as follows: