描述物理现象的各物理量之间常存在着相互依赖、相互制约的关系,当其中某个物理量发生变化时,其他物理量也将按照一定的规律发生变化,这类问题被称为动态变化问题.动态变化问题是初中物理中较难解决的一类问题,对提高学生分析解决问题的能力、培养学生的创新精神是十分有益的,近几年动态问题在中考中也越来越受到命题者的青睐.突破该类问题的关键在于以下几点:首先,要区分变量和不变量,挖掘变量间的相互关系;其次,通过统筹分析,依 There are often interdependence and mutual restraint relationships between physical quantities that describe physical phenomena. When one of the physical quantities changes, other physical quantities will also change according to certain rules. Such problems are called dynamic change problems. The problem of change is a type of problem that is more difficult to solve in the junior middle school physics. It is very useful to improve the students’ ability to analyze and solve problems and to cultivate students’ innovative spirit. In recent years, dynamic issues have also been increasingly favored by propositioners in the middle school entrance examination. The key to breaking through this type of problem lies in the following points: First, we must distinguish between variables and invariants, and mine the correlation between variables. Second, through overall analysis,