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在初中热学教学中,讲“改变物体热能的方法”时,用压缩空气引火仪来演示“对物体做功,物体的热能增加”的实验,很直观。但许多老师做此实验时都失败了。分析失败的原因,我们知道,物体要燃烧必须同时满足以下条件:(1)是可燃物,(2)达到燃点,(3)有足够的氧气助燃。根据这些条件来进行分析,实验失败的原因主要归结为两点:一是活塞漏气或者活塞下
In the teaching of junior high school thermals, when the “method for changing the thermal energy of an object” is described, the experiment of “doing work on the object and increasing the thermal energy of the object” using a compressed air pilot instrument is very intuitive. However, many teachers failed to do this experiment. The reasons for the failure of the analysis, we know that the object must be burned at the same time to meet the following conditions: (1) is a combustible, (2) to reach the ignition point, (3) there is enough oxygen to help combustion. According to these conditions to analyze, the reason for the failure of the experiment mainly comes down to two points: First, the piston leaks or the piston