在人教版九年级物理教科书中,“对外做功内能减少”实验是作为第十三章“内能”第二节中一个重要的演示实验出现的,它是热力学知识的重要应用,也是学生理解和掌握做功改变内能的重难点。2013年新版教材中的演示实验方法是:在烧瓶中盛少量水,给瓶内打气,当瓶塞跳出时,观察瓶内的变化,如图1所示。在多年的教学实践中,笔者发现用 In the PEP 9th grade physics textbook, “Reducing External Workload” appears as an important demonstration experiment in Chapter 13, “Internal Energy,” which is important in thermodynamic knowledge Application, but also students understand and master the power to change the internal energy of the heavy difficulty. The demonstration experiment in the new 2013 teaching material is as follows: Put a small amount of water in the flask to inflate the bottle, and observe the change in the bottle when the bottle jumps out, as shown in FIG. 1. In many years of teaching practice, I found that use