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物理教学中会碰到这类问题:一定质量的理想气体能否完成下列过程:1、吸收热量同时体积缩小;2、内能减少而压强增加;3、吸收热量但温度降低,这些问题都可依据热力学第一定律W+Q=△E和气态方程pV/T=C来分析判定,但其中有些过程的分析较为繁琐也很抽象,现介绍一种简易直观的方法。一定质量的理想气体从状态M出发作任意变化,变化后若压强增加其状态位置一定在过M点的等压线上方,若压强减小其位置一定在等压线的下方,如图1—(1)所示。对过M点的等容线来说,凡气体在状态变化时对外做功体积膨胀者,其最终位置一定在它的右侧,凡外
In physics teaching, this type of problem will be encountered: whether a certain quality of ideal gas can complete the following processes: 1. Absorb heat while reducing the volume; 2. Reduce the internal energy and increase the pressure; 3. Absorb heat but the temperature decreases. These problems can all be solved. According to the first law of thermodynamics W + Q = △ E and the gaseous equation pV / T = C to analyze and determine, but some of the process of the analysis is cumbersome and abstract, now introduces a simple and intuitive method. A certain quality of ideal gas changes from the state M out of the attack. If the pressure increases after the change, the state position must be above the isobar of the M point. If the pressure decreases, the position must be below the isobar, as shown in Figure 1— (1) shows. For M-isometric lines, where the gas expands in volume when the state changes, its final position must be on its right side.