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一类有创意的U形管气体问题,水银柱怎样移动?如何确定气体的状态参量?这要由两管中水银柱的长度及气体的初始状态来共同决定.并由此进行合理、正确的推断,才能实现从未知到已知的转化,顺利解决问题.由于这类问题有效地考查了“推理能力”和“分析综合能力”等,受到命题者的“青睐”.下面结合实例谈谈这类问题的解法技巧.供大家参考.一、由两管中水银柱长度推断气体柱的位置和状态.并由此顺利解决问题.例1细长的横截面积均匀的U形玻璃管,两端都开口,管内有两段水银柱封闭着一段空气柱,若气体温度是27℃时,空气柱在U形管的左侧A、B两点之间,长度为15cm.如图1所示,图中标的长度单位为cm.若保持气体的温度不变,从左侧开口处缓慢地再注入25cm长的水银柱,管内的空气柱长为多少?为了使这
A type of U-tube gas with a creative problem. How does the mercury column move? How do you determine the state parameters of the gas? This is determined by the length of the mercury column in the two tubes and the initial state of the gas. This is reasonable and correct. Inference, in order to achieve a smooth solution to the problem from the unknown to the known transformation, because such problems effectively examine the “reasoning ability” and “analysis and comprehensive ability”, they are favored by the proposition. The problem-solving technique of the class. For your reference. I. Infer the position and state of the gas column from the length of the mercury column in the two tubes. This will solve the problem. Example 1 Uniform U-shaped glass tube with a uniform cross-section Ends are open, there are two sections of mercury inside the tube closed a section of air column, if the gas temperature is 27 °C, the air column in the U-shaped tube on the left A, B between the two points, the length of 15cm. Figure 1 In the figure, the unit of the length of the mark is cm. If the temperature of the gas is kept constant, slowly refill the 25cm-long mercury column from the opening on the left side. What is the length of the air column in the tube?