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气体内迁移现象及其规律在现代科学技术中应用相当广泛,气体内迁移现象包括内摩擦、热传导和扩散。 国内现行普通物理教材在推导气体内迁移现象公式时总把无规则运动的气体分子分成三队,其中一队平行于z轴,即沿小面积ds的法线方向运动(如图一),另外两队各平行于x轴和y轴运动(图中未示出)。这种假设使学生不易理解。同时根据此假设而求出在dt时间内通过ds的分子数dN =1/6n_ovds·dt,尤其不严密。为此,作者提出:
The phenomenon of gas migration and its laws in the modern science and technology is widely used, the gas migration phenomena include internal friction, heat conduction and diffusion. The common physical textbooks in our country always divide irregular gas molecules into three groups when deducing the formula of gas migration phenomenon. One of them is parallel to the z-axis, that is, along the normal direction of a small area ds (Figure 1). In addition, The two teams each run parallel to the x-axis and the y-axis (not shown). This assumption makes it harder for students to understand. At the same time, the number of molecules dN = 1 / 6n_ovds · dt passing through ds in dt time is obtained according to this assumption, especially not strictly. To this end, the author put forward: