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一、一类物理趣味题的快速判断问题 n只小球(或小物体)中有一只质量稍轻(或稍重)的次品,外形、颜色、大小均相同,若只有一架天平,问最多称几次就可找出来? 例如:某工厂生产了79个小零件,突然发现有一个次品,仅比正品的质量稍轻,现手边仅有一架较精密的天平,不用其它工具,最多需称几次可找出这个次品? 分析先用“穷举法”对球的个数较少问题的分析得出结论,再由此结论导出一般规律,这符合由特殊到一般的原则。例如:当球总数是2～3只时。即3~0<2,3≤3~1时,最多测1次;
First, a class of physical questions quickly determine the problem n small balls (or small objects) in a slightly lighter (or slightly heavier) defective, appearance, color, size are the same, if only a balance, ask the most How many times can I find out? For example, a factory produces 79 small parts and suddenly finds a defective product, which is only slightly lighter than the quality of the genuine product. Now there is only a more precise scale at hand, and no other tools are required. How many times can we find this defective product? The analysis first uses the “exhaustion method” to analyze the problem of a small number of balls and draws conclusions. From this conclusion, the general law is derived. This is in line with the principle of special to general. . For example: When the total number of balls is 2 to 3 only. That is, when 3~0<2,3≤3~1, it is measured up to 1 time;