论文部分内容阅读
有一位青年教师在课堂上作天平使用的演示实验时,用天平称一金属块,先估计该金属块质量约六十克,加、退砝码的操作顺序为:50克、5克、2克、2克、1克,还不够,退5、2、2、1克,再加10克、5克、2克、2克、1克,又不够,退5克、2克、2克、1克,再加……加减砝码的操作前后有20余次之多,观测天平平衡也多达十多次。我征询他的意见:“你在加减砝码的操作顺序上有没有什么规律?”回答是:“刚才的操作好象不大合理,但课本上没有写,大学的实验课中也没有讲,反正能够称出物体质量就行了。”显然,感到不合理,但无章可循。
When a young teacher used a demo experiment in the classroom as a balance, he used a scale to weigh a piece of metal and first estimated the mass of the metal piece to be about 60 grams. The order of adding and removing the weight was: 50 grams, 5 grams, 2 Grams, 2 grams, 1 gram, not enough, back 5, 2, 2, 1 grams, plus 10 grams, 5 grams, 2 grams, 2 grams, 1 gram, not enough, retreat 5 grams, 2 grams, 2 grams , 1 g, plus ... plus and minus weights before and after the operation more than 20 times as much as the balance of observations up to 10 times. I consulted him: “Do you have any rules on the order of adding and subtracting weights?” “The answer is:” The previous operation did not seem to be reasonable, but it was not written in textbooks. Did not say, anyway, can weigh the quality of the object on the line. " Obviously, feel unreasonable, but there is no rule to follow.