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课本关于研究功的原理演示实验,笔者在实践中觉得有如下的缺陷: (1)原实验中除了用尺测量砝码提升的高度h和手移动的距离s外,砝码重和手的拉力F均由计算得出,使这个实验大为逊色。 (2)计算杠杆的动力时,必须测定动力臂和阻力臂,测量极不方便。 (3)实验中忽略了杠杆重、动滑轮重,这是出于因实验误差而得不到任何机械不能省功的结论的考虑,这种想法是不科学的。其实在允许实验误差范围内,实验还是可以得到正确结论的。由于这一忽略,反而造成学生一些误解、疑惑。
Textbook Demonstration experiment on research work, I believe in practice that the following defects: (1) In addition to using the ruler to measure the height of the weight lifting h and the distance of the hand movement s, the weight of the weight and hand pull F is calculated, making this experiment much worse. (2) When calculating the power of the lever, the power arm and the resistance arm must be measured, and the measurement is inconvenient. (3) The weight of the lever and the weight of the moving pulley were neglected in the experiment. This is due to the fact that due to experimental errors, the conclusion that no machinery can’t save the work is considered. This idea is unscientific. In fact, within the scope of the allowable experimental error, the experiment can still be correctly concluded. Due to this neglect, students were misunderstood and confused.