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高中物理选修课本中“验证向心力公式”的学生实验,就实验本身来说,主要存在三个方面的不足:(1)学生用手搓动转轴,不易保持圆柱体每一次转动都恰好从半径指示器的缺口处通过,不仅难以形成匀速圆周运动,甚至难以形成圆周运动.(2)用平均法将圆柱体的运动近似处理为匀速圆周运动时,ω、F、r都应取平均值,但实验却测不出对应于ω平均值的F、r的平均值.(3)圆柱体和横杆间存在较大摩擦,致使F测量误差偏大;就实验教学与理论教学的关系而论,由匀速圆周运动验证向心力公式则不利于学生在一般意义上认识向心力公式.该实验虽然存在这些不足,但却有着原理简明、构造直观、价格便宜(由于不用电机带动)等明显优点.所以,我们在保持、发扬原实验的优点,削弱、消除其不足的指导思想下,对它进行了改进研究,使之趋于完善.
There are three major deficiencies in the student experiment of the “Verification of Concentric Forces Formula” in the high school physical elective textbook: (1) Students move their shafts by hand, and it is not easy to keep the cylinder from rotating every time. Pass through the notch of the device, not only difficult to form a uniform circular motion, and even difficult to form a circular motion. (2) When using the average method to approximate the cylinder’s movement as a uniform circular motion, ω, F, r should be averaged, but The experiment can’t measure the average value of F and r corresponding to the average value of ω. (3) There is a large friction between the cylinder and the crossbar, which causes the F measurement error to be large; for the relationship between experimental teaching and theoretical teaching, The verification of the centripetal force formula by uniform circular motion is not conducive to the student’s understanding of the centripetal force formula in a general sense. Although this experiment has these deficiencies, it has obvious advantages such as concise principle, intuitive structure, and low price (because no motor is used). Therefore, we have Under the guiding ideology of maintaining and promoting the advantages of the original experiment and weakening and eliminating its deficiencies, it has been improved and studied to make it perfect.