“气垫导轨验证动量守恒”实验的研究

Verification of Momentum Conservation with Air Cushion Guide Rail

动量守恒定律是描述自然界物理过程的一条基本定律。为了在气垫导轨验证动量守恒的实验中精准指导学生获得有效实验数据,基于气垫导轨平台利用两滑块进行碰撞来验证动量守恒,采用碰撞前后两滑块动量的相对误差≤5%作为动量守恒的判断依据。分析了在气垫导轨粗调水平的条件下,单个滑块经过2个光电门的时间对细调的影响,发现滑块经过光电门的时间在50~200 ms时滑块过两光电门的时间差小于等于3 ms。研究了在同样的实验条件下,采用不同质量差的滑块组合进行碰撞实验,分析了质量差、碰前速度对实验结果的影响,发现两滑块碰前速度相差较大导致相对误差大于20%,获得的有效数据少;两滑块质量差较大的相对误差较小,获得的有效数据较多。分析结果表明适当增加两滑块的质量差、减小两滑块碰前的速度差有望获得较多的有效数据。

The law of momentum conservation is one of the most fundamental laws of physical processes in nature.To accurately guide students to obtain valid data in the experiment of momentum conservation verification with air cushion rail,based on the air cushion guide rail platform,the relative error of momentum of two sliders before and after collision less than or equal to 5%was set as the basis for judging the conservation of momentum.The time effect of a single slider passing through two photoelectric gates was analyzed under condition of coarse adjustment about the air cushion guide rail,and it was found that the time difference between two photoelectric gates was less than or equal to 3 ms when the slider passed through the photoelectric gate between 50 and 200 ms.Under the same experimental conditions,the collision experiment was carried out by using different mass difference sliders.The effect was analyzed about mass discrepancy and speed before collision,it was found that relative error was greater than 20%if the difference in the speed of the two sliders before collision was large,and the effective data obtained was less,the relative error with larger quality difference was smaller,and more valid data were obtained.The results showed that there is a greater probability of obtaining more valid data through appropriately increasing quality difference of two sliders and reducing the speed difference before two sliders collide.