初二物理中,研究滑动摩擦的学生实验,原来是使用摩擦计(小木块和长木板),弹簧秤,钩码等。其实验过程是用弹簧秤水平地拉着小木块在木板上匀速运动,读出弹簧秤上的读数。这个实验结果总不理想,误差较大。我们分析,产生误差的原因,一是用手拉弹簧秤,拉力不匀,小木块运动速度时快时慢,不能准确地读出弹簧秤的读数;二是手拉弹簧秤时容易抬高,力的方向与木块运动方向有一夹角;三是实验中,学生既要用手,又要观察,还要读数,分散了注意力,容易产生偶然误差。针对产生误差的原因,进行了如图所示的改进:将弹簧秤固定在小木块中间,用细线的一端与弹簧秤挂钩相接,另一端通过一可以上下调动的滑 In the second year of physics, the student experiment of sliding friction was studied, originally using a friction gauge (a small block and a long block), a spring scale, and a hook code. The experimental process is to use a spring balance to pull a small wooden block horizontally on a wooden board to move at a uniform speed and read the reading on a spring scale. This experimental result is always unsatisfactory and has a large error. We analyze the reasons for the error. First, use hand-pulled spring scales. The tension is not uniform. The speed of wooden blocks is fast and slow. It is impossible to accurately read the readings of the spring scales. Second, it is easy to lift the hand when lifting the hand. There is an angle with the movement direction of the wooden blocks. Third, in the experiment, the students need to use their hands, but also to observe, but also to read, distract attention, and easily produce accidental errors. For the cause of the error, an improvement was made as shown in the figure: The spring balance is fixed in the middle of the small wooden block, one end of the thin wire is connected with the spring balance hook, and the other end is passed through a slide that can be moved up and down.