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在高中物理学习中,选取典型模型,借助理想化方法可以简化问题条件,突出问题本质,便于问题的解决。然而,在理想化过程中,诸如忽略物体形状大小、让物体“缓慢”移动、空气阻力大小不计等简化处理的手段有时候也会为解题带来一些困惑,需要我们还原物体真实的运动状态及受力状态,找到困惑产生的根源,从而加深对问题的理解。下面以两道做功问题为例,来剖析理想化方法带来的困惑。例1如图1所示,均匀长直木板长L=40cm,放在水平桌面上,它的右端与桌边相齐,木板质量m=2kg,与桌面间的摩擦因数μ=0.2,今用水平推力F将其推下桌子,则水平推力至少做多少功?
In the high school physics study, the typical model is selected. With the help of the idealized method, the problem conditions can be simplified, the essence of the problem can be highlighted, and the problem can be solved easily. However, during the process of idealization, simplifying such things as omitting object shape and size, moving “slowly” objects, and reducing air resistance can sometimes bring some confusion to the problem, and we need to restore the real object Exercise status and stress state, find the root causes of confusion, thereby deepening understanding of the problem. The following two work problems as an example to analyze the idealization of the confusion. Example 1 As shown in Fig. 1, the length L = 40cm of an even long straight wood is placed on a horizontal tabletop. Its right end is aligned with the table edge. The quality of the wooden board is m = 2kg. The level of thrust F push it down the table, the level of thrust at least how much work?