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纵观2017高考新课标卷Ⅰ物理选择题的第21题,可以说是最难的一个,此题是静力学中一个有关三力的动态平衡问题.此题如下:如图1,柔软轻绳ON的一端O固定,其中间某点M拴一重物,用手拉住绳的另一端N,初始时,OM竖直且MN被拉直,OM与MN之间的夹角为α(α>π/2).现将重物向右上方缓慢拉起,并保持夹角α不变.在OM由竖直被拉到水平的过程中().
Throughout the 2017 college entrance examination new curriculums Volume I physical multiple choice question 21, can be said to be the most difficult one, this problem is static in a dynamic balance of three forces. This question is as follows: Figure 1, soft light One end of the rope ON is fixed, a certain point M is connected to a heavy object, and the other end N of the rope is pulled by hand. Initially, the OM is vertical and the MN is straightened. The angle between OM and MN is α > π / 2). Now pull the weight up slowly to the upper right and keep the angle α constant.