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下面的这两道题都是我们常见的题目,都可谓是中学物理中的经典题目,也常被命题人稍作改变,出现在各类考试中,但细加分析,发现很有问题。[原题1]如图1所示,细绳的一端拴一个质量为M的小球,细绳的另一端穿过光滑小孔。在拉力F的作用下,小球在光滑水平面上做半径为R的匀速圆周运动。今将拉力的大小缓慢地增大到4F,使小球仍在
The following two questions are our common problems, can be described as a classic problem in middle school physics, but also often be a little change in the proposition, appeared in various examinations, but careful analysis and found that there are problems. [Original title 1] As shown in Figure 1, one end of the string tied to a quality of the ball M, the other end of the string through the smooth hole. Under the action of pulling force F, the ball makes a uniform circular motion of radius R on a smooth horizontal plane. Now slowly increase the size of the tension to 4F, so that the ball is still