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在2004年下半年,湖南省部份省重点中学举行的联考中,有二道看似普通,却又渗透着命题者精心设置的陷井题,错误率奇高,值得人们品味深思,下面试举例说明之题1在水平天花板下可用绳AC和绳BC悬挂重物,绳与竖直方向夹角分别是37°和53°,∠ACB=90°,如图1所示,绳AC能承受的最大拉力为100N,绳BC能承受的最大拉力为180N,重物质量过大时会使绳拉断.现挂上一个质量为14kg的重物后,(g=10m/s2,sin37°=0.6,cos37°=0.8)
In the second half of 2004, in the joint examinations held in key high schools of some provinces in Hunan Province, there were two seemingly ordinary traps that permeated propositions carefully. The error rate was extremely high and it was worth thinking deeply. The interview example illustrates the problem 1 can be used under the horizontal ceiling rope AC and rope BC hanging weight, the cord and the vertical direction of the included angle is 37 ° and 53 °, ∠ACB = 90 °, as shown in Figure 1, the cord AC energy The maximum tensile force is 100N, and the maximum tensile force the rope BC can bear is 180N. When the weight is too large, the rope will pull off. After weighing a mass of 14kg, (g=10m/s2, sin37°) =0.6, cos37°=0.8)