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很偶然的一次机会,我遇到这样一个问题: 在一口枯井里有一重物,现有一匹马,一根绳子,两只滑轮,欲把重物从井里吊出,如图1所示,马在A端向右拉,井里的重物逐渐图1上升,绳子与水平线MN的夹角α逐渐减小.但
It was a chance that I encountered such a problem: There was a heavy object in a dry well. There was a horse, a rope, and two pulleys. They wanted to lift the heavy object out of the well, as shown in Figure 1. The horse pulls to the right at the A end, the weight in the well gradually increases in Figure 1, and the angle α between the rope and the horizontal line MN gradually decreases.