按照圖的要求畫出滑輪組的繞繩方法(不計滑輪重、繩重及摩擦)

試題分析：動滑輪被幾根繩子承擔，拉力就是物體和動滑輪總重的幾分之一（1）F=，由4段繩子承擔滑輪的重；（2）F=，由5段繩子承擔滑輪的重．

點評：滑輪組設計原則可歸納為：奇動偶定；一動配一定，偶數(shù)減一定，變向加一定．
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