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Systems of Fixed and Movable Pulleys

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-106

2025-12-30

983

Systems of Fixed and Movable Pulleys. Where great weights are to be raised, systems of pulleys are used. Usually a num- ber of "sheaves" or pulleys are arranged side by side in the same block, and a single rope is passed alternately around the sheaves in two of these blocks, called the "block and tackle" (Fig. 1). Another arrangement is shown in Fig. 2. The weight is attached to the movable block A (Figs. 1 and 2), and since the rope is continuous there must be the same pull on each branch be- tween the blocks. If we let n represent the number of branches extending to the movable block (n=6 in Figs. 1 and 2), then by each branch must support 1/n of the weight;

P=W/n   _{…… (1)}