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Question
What is a block and tackle system of pulleys? What precautions would you observe while rounding the string so that the effort is applied in the downward direction?
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Solution
A block and tackle system of pulleys consists of two blocks of pulleys, each block having one or more than one pulleys. The upper block of pulleys is fixed to a rigid support and the lower block of pulleys is movable. The number of pulleys in the movable block is either equal or one less than the number of pulleys in the fixed block.
While rounding the string, its one end is attached to the hook of the movable block if the number of pulleys in the fixed block is more than that in the movable block or to the hook of the fixed block if the number of pulleys is the same in both the blocks.
RELATED QUESTIONS
A boy uses a single fixed pulley to lift a load of 50 kgf to some height. Another boy uses a single movable pulley to lift the same load to the same height. Compare the effort applied by them. Give a reason to support your answer.
Fill in the blank:
A pulley is used to change ........................
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A pulley is used because of it
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Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
The mechanical advantage of an ideal single movable pulley is ______.
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Draw the diagram of a single movable pulley and obtain its mechanical advantage, velocity ratio, and efficiency.
