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प्रश्न
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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उत्तर
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.
संबंधित प्रश्न
Is the above pulley system an ideal machine or not?
Select the correct alternative:
A pulley is used because of it
State if the following statement is true or false. Correct the statement if it is false.
A single movable pulley is a pulley that has its axis of rotation fixed.
The diagram below shows an arrangement of three pulleys A, B, and C. The load is marked as L and the effort as E.
- Name the Pulleys A, B, and C.
- Mark in the diagram the directions of load (L), effort (E) and tension T1 and T2 in the two strings.
- How are the magnitudes of L and E related to the tension T1?
- Calculate the mechanical advantage and velocity ratio of the arrangement.
- What assumptions have you made in parts (c) and (d)?
Write two uses of pulleys. Is pulley a force multiplier?
What is a block and tackle system of pulleys?
There is no gain in mechanical advantage in the case of a single fixed pulley. Explain, why the pulley is then used?
State two reasons, why the efficiency of a pulley system is not 100 percent?
| Meera chose to use a block and tackle system of '9' pulleys instead of a single movable pulley to lift a heavy load. |
Why should she connect more number of pulleys in the upper fixed block?
