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प्रश्न
What is a block and tackle system of pulleys?
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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 pulley. 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 to or one less than the number of pulleys in the fixed block.
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संबंधित प्रश्न
What is a pulley?
What should be the gear ration of a car : equal to 1, less than 1 or greater than 1, while gaining speed on the road ?
What is a single movable pulley? What is its mechanical advantage in the ideal case?
Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
Give a reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
State two reasons, why the efficiency of a pulley system is not 100 percent?
The alongside figure shows the combination of a movable pulley P1 with a fixed pulley P2 used for lifting up a load W.
(i) State the function of the fixed pulley P2.
(ii) If the free end of the string moves through a distance x, find the distance by which the load W is raised.
(iii) Calculate the force to be applied at C to just raise the load W = 20 kgf, neglecting the weight of the pulley P1 and friction.
Draw a diagram showing a block and tackle system of 4 pulleys.
(i) State, how many strands of tackle support the load?
(ii) Draw arrows to represent tension in each strand.
(iii) Find the mechanical advantage of the system, stating the assumptions made.
(iv) If the load is pulled up by a distance 1m, how much does the effort end move?
State one advantage of single movable pulley.
