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प्रश्न
Give two reasons why the efficiency of a single movable pulley system is not 100%.
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उत्तर
The efficiency of a single movable pulley system is not 100% this is because
- The friction of the pulley bearing is not zero.
- The weight of the pulley and string is not zero.
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संबंधित प्रश्न
A pulley system has three pulleys. A load of 120 N is overcome by applying an effort of 50N. Calculate the Mechanical Advantage and Efficiency of this system.
Answer the following in detail.
How does a pulley make work simpler?
Give a reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
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?
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
What is the relation between the mechanical advantage and the number of strands of string used to support the load, in a ‘block and tackle’ set-up?
A boy lifts a load of 40 kgf through a vertical height of 2m in 5s by using a single fixed pulley when he applies an effort of 48 kgf. Calculate:
(i) the mechanical advantage, and
(ii) the efficiency of the pulley. Why is the efficiency of the pulley is not 100%?
(iii) the energy gained by the load in 5s, and
(iv) the power developed by the boy in raising the load.
State one advantage of single movable pulley.
A block and tackle system of pulleys has a velocity ratio of 4.
- Draw a labelled diagram of the system indicating clearly the direction of the load and effort.
- Calculate the potential energy of the load 100 kgf lifted by this pulley to a height 5 m. (g = 10 ms−2)
