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प्रश्न
If the weight of the movable pulley is W, obtain the expression for MA, VR, and efficiency.
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उत्तर
If the weight of the movable pulley with its frame is W, in equilibrium
E = T
L + W = 2T
Or L + W = 2E
⇒ L = 2E − W
MA =`"L"/"E"=("2E"-"W")/"E"=2-"W"/"E"`
VR will remain same, h = `"MA"/"VR"`
`=(2-"W"/"E")/2=1-"W"/(2"E")`
If W << 2E, then 2E = L
Or h = `(1-"W"/"L").`
संबंधित प्रश्न
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.
What is the mechanical advantage of an ideal pulley?
What should be the gear ration of a car : equal to 1, less than 1 or greater than 1, while ascending a hill ?
Differentiate between a single fixed pulley and a single movable pulley.
What is a block and tackle system of pulleys?
Give reason for the following:
In case of a block and tackle arrangement, the mechanical advantage increases with the increase in the number of pulleys.
Fig shown a block and tackles system of pulleys used to lift a load.
(i) How many strands of tackle are supporting the load?
(ii) Draw arrows to represent tension in each stand.
(iii) What is the mechanical advantage of the system?
(iv) When load is pulled up by a distance 1 m how far does the effort end move?
What is a block and tackle system of pulleys?
State two reasons, why the efficiency of a pulley system is not 100 percent?
Complete the table.
| S. No | Types of Simple Machine | Example |
| 1. | Pulley | |
| 2. | Wheel and axle | |
| 3. | Wedge | |
| 4. | Inclined plan | |
| 5. | Lever | |
| 6. | Screw |
