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प्रश्न
From the diagram given below. answer the question that follows:
1) What kind of pulleys are A and B?
2) State the purpose of pulley B.
3) What effort has to be applied at C just raise the load L = 20 kgf?
(Neglect the weight of pulley A and friction)
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उत्तर
1) The pulley A is a single movable pulley and B is a single fixed pulley.
2) Pulley B is a single fixed type pulley. Its purpose is to change the direction of the effort applied.
3) The effort at C is equal to the load. This is because B is a single fixed pulley and its mechanical advantage is 1. So, we have
M.A. = L/E = 1
∴ E = L = 20 kgf
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संबंधित प्रश्न
A pulley system with VR = 4 is used to lift a load of 175 kgf through a vertical height of 15 m. The effort required is 50 kgf in the downward direction. (g = 10 N kg-1)
Calculate:
- Distance moved by the effort
- Work done by the effort
- M.A. of the pulley system
- Efficiency of the pulley system
Is the above pulley system an ideal machine or not?
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.
Explain how a gear system can be used to obtain Change in direction of rotation. Given one example.
What is a block and tackle system of pulleys?
Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
(a) Fig represents an incomplete diagram of a simple string pulley system. Copy this diagram on a new page and complete it and mark where the effort must be applied to lift the load.
(b) What is the velocity ratio of this system?
(c) If the pulley system is 80% efficient and the load is 720 N, then
(i) What effort must be applied to lift the load?
(ii) What work must be done must be done in lifting the load through a distance of 2 m using this machine?
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
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?
