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प्रश्न
Give reason for the following:
The lower block of a block and tackle pulley system must be of negligible weight
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उत्तर
The lower block pulleys should be as light as possible to maximise efficiency, and lubricants should be used to reduce friction in pulley bearings.
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संबंधित प्रश्न
Answer the following in short.
Explain the various functions that a machine can perform.
Differentiate between a single fixed pulley and a single movable pulley.
What is a gear system ?
What is a block and tackle system of pulleys?
Write two uses of pulleys. Is pulley a force multiplier?
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?
(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?
Draw the diagram of a single movable pulley and obtain its mechanical advantage, velocity ratio, and efficiency.
The pulley system shown in the figure is to be used to lift a load W. If the man applying the effort cannot apply a force exceeding 1000 N, what is the maximum load that can be lifted?
The actual load that the man is finally able to lift turns out to be 2700 N. What are the values of the actual M.A., obtained, and the efficiency of the actual set-up?
A man raises a load of 360 kgf using a block and tackle system of 3 pulleys. If the efficiency of the pulley system is 60%, what effort is applied by the man?
