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प्रश्न
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?
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उत्तर
Given: L = 360 kgf, E = ?, Efficiency = 60% = 0.6,
Velocity ratio = No. of pulley in the system = 3.
Mechanical advantage (M.A.) = V.R. × Efficiency
= 3 × 0.6
= 1.8
But, M.A. =`"Load(L)"/"Effort(E)"`
∴ Effort (E) =`"Load(L)"/"M.A."`
= `360/1.8`
= 200 kgf.
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.
Is the above pulley system an ideal machine or not?
Fill in the blank:
A pulley is used to change ........................
What is the justification for using the pulley then ?
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.
Answer the following in short.
Explain the various functions that a machine can perform.
(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.
What is a pulley?
Draw the diagram of a single movable pulley and obtain its mechanical advantage, velocity ratio, and efficiency.
