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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
The pulley system has drawn lifts a load of 150 N when an effort of 60 N is applied. Find its mechanical advantage.
State whether the following statement is True or False.
A pulley changes the direction of force.
What is a pulley?
Answer the following in detail.
How does a pulley make work simpler?
The diagram below shows a pulley arrangement.
(i) In the diagram, mark the direction of the forces due to tension, acting on the pulley P.
(ii) What is the purpose of the pulley Q?
(iii) If the tension is T newton, deduce the relation between T and E.
(iv) Calculate the velocity ratio of the arrangement.
(v) Assuming that the efficiency of the system is 100%, what is the mechanical advantage?
(vi) Calculate the value of E
What is a block and tackle system of pulleys?
Give a reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
(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 a single movable pulley system, a load of 125 kgf is lifted by an effort of 75 kgf. Find the percentage efficiency of system.
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)
