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प्रश्न
A pulley system has three pulleys. A load of 120 N is overcome by applying an effort of 50N. Calculate the Mechanical Advantage and Efficiency of this system.
उत्तर
Load = 120 N; E = 50 N; n = 3
Mechanical advantage of pulley system is
M.A. = `L/E = 120/50` = 2.4
The efficiency of the system is
`eta = ("M.A.")/("V.R.") = (2.4)/n = 2.4/3 = 0.8 = 80%`
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संबंधित प्रश्न
Name a machine to change the direction of force ?
What is a single movable pulley? What is its mechanical advantage in the ideal case?
Give reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
What is the use of a fixed pulley?
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
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
State two reasons, why the efficiency of a pulley system is not 100 percent?
A block and tackle system of pulleys has a velocity ratio of 4.
- Draw a labelled diagram of the system indicating clearly the points of application and directions of load and effort.
- What is the value of the mechanical advantage of the given pulley system if it is an ideal pulley system?
A boy lifts a load of 40 kgf through a vertical height of 2m in 5s by using a single fixed pulley when he applies an effort of 48 kgf. Calculate:
(i) the mechanical advantage, and
(ii) the efficiency of the pulley. Why is the efficiency of the pulley is not 100%?
(iii) the energy gained by the load in 5s, and
(iv) the power developed by the boy in raising the load.
Name the type of single pulley that has an ideal mechanical advantage equal to 2. Draw a labelled diagram of the pulley mentioned by you.
