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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.
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उत्तर
The ratio of load to the effort is called the mechanical advantage.
Mechanical advantage (MA) = `"Load(l)"/"Effort(E)"`
The above equation indicates that 'MA' and 'Effort' are inversely proportional.
The mechanical advantage of the single fixed pulley is 1.
For, single movable pulley = 50 kgf
:. Effort (Esingle fixed pulley) = `"Load"/(MA_"single fixed pulley")`
= `50/1 = 50` kgf
Effort (Esingle fixed pulley) = `"Load"/(MA_"single movable pulley")`
= `50/2 = 25` kgf
Therefore, the boy using a single movable pulley requires lesser effort to lift an equal load of 50 kgf when compared with the effort required by the boy using a single fixed pulley.
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संबंधित प्रश्न
Is the above pulley system an ideal machine or not?
What is a pulley?
Name a machine to change the direction of force ?
A pulley system has a velocity ratio 3. Draw a diagram showing the point of application and direction of load (L), effort (E) and tension (T). It lifts a load of 150 N by an effort of 60 N. Calculate its mechanical advantage. Is the pulley system ideal? Give reason.
The diagram below shows a pulley arrangement :
(i) Copy the diagram and mark the direction of tension on each strand of the string.
(ii) What is the velocity ratio of the arrangement ?
(iii) If the tension acting on the string is T, then what is the relationship between T and effort E ?
(iv) If the free end of the string moves through distance x, find the distance by which the load is raised.
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?
What is a pulley?
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?
