Advertisements
Advertisements
प्रश्न
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?
Advertisements
उत्तर
The load lifted would be a maximum when conditions are ideal. Since this set-up uses three strands of string, the load gets raised only through 1/3rd of the distance through which the effort moves.
Hence,
Velocity ratio =`("Distance moved by the effort")/("Distance moved by the load")`
`=1/(1//3)=3.`
Under ideal conditions, V.R. = M.A.
Hence, Ideal M.A. of the set-up = 3.
∴ Maximum load that can be lifted = Effort × 3 = 100 N × 3
= 3000 N.
Under actual conditions, M.A. =`"Load"/"Effort"`
=`(2700"N")/(1000"N")`
= 2.7
Efficiency = `"M.A."/"V.R."=2.7/3`
= 0.9 = 90%.
संबंधित प्रश्न
What is the mechanical advantage of an ideal pulley?
Solve the following numerical problem.
What effort will be required to lift a load of 500 N by a single movable pulley? [Hint: Mechanical advantage of a single movable pulley is two].
Define the following term in reference to a gear system of Driving gear ?
Give two reasons why the efficiency of a single movable pulley system is not 100%.
A block and tackle pulley system has a velocity ratio 5. Draw a labelled diagram of this system. In your diagram, indicate clearly the points of application and the directions of the load and effort.
Give reason for the following:
In case of a block and tackle system, the mechanical advantage increases with the increase in the number of pulleys.
What is a block and tackle system of pulleys?
A type of single pulley is very often used as a machine even though it does not give any gain in mechanical advantage. For what purpose is such a pulley used?
What is a block and tackle system of pulleys? What precautions would you observe while rounding the string so that the effort is applied in the downward direction?
A pulley system has a velocity ratio of 4 and an efficiency of 90%. Calculate:
(i) the mechanical advantage of the system.
(ii) the effort required to raise a load of 300 N by the system.
