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
A pulley system with VR = 4 is used to lift a load of 175 kgf through a vertical height of 15 m. The effort required is 50 kgf in the downward direction. (g = 10 N kg-1)
Calculate:
- Distance moved by the effort
- Work done by the effort
- M.A. of the pulley system
- Efficiency of the pulley system
A block and tackle system has V.R. = 5.
Draw a neat labeled diagram of a system indicating the direction of its load and effort
What is a single movable pulley? What is its mechanical advantage in the ideal case?
The diagram below shows an arrangement of three pulleys A, B, and C. The load is marked as L and the effort as E.
- Name the Pulleys A, B, and C.
- Mark in the diagram the directions of load (L), effort (E) and tension T1 and T2 in the two strings.
- How are the magnitudes of L and E related to the tension T1?
- Calculate the mechanical advantage and velocity ratio of the arrangement.
- What assumptions have you made in parts (c) and (d)?
What is a block and tackle system of pulleys?
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.
Name the type of single pulley that can act as a force multiplier. Draw a labeled diagram of the pulley mentioned by you.
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?
_______ is a machine made up of wheel and rope.
A pulley is a machine made up of a ______.
