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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
What is the mechanical advantage of an ideal pulley?
Define the following term in reference to a gear system for Gain in speed ?
Draw a diagram of a combination of three movable pulleys and one fixed pulley to lift up a load. In the diagram, show the directions of load, effort and tension in each strand. Find:
- mechanical advantage,
- Velocity ratio and
- efficiency of the combination in ideal situation.
What is a block and tackle system of pulleys?
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
In the alongside the figure of two pulleys shown a system in which one pulley is fixed and the other is movable. What is the velocity ratio of the system?
An effort of 600 N is needed to lift a weight of 1000 N. What are the mechanical advantage and efficiency of the pulley system?
Draw the diagram of a single movable pulley and obtain its mechanical advantage, velocity ratio, and efficiency.
Draw a diagram showing a block and tackle system of 4 pulleys.
(i) State, how many strands of tackle support the load?
(ii) Draw arrows to represent tension in each strand.
(iii) Find the mechanical advantage of the system, stating the assumptions made.
(iv) If the load is pulled up by a distance 1m, how much does the effort end move?
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.
