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प्रश्न
Select the correct alternative:
A pulley is used because of it
पर्याय
has the mechanical advantage greater than one
has 100% efficiency
helps to apply the force in a convenient direction
requires more effort to raise a less load.
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उत्तर
helps to apply the force in a convenient direction
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संबंधित प्रश्न
Fill in the blank:
A pulley is used to change ........................
What is a pulley?
What is the justification for using the pulley then ?
Explain how a gear system can be used to obtain Change in direction of rotation. Given one example.
In a gear system, the gear ration of the driving wheel A and driven wheel B is 10:1. To rotate the driven wheel B in the direction of driving wheel A, the driving wheel A is engaged with other wheel C. what should be the gear ratio of the wheels A and C?
Name the type of single pulley that can act as a force multiplier. Draw a labelled diagram of the pulley mentioned by you.
Give two reasons why the efficiency of a single movable pulley system is not 100%.
In which direction does the force need to applied, when a single pulley is used with a mechanical advantage greater than one? How can you change the direction of force applied without altering its mechanical advantage? Draw a labelled diagram of the system.
(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?
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.
