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प्रश्न
What is the relation between the mechanical advantage and the number of strands of string used to support the load, in a ‘block and tackle’ set-up?
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उत्तर
The mechanical advantage is equal to the number of strands of string, used to support the load, only if the ‘block and tackle set up’ can be assumed to be ideal (absence of friction, etc.) and the lower blocks of pulleys have negligible weight. Both these conditions cannot be satisfied in actual practice. Hence, in practical situations, the M.A. of a ‘block and tackle set up’ is always less than the fire number of strands of string used to support the load.
संबंधित प्रश्न
State if the following statement is true or false. Correct the statement if it is false.
A single movable pulley is a pulley that has its axis of rotation fixed.
Differentiate between a single fixed pulley and a single movable pulley.
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.
What is a block and tackle system of pulleys?
Write two uses of pulleys. Is pulley a force multiplier?
What is a block and tackle system of pulleys?
(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 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?
A ‘block and tackle’ system used 3 pulleys in the lower block and 4 pulleys in the upper block. What is the ‘velocity ratio’ of this system? If the load is to be lifted by a person capable of applying a maximum effort of 1000 N, what is the maximum load than can be lifted under ideal conditions?
The actual maximum load that gets lifted turns out to be 6300 N. What are the values of the actual M.A. and efficiency of the set-up?
A pulley is a machine made up of a ______.
