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प्रश्न
Give reason for the following:
The efficiency of a pulley is always less than 100%
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उत्तर
The two reasons are:
(a) Some effort is wasted and overcoming the friction between the strings and the grooves of the pulley.
(b) Some effort is wasted in lifting up the movable block along with the load.
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संबंधित प्रश्न
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 the mechanical advantage of an ideal pulley?
The mechanical advantage of an actual pulley is less than one. Give a reason. What is the justification for using the pulley then?
Explain the working of a gear system.
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.
Give reason for the following:
In a single fixed pulley, the velocity ratio is always more than the mechanical advantage.
What is a block and tackle system of pulleys?
If the weight of the movable pulley is W, obtain the expression for MA, VR, and efficiency.
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?
State one advantage of single movable pulley.
