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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
State two functions of a machine.
What is a pulley?
What is the justification for using the pulley then ?
Draw a neat labelled diagram showing a pulley being used to lift a load. How are load and effort related in an ideal situation?
Answer the following in detail.
How does a pulley make work simpler?
Name the type of single pulley that can act as a force multiplier. Draw a labelled diagram of the pulley mentioned by you.
Draw a diagram of a single fixed pulley and obtain expressions for its:
(i) Mechanical advantage,
(ii) Velocity ratio, and
(iii) Efficiency, in the ideal case.
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?
In a single movable pulley system, a load of 125 kgf is lifted by an effort of 75 kgf. Find the percentage efficiency of system.
If the weight of the movable pulley is W, obtain the expression for MA, VR, and efficiency.
