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प्रश्न
The mechanical advantage of an actual pulley is less than one. Give a reason. What is the justification for using the pulley then?
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उत्तर
In an actual pulley due to friction, the mechanical advantage is less than 1 (i.e. the effort is more than the load).
The reason for using the pulley when its mechanical advantage is equal to 1 or less than 1 is that the pulley allows us to apply the effort downwards i.e. in a convenient direction. To raise a load directly upwards is difficult. But with the help of a pulley, the effort can be applied in the downward direction to move the load upwards. One can hang on it to make use of his own weight also in order to apply the effort.
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संबंधित प्रश्न
State two functions of a machine.
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.
Answer the following in detail.
How does a pulley make work simpler?
Differentiate between a single fixed pulley and a single movable pulley.
Define the following term in reference to a gear system of Driving gear ?
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.
In the case of a block and tackle arrangement, the mechanical advantage increases with the number of pulleys. Explain.
The alongside figure shows the combination of a movable pulley P1 with a fixed pulley P2 used for lifting up a load W.
(i) State the function of the fixed pulley P2.
(ii) If the free end of the string moves through a distance x, find the distance by which the load W is raised.
(iii) Calculate the force to be applied at C to just raise the load W = 20 kgf, neglecting the weight of the pulley P1 and friction.
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.
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?
