A combination of a movable pulley P1 with a fixed pulley P2 is used for lifting up a load W. If the free end of the string moves through a distance x, find the distance by which the load W is raised.
Considering the above figure,
The string that is moving through pulley P1 and P2 are same and we assume that the string is inextensible.
As the thread attached to the pulley P1 has to move equally on both the sides of the pulley, therefore if the free end of the string moves a distance of x then the load attached to P1 moves through a distance x2.