The given figure shows a block and tackle system of pulleys used to lift a load. When the load is pulled up by a distance 1 m, how far does the effort end move?
Given displacement of load dL=1 m
The tension in the string is as shown below:
Here the load is being supported by 4 segments of the string i.e. number of strands supporting the load = 4
So, load (L) = 4T and Effort (E) = T
In a system of 4 pulleys, if the load moves up through a distance of 1 m, each segment of the string supporting the load moves through the distance of 1 m. The number of segments of the same string moving up will be 4. This means that the total distance moved by the string is 4×1, which is the distance moved by the end of the string that represents the effort.
i.e., If dL=d and dE=nd
Here, dL=1 m and n = 4.
Hence, dE=4×1=4 m