Q.195. System of pulleys.

Question 195.
For the arrangement of pulleys shown in the figure, find the effort P required to raise the given load (W).Assume efficiency of the system as 80%

Answer 195.
As the tension, T, is the same in all strings (taken as almost vertical),
Tension in strings below the two lower pulleyes = 2T
=> 4T = 800 and T = P
=> P = 200 N (for 100% efficient system)
=> P = 200/(0.80) = 250 N.

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