Work Energy and Power - Result Question 9

11. A force of 250N is required to lift a 75kg mass through a pulley system. In order to lift the mass through 3m, the rope has to be pulled through 12m. The efficiency of system is

[2001]

(a) 50

(b) 75

(c) 33

(d) 90

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Answer:

Correct Answer: 11. (b)

Solution:

  1. (b) Efficiency = output work  input work 

i.e., Efficiency,

=75g×3250×12=75×10×3250×12=0.75=75



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