Work Energy and Power - Result Question 9
11. A force of $250 N$ is required to lift a $75 kg$ mass through a pulley system. In order to lift the mass through $3 m$, the rope has to be pulled through $12 m$. The efficiency of system is
[2001]
(a) $50 %$
(b) $75 %$
(c) $33 %$
(d) $90 %$
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Answer:
Correct Answer: 11. (b)
Solution:
- (b) Efficiency $=\frac{\text{ output work }}{\text{ input work }}$
i.e., Efficiency,
$=\frac{75 g \times 3}{250 \times 12}=\frac{75 \times 10 \times 3}{250 \times 12}=0.75=75 %$
