A bucket of water weighing $6 N$ needs to be lifted through a single movable pulley system by a boy. How much effort should he apply to pull the bucket up if the pulley system has an efficiency of $75 %$ ?

9 N

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4 N

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6 N

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10 N

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Solution

The correct option is B $4 N$
Given:
Load, $L = 6 N$
Efficiency, $η = 75 %$
Since, it is a single movable pulley system,
Velocity ratio, $VR = 2$
We know that,
$η = \frac{MA}{VR} \times 100$
$75 = \frac{MA}{2} \times 100$
$⟹ MA = 1.5$
And, $MA = \frac{Load}{Effort}$
$1.5 = \frac{6}{Effort}$ $⟹ Effort = 4 N$

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A bucket of water weighing 6 N needs to be lifted through a single movable pulley system by a boy. How much effort should he apply to pull the bucket up if the pulley system has an efficiency of 75%?

The correct option is B 4 NGiven: Load, L=6 N Efficiency, η=75% Since, it is a single movable pulley system, Velocity ratio, VR=2 We know that, η=MAVR×100 75=MA2×100 ⟹MA=1.5 And, MA=LoadEffort 1.5=6Effort ⟹Effort=4 N

A bucket of water weighing $6 N$ needs to be lifted through a single movable pulley system by a boy. How much effort should he apply to pull the bucket up if the pulley system has an efficiency of $75 %$ ?