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(B) Given:Volume of water $V = 36 \,m^3$Time $t = 30 \,min = 30 	imes 60 \,s = 1800 \,s$Height $h = 50 \,m$Input Power $P_{	ext{in}} = 40 \,kW = 40,

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$25$

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(B) Given:Volume of water $V = 36 \,m^3$Time $t = 30 \,min = 30 	imes 60 \,s = 1800 \,s$Height $h = 50 \,m$Input Power $P_{	ext{in}} = 40 \,kW = 40,000 \,W$Density of water $ho = 1000 \,kg/m^3$Acceleration due to gravity $g = 10 \,m/s^2$Mass of water $m = V 	imes ho = 36 	imes 1000 = 36,000 \,kg$Work done to lift the water $W = mgh = 36,000 	imes 10 	imes 50 = 18,000,000 \,J$Output Power $P_{	ext{out}} = \frac{W}{t} = \frac{18,000,000}{1800} = 10,000 \,W = 10 \,kW$Efficiency $\eta = \frac{P_{	ext{out}}}{P_{	ext{in}}} 	imes 100\% = \frac{10,000}{40,000} 	imes 100\% = 25\%$

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