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An installation consisting of an electric motor driving a water pump left 75 L of water per second to a height of 4.7 m .If the molor consumes a power of 5kW , then the efficiency of the installation is 

Answer:

Explanation:

Power consumed by motor =5kW

=  $5 \times 10^{3}W$=5000W

power used in lifting water =$\frac{mgh}{t}$

 $=7.5 \times 9.8 \times 4.7 =3454.5kW$

 Efficiency = power used/ power  consumed  x 100%

  $=\frac{3454.5}{5000} \times 100=$69%