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Physics Guru is an online education and competitive examinations preparation portal founded by Manish Verma, an IIT Madras alumnus, providing learning resources for competitive examinations.

The emphasis is on conceptual understanding, analytical thinking and problem solving rather than simply memorising formulas and standard methods.

The objective is to help students understand what they are learning and develop the ability to solve problems they have not seen before.

Water falls from a height of 60 m at the rate of 15 kg/s ....

Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? ($g=10 m/s^2$)

(1) 10.2 kW
(2) 8.1 kW
(3) 12.3 kW
(4) 7.0 kW

Solution

Loss in PE per sec. $=15 \times 10 \times 60 W$

Due to 10% loss, 90% of the above is converted into electric power.

So, power generated $=0.9 \times 15 \times 10 \times 60 = 8100 W = 8.1 kW $

Answer: (2)