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JEE Main 2022 (28 Jun, Shift 2) · Gravitational Potential & Energy

Gravitational Potential & Energy question from JEE Main 2022 (28 Jun, Shift 2)

Q16JEE Main 2022 · 28 JUN · SHIFT 2Medium

Gravitational Potential & Energy

Water falls from a 40 m high dam at the rate of 9 $\times$ 104 kg per hour. Fifty percentage of gravitational potential energy can be converted into electrical energy. Using this hydroelectric energy number of 100 W lamps, that can be lit, is:

(Take g = 10 ms ${}^{-2}$ )

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Answer: (b)

Mass flow rate: $\frac{9\times10^{4}}{3600} = 25$ kg/s
PE released per second: $25 \times 10 \times 40 = 10^{4}$ W
Electrical power $= 50\% \times 10^{4} = 5000$ W
Number of lamps $= \frac{5000}{100} = 50$
So the answer is (b) 50.

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