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JEE Main 2014 (11 Apr, Shift 1) · Conservation of Energy

Conservation of Energy question from JEE Main 2014 (11 Apr, Shift 1)

Q34JEE Main 2014 · 11 APR · SHIFT 1Medium

Conservation of Energy

The average mass of rain drops is 3.0 ×\times 10−-5 kg and their average terminal velocity is 9 m/s. Calculate the energy transferred by rain to each square meter of the surface at a place which receives 100 cm of rain in a year.

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Answer: (b)

  1. 100 cm of rain on 1 m21\text{ m}^2: volume =1 m3= 1\text{ m}^3, mass =1000 kg= 1000\text{ kg}.
  2. All drops reach the ground at terminal speed 9 m/s9\text{ m/s}; drop size does not matter.
  3. E=12Mv2=12×1000×81E = \frac{1}{2}Mv^2 = \frac{1}{2} \times 1000 \times 81
  4. E=4.05×104 JE = 4.05 \times 10^4\text{ J}. So the answer is (b).
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