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A raindrop of mass 1.00 g falling from a height of 1 km hits the ground with a speed of 50 ms-1. Calculate(a) The loss of P.E. of the drop.(b) The gains in K.E. of the drop.(c) Is the gain in K.E. equal to loss of P.E.? If not why.Take g = 10 ms-2 |
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Answer» Given mass of rain drop, (m) = 0.001 kg = 1.0 × 10-3 kg Height, h = 1 km = 1000 m Speed, v = 50 m/s, u = 0. (a) Loss of PE = mgh = 1 × 10−3 × 10 × 103 = 10 J (b) Gain in KE = \(\frac{1}{2}\)mv2 = \(\frac{1}{2}\) × 10−3 × 2500 = 1.25 J (c) No, Because a part of PE is used up in doing work against the viscous drag of air. |
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