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A raindrop of mass `1g` falling from a height of `1km` hits is the ground with a speed of `50 ms^(-1)`. Which of the following statements is correct? `("Taking" g= 10ms^(-2))`. |
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Answer» Given, mass of the rain drop(m)=100g =`1xx10^(-3)kg` Height of falling(h)=`1km=10^(3)m=g=10m//s^(2)` Speed of the rain drop(v)=50m/s (a) Loss of PE of the drop=mgh =`1xx10^(-3)xx10xx10^(3)=10J` (b) Gain in KE of the drop=`(1)/(2)mv^(2)` `(1)/(2)xx1xx10^(-3)xx(50)^(2)` `=(1)/(2)=xx10^(-3)xx2500=1.250J` (c ) No, gain in KE is not equal to the loss in its PE, because a part of PE is utilised in doing work against the viscous drag of air. |
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