A) 27 \[km{{s}^{-1}}\]
B) 550 \[km{{s}^{-1}}\]
C) zero
D) 129 \[km{{s}^{-1}}\]
Correct Answer: B
Solution :
Acceleration of rain drop. \[a=\left[ \frac{\rho -\sigma }{\rho } \right]g\] where \[\rho =\] density of water, \[\sigma =\] density of air. \[\therefore \] \[a=\left[ \frac{1000-1.2}{1000} \right]\times 10\] \[=9.98\,\,m{{s}^{-2}}\] Here, \[u=0\], and \[s=1200\,\,m\] Now, \[{{v}^{2}}={{u}^{2}}+2as\] \[\therefore \] \[{{v}^{2}}={{(0)}^{2}}+2\times 9.98\times 1200\] \[\Rightarrow \] \[v=154.7\,m{{s}^{-1}}=550\,km{{s}^{-1}}\]
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