question_answer 70)

                  Suppose the average mass of raindrops is \[3.0\times {{10}^{-5}}\,kg\]and their average terminal velocity \[9\,m\,{{s}^{-1}}\]. Calculate the energy transferred by rain to each square metre of the surface at a place which receives 100 cm of rain in a year.                

Answer:

                  Total mass, m = (volume x density) of water                 \[=(1\text{ }{{m}^{2}}\times 1m\times {{10}^{3}}kg/{{m}^{3}})\]                 \[={{10}^{3}}\,kg\]                 Energy transferred \[=K.E.=\,\frac{1}{2}\,m{{\upsilon }^{2}}\]                 \[=\frac{1}{2}\,\times {{10}^{3}}\times \,81=40.5\,\times \,{{10}^{3}}\,J\]                 \[=4.05\times {{10}^{4}}J\]