Total volume of rain drops, received 100 cm in a year by area 1 m2 =1 m2×100100 m=1 m3 As we know, density of water, d=103 kg/m3 Therefore, mass of this volume of water M=d×v=103×1=103 kg Average terminal velocity of rain drop v=9 m/s (given) Therefore, energy transferred by rain, E=21mv2=21×103×(9)2=21×103×81=4.05×104 J