On a rainy day, a friend of yours carefully observes the rain drop motion and proposes a rough estimate of 5 m/s for the terminal speed of the rain drop. Using your knowledge of fluid mechanics, make your own estimate of the terminal speed. You may assume an average rain drop to be a 0.002 m diameter (D) sphere. Density and dynamic viscosity of air are 1.184 kg / m ³ and 1.8 × 10 ^-5 N·s/m ² and the density of water is 999 kg/m ³ . Assume the drag coefficient can be approximated by that of a sphere, which can be found on the front page. The volume of a sphere is p D ³ /6.