An electric heater is embedded in a long cylinder of diameter 30 mm. When water with a temperature of 25 deg C and velocity 1m/s flows over it the power per unit length required to maintain the surface at a uniform temperature of 90 deg C is 28 kW/m. When air, also at 25 deg C, flows over it at 10 m/s, the power required to maintain the same surface temperature is 400W/m. Calculate and compare the convection coefficients for the flow of water and air. [Hint: The water is flowing over the cylinder and therefore, heat transfer is through the surface of the cylinder, not the cross-sectional area. So you need to find the appropriate area per unit length]