A steel pipe of circular cross section that carries hot water is covered by a layer of insulating material, of thermal - conductivity ktayer = 0. 04 W/m K. The dimensions of the pipe are: mean radius Rpipe = 6 cm; total length of the pipe is Lpipe30 mi%3D The temperature of hot water inside the pipe is T water = 75 °c, the temperature of the surrounding air is Tair = 10 °C, while the Heat lost every hour through the lateral surface of the pipe is Qtost = 3 x 10° Joules/hour.Determine the thickness of the insulating material.