(a) A thermos flask is made up of two concentric cylinders of diameter 75 mm and 88 mm and length 250 mm. The space between the two cylinders is evacuated to reduce the heat loss. The outer surface of the inner cylinder and the inner surface of the outer cylinder are couted with silver paint. The emissivity of both the polished surfaces is 0.025. If the contents of the thermos flask are at 96 C and the ambient temperature is 27 C. calculate the heat loss from the flask. (b) If the space between the two cylinders is replaced by cork, what thickness of cork will be required to have the same heat loss as the vacuum condition. Thermal conductivity of cork = 0.042 W/mK. (The walls of the thermos flask can be assumed to be a flat plate).