A concrete wall 20m long and 3m wide with 10cm thickness with a thermal conductivity of 0.8W/mC is placed with an internal fiberglass sheet 4cm thick, with a thermal conductivity of 0.04W. /mC, covered by a 1mm thick sheet of wood, with a thermal conductivity of 0.12W/ mC, the internal and external ambient temperatures of the wall are 20C and 35C, respectively. The combined external convection and radiation coefficient is 40W/m2C, internally it has a fan which generates an air velocity of 1m/s and the wall surface temperature is 30C. Find the internal convection constant and the rate of heat loss from the wall.