Aplane wall, 7.5 cm thick, generates heat internally at a rate of 105 w/m3. one side of the wall is insulated, and the other side is exposed to an environment at 90oc. (i. e. the fluid is at a temperature of 90oc.) the convection heat transfer coefficient between the wall and the environment is 500 w/(m2 k). if the thermal conductivity of the wall is 12 w/(m k), calculate the temperature in the center of the wall.