An ordinary refrigerator is thermally equivalent to a box of corkboard 90 mm thick and 5.6`m^2` in inner surface area. When the door is closed, the inside wall is kept, on the average, `22.2^@C` below the temperature of the outside wall. If the motor of the refrigerator runs `15%` of the time while the door is closed, at what rate must heat be taken from the interior whicle the motor is running?
The thermal conductivity of corkboard is `k=0.05 W//mK`.