A long, square Nickel-Chrome alloy beam, 0.6 ft by 0.6 ft, is initially at 80°F. It is then hung in a heat treatment oven where the temperature is 1280°F and the total surface coefficient h = 8 Btu/hrft^2°F between the beam and the oven. The beam has a thermal diffusivity alpha equal to 0.20 ft^2/hr. After 1.8 hours have passed, find the lowest temperature in the beam. NOTE: A check has been made and the lumped parameter method CANNOT be used.