Assume a slab that is 30 inches thickness and made of borosilicate glass at an average temperature of 32F is exposed to convective environment of surrounding air at 120F and h= 5Btu/h.ft2F. How long in hours will it take the average temperature to reach 90F ? Be sure to state which Equation(s) or Figure used in your calculations. You may assume that the surface temperature for this problem is the temperature of the air. The glass properties are: k=0.63Btu/h.ftF,cp=0.8Btu/lb.F, and =139lbm/ft3