it's one question

(a) Calculate the heat flux (in W/m2) through a sheet of a metal 13.0-mm thick if the temperatures at the two faces are 319 and 138 c. Assume steady-state heat flow and that the thermal conductivity of this metal is 53.8 W/m-K. W/m2 (b) What is the heat loss per hour if the area of the sheet is 0.477m?? 3/h a (c) What will be the heat loss per hour if a material with a thermal conductivity of 1.73 W/ mK is used? J/h (d) Calculate the heat loss per hour if the first metal is used and the thickness is increased to 225 mm. J/h Railroad tracks made of 1025 steel are to be laid during the time of year when the temperature averages 10C (50F). It a joint space of 4.50 mm (0.177 inches) is allowed between the standard 11.9 m (39-ft) long ralls, what is the hottest possible temperature that can be tolerated without the introduction of thermal stresses? "C