The handle of a ladle used for pouring molten lead at 328C is 30 cm

long. Originally the handle was made of 1.3 cm by 2.0 cm mild steel

bar stock. To reduce the grip temperature, it is proposed to form a

hollow handle of 1.5 mm thick mild steel tubing to the same rectangular

shape. The average heat-transfer coefficient over the handle surface is

17 W/m2K, when the ambient air temperature is 28C. The thermal

conductivity of mild steel is 43 W/m2K. Determine the reduction in the

temperature of the grip, stating the assumptions made.