A plate of thickness 2L= 30 mm at a temperature of 600°C is removed from a hot pressing operation and must be cooled rapidly to achieve the required physical properties. The process engineer plans to use air jets to control the rate of cooling. The air jets are applied on both sides of the plate. The air supply is at 25 °C, and the convection coefficient on the surface is 400 W/(m2 ∙K). The thermophysical properties of the plate are rho=3000 kg/m3 , c=750 J/(kg∙K), and k=15 W/(m∙K)