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A long 10 cm × 20 cm rectangular cross section steel bar ݇ k= 63.9 W/mK...

A long 10 cm × 20 cm rectangular cross section steel bar ݇ k= 63.9 W/mK and alpha=18.8*10^-6 m^2 /s was heated to an initial temperature of 450°C. The steel bar is allowed to cool in a room with a temperature of 25°C and convection heat transfer coefficient of 25 W/m^2 K. The bottom surface of the bar is insulated while the other surfaces are exposed to convection. With a uniform nodal spacing of 5 cm, determine the duration required to cool the center of the bar to 100°C.

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