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A 12 cm diameter cylindrical bar, initially at a uniform temperature of 40 degree Celsius, is placed in a medium at 650 degree Celsius with convective coefficient of 22 W/m2 K. Determine the time required for the center to reach 255 degree Celsius. For the material of the bar: Thermal conductivity = 20 W/m K Density = 580 kg/m3 Specific heat = 1050 J/kg K

A 12 cm diameter cylindrical bar, initially at a uniform temperature of 40 degree Celsius, is placed in a medium at 650 degree Celsius with convective coefficient of 22 W/m2 K. Determine the time required for the center to reach 255 degree Celsius. For the material of the bar: Thermal conductivity = 20 W/m K Density = 580 kg/m3 Specific heat = 1050 J/kg K Correct Answer 1973.16 seconds

1/B I = k/h R = 0.1515, t – t a/t I – t a = 0.647. X / l = 0 (center of the bar). Therefore, α T/R2 = 0.18.

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