Chapter 4, Problem 174P

A potato may be approximated as a 5.7-cm-diameter solid sphere with the properties $p={\text{910 Kg/m}}^{\text{3}}\text{, }{c}_p\text{ = 4}\text{.25 kJ/kg}\text{.K , k = 0}\text{.68 W/m}\text{.K, }\alpha \text{ = 1}\text{.76 }\times {\text{ 10}}^{\text{-7}}{\text{ m}}^{\text{2}}\text{/s}$. Twelve such potatoes initially at 25°C are to be cooked by placing them in an oven maintained at 250°C with a heat transfer coefficient of 95 W/m² -K. The amount of heat transfer to the potatoes during a 30-mm period is

(a) 77kJ

(b) 483 kJ

(c) 927 kJ

(ci) 970 kJ

(e) 1012kJ