Aperson puts a few apples into the freezer at -15°c to cool them quickly for guests who are about to arrive. initially, the apples are at a uniform temperature of 20°c, and the heat transfer coefficient on the surfaces is 8 w/m^2c. treating the apples as 9-cm-diameter spheres and taking their properties to be ρ=840 kg/m3, k-0.418 w/m"c, α =1.3 x 10^-7 m^2/s, cp=3.81 kj/kg."c, determine the center temperature of the apples in 1 hour.