Heat energy per unit time \\\\(R = \\sigma AeT^4\\\\)Thus heat energy per unit area \\\\(R' = \\sigma e T^4\\\\)\\\\(\\implies\\\\) \\\\(\\dfrac{R'_2}{R'_1} = \\bigg( \\dfrac{T_2}{T_1} \\bigg)^4\\\\)Initial temperature of the body \\\\(T_1 =227 ^oC = (227+ 273) K = 500 K\\\\)Final temperature of the body \\\\(T_2 =727 ^oC = (727+ 273) K = 1000 K\\\\)\\\\(\ herefore\\\\) \\\\(\\dfrac{R'_2}{5} = \\bigg( \\dfrac{1000}{500} \\bigg)^4\\\\)\\\\(\\dfrac{R'_2}{5} = 16\\\\) \\\\(\\implies R'_2 = 80\\\\) \\\\(cal/cm^2\\\\)