A cylindrical stone mix concrete beam of diameter D = 0.45 initially at Ti = 20C is exposed to hot gases at T(infinity) = 500C. The convection coefficient is h = 10 W/m^2K.
(a) Determine the centerline temperature of the beam after an exposure time of t = 5h.
(b) Determine the centerline temperature of a second beam that is of the same size and exposed to the same conditions as in part (a) but fabricated of ligthweight aggreate concrete with density p = 1495 kg/m^3, thermal coductivity k = 0.789 W/mK, and specific heat cp = 880 J/kgK.