A thermocouple junction is a spherical bead made of copper-constantan. The average thermophysical properties of copper-constantan are: k = 204 W/m-K, Cp = 402 J/kg-K, p = 8930 kg/m. Initially the junction has uniform temperature of 0 C and it is suddenly exposed to air flow at 100 C with the convection coefficient of 50 W/m-K. (a) If the junction diameter is 1.0 mm, how long will it take for the center of the junction reach 99.5 C? (b) Determine the instantaneous heat transfer rate at 5 seconds after the start of heating. (c) Estimate the total energy transferred from the sphere during first 2 minutes.