A cylindrical rod of PE (polyethylene), with a diameter of 0.02 m, at an initial uniform temperature of 150°C, is suddenly exposed to nitrogen medium at 25 °C for which the convective heat transfer coefficient has been found to be 132 W/m2⋅K. How long is it required for the surface temperature to decrease from150 °C to 40°C? What is the average temperature at that time? What is the centerline temperature at that time?