We will now take our system out of the vacuum and bring it closer to the real world. We will still assume that no heat comes from the end of the bar that is being heated and that we’ve still have good insulation wrapped around the bar (still no convection or radiation). We’ll now add convection to the radiating end of the bar. The coefficient of convection (for air) ranges from 0.0013 to 0.016 W/in2K, depending on the orientation. Since we are trying to heat our aluminum bar, we will assume the worst.