Two cylindrical metal rods-one copper, the other lead-are connected in parallel with a temperature of 21.0°C at one end and 112°C at the other end. Both rods are 0.650 m in length, and the lead rod is 2.76 cm in diameter. If the combined rate of heat flow through the two rods is 33.2 J/s, what is the diameter of the copper rod?