1. Triangular and parabolic straight fins are subjected to the same thermal conditions as the rectangular straight fin of Problem 3.134.
(a) Determine the length of a triangular fin of unit width and base thickness t = 3 mm that will provide the same fin heat rate as the straight rectangular fin. Determine the ratio of the mass of the triangular straight fin to that of the rectangular straight fin.
(b) Repeat part (a) for a parabolic straight fin.
2. Two long copper rods of diameter D = 10 mm are sol- dered together end to end, with solder having a melt- ing point of 650°C. The rods are in air at 25°C with a convection coefficient of 10 W/m2 · K. What is the minimum power input needed to effect the soldering?