A lead rod (a = 29x10-6 K-1) has a circular cross-section of 0.500 cm radius. The rod comes in a circular hole in a sheet of copper (a = 17x10-6 K-1) with a margin of 0.010 mm in its entire contour when both pieces are at 20°C.
a) At what temperature both pieces have zero margins?
b) Could this setting be possible with a lead sheet and a cooper rod? Why?