1. The problem statement, all variables and given/known data A copper rod of length l_0 at 0 C is placed on a smooth surface.Now the rod is heated up to 100 C.FIND THE LONGITUDINAL STRAIN DEVELOPED ? 3. The attempt at a solution What I did : strain = delta l/ l_0 = l_0 alpha(coefficient of linear expansion) delta T/l_0 =100 alpha but surprisingly the answer is zero and the solution says since the "SURFACE IS SMOOTH". I have no clue why or how it works?