20-mm diameter steel rod A=314.16 mm2 E=200 GPa α=12.0×10-6/∘C
Set the force-temperature-deformation relationship equal to zero and solve for ∆T.
δ=FLAE+α∆TL
∴∆T=-FαAE=-24,740 N(12.0×10-6/∘C)(314.16 mm2)(200,000 N/mm2) =-32.8 ∘C