A steel rod 10 m long is at a temperature of 200C. The rod is heated to a temperature of 600C. What is the stress induced in the rod if it is allowed to expand by 4mm, when E = 200 GPa and α = 12 x 10-6/0C?
(a) 64 MPa (b) 48 MPa
(c) 32 MPa (d) 16 MPa