A steel rod 3 ft long with a cross-sectional area of 0.3 in.2 is stretched
between two fixed points. The tensile force in the rod is 1200 lb at 40F. Using a 1⁄4
6:5 106=
F and E 1⁄4 29 106 psi, calculate the temperature at which the stress in
the rod will be (a) 10 ksi; and (b) zero.