The Golden Gate Bridge in San Francisco has a main span of length 1.28 km, one of the longest in the world. Imagine that a steel wire with this length and a cross-sectional area of 3.40 10^-6 m2 is laid on the bridge deck with its ends attached to the towers of the bridge, on a summer day the temperature of the wire is 36.0°C.
(a) When winter arrives, the towers stay the same distance apart and the bridge deck keeps the same shape as its expansion joints open. When the temperature drops to ?10.0°C, what is the tension in the wire? Take Young's modulus for steel to be 2.00 *10^11 N/m2. (The average linear expansion coefficient for steel is 1.1*10^-5° C^?1.)
(b) Permanent deformation occurs if the stress in the steel exceeds its elastic limit of 3.00*10^8 N/m2. At what temperature would the wire reach its elastic limit?