2.6. Consider a wire that undergoes an infinitesimal change from an initial equilibrium state to a final equilibrium state. (a) Show that the change of tension is equal to AY L d3aAYdT+ dL. (b) A nickel wire of cross-sectional area 0.0085 cm² under a tension of 20 N and a temperature of 20°C is stretched between two rigid supports 1 m apart. If the temperature is reduced to 8°C, what is the final tension? (Note: Assume that a and Y remain constant at the values of 1.33 x 10-5 K-1 and 2.1 x 106 Pa, respectively.)