The 40-ft-long A-36 steel rails on a train track are laid with a small gap between them to allow for thermal expansion. Determine the required gap & so that the rails just touch one another when the temperature is increased from T_{1} = - 20 deg * F to T_{2} = 90 deg * F . Using this gap, what would be the axial force in the rails if the temperature were to rise to T_{3} = 110 deg * F The cross-sectional area of each rail is 5.1i * n ^ 2