The 40-ft-long A-36 steel rails on a train track are laid with a small gap between them to...

The 40-ft-long A-36 steel rails on a train track are laid with a small gap between them to allow tor thermal expansion. Determine the required gap S so that the rails just touch one another when the temperature is increased from T1 = - 20°F to T2 = 90°F. Using this gap, what would be the axial force in the rails the temperature were to rise to T3 = 110°F?The cross-sectional area of each rail is 5.10 in2.