Ten meter long steel railroad rails are laid end to end, with no space between, on a hot day when the temperature is 115°F. Six months later the temperature has dropped to -2°F.How much space now exists between each rail?

Answer 1

delta L/L = k delta T

delta L/L = 6.7*10^-6 inches/inch degree F (117 deg F)
L = 10 meters =394 inches
so
delta L = 394 * 6.7 *10^-6 * 117
= .309 inches = .784 cm = .0784 meters