A material of unknown composition with an initial length of 2.9 m is found to expand by 0.37 mm when it is heated by 15 K. What is the coefficient of thermal expansion of this material? K-1
(0.37 mm)/[(2900 mm)*15K] = 8.5*10^-6 K^-1
Note that the expansion amount and the original length have to have the same dimesions. I used millimeters.