An iron rod(a=11.8x10-6 C-1) has a length of 1000 meters (or 1 km) at 0 degrees Celsius. If the rod must expand 10 cm to bridge a gap, to what temperature must the rod be heated?

Increase in L = a*(T-To)L = 10cm = 0.1m

11.8*10^-6/oC(T-0)1000 = 0.1
0.0118T = 0.1
T = 8.47o C