Thermal expansion is the change in size of an object as the temperature changes. Normally, as the temperature increases, the size of an object also increases. Conversely, the object will shrink as the temperature drops. Look at electrical power lines on a hot summer day. They will sag more than on a cold winter day. If you look at many bridges, they have interlocking metal fingers forming an expansion joint, where the bridge joins the road. This is to accommodate thermal expansion. (One notable exception to this general rule is water. It usually undergoes a normal thermal expansion, but as it approaches its freezing point, it will expand instead of shrink.) As an object expands or contracts with a temperature change, its change in length depends on three quantities: the original length, the temperature change, and the thermal properties of the material composing the object. Think...