When a body is heated, its molecues vibrate faster and move further apart. As a result, the body expands. If the body is extreme in one dimension as compared to the other tow (a rod, for example, is much longer than it is high or wide) then we call it linear expansion. Otherwise it’s volume expansion. In both cases a coefficient of expansion is used to calculate the total expansion. These coefficients will be a property of the material. For solids, the volume coefficient is 3 times the linear coefficient.

The formula for linear expansion:

Where is the final length, is the initial length, is the coefficient of linear expansion, and is the temperature change. The formula for volume expansion follows a similar form: