Question #adf2b

1 Answer
Mar 18, 2017

Linear expansion alpha is the length increase when an object is heated.
Volumetric expansion gamma is the volume increase.

Explanation:

If a block of material is heated, it will expand in all directions.

So in a block of 1mxx1mxx1m with a linear coefficient of alpha the volume increases from 1m^3 to (1+alpha)^3m^3 per degree.

Since alpha is very small (in the region of 10^(-5)//K), we can say that (1+alpha)^3~~1+3alpha with sufficient precision.

So the co-efficient of volumetric expansion: gamma~~3alpha

Note:
(1+alpha)^3=1+3alpha+3alpha^2+alpha^3 (Pascal)
Since alpha is very small (~~10^-5), alpha^2 will be in the region of 10^(-10) and alpha^3~~10^(-15).
These can be neglected, hece (1+alpha)^3~~1+3alpha

Note 2:
Of course, with liquids you can only measure volume expansion.