Heat is a form of energy.
A light year is the distance traveled by light in a year.
Extraction of aluminium metal takes place in three main stages¿mining of bauxite ore, refining the ore to recover alumina and smelting alumina to produce aluminium. Bauxite is mined by surface methods (open-cut mining) in which the topsoil and overburden are removed by bulldozers and scrapers.
Line graphs can also be used to compare changes over the same period of time for more than one group. Bar graphs are used to compare things between different groups or to track changes over time.
