Let’s see what happens to volume and weight as we increase the dimensions of a cube.

The weight of a growing cube increases at a faster rate than its dimensions. If each cubic centimeter weighs one gram, then Cube 1 weighs 1000 grams, Cube 2 weighs 8000 grams, and a third cube twice the size of Cube 2 would weigh 64,000 grams. Volume (and hence, weight!) increases faster than the dimension of a single side of the cube does.