Surface energy is the work per unit area done by the force that creates the new surface.
From the table, the surface energy is very large for Cast Iron, which is a brittle material that shatters without much warning. Since brittle fracture creates new surfaces, the surface energy varies inversely with the tendency to brittle failure. At high temperatures there is a tendency for glasses to change shape into a sphere. If the glass changes, from a cylinder of length 100 mm and diameter 20 m m, into a sphere, find the energy released. First find the radius of a sphere with the same volume as the cylinder.