Platonic solid the inradius "r". That is, The following table lists the various radii of the Platonic solids together with their surface area and volume. The overall size is fixed by taking the edge length, "a", to be equal to 2. The constants "φ" and "ξ" in the above are given by Among the Platonic solids, either the dodecahedron or the icosahedron may be seen as the best approximation to the sphere. The icosahedron has the largest number of faces and the largest dihedral angle, it hugs its inscribed sphere the most tightly, and its surface area to volume ratio is closest
Surface stress same, they are very different in solid–gas or solid–solid interface, which will be discussed in details later. Since both terms represent a force per unit length, they have been referred to as “surface tension”, which contributes further to the confusion in the literature. Definition of surface free energy is seemly the amount of reversible work formula_1 performed to create new area formula_2 of surface, expressed as: Gibbs was the first to define another surface quantity, different from formula_4, that is associated with the reversible work per unit area needed to elastically stretch a pre-existing surface. Surface stress can be derived