The elasticity of a material is affected by the following factors:
(i) Effect of temperature: On heating, mostly the elasticity of materials decreases.
(ii) Effect of impurities: Depending upon the nature of impurity, the elasticity of materials may increase or decrease.
(iii) Annealing: Annealing decreases the elasticity of materials.
(iv) Hammering and rolling: This process increases the elasticity of materials.
Note: Annealing is a heat process where a metal is heated to a specific temperature /colour and then allowed to cool slowly. This softens the metal which means it can be cut and shaped more easily. Iron rod is heated till it turns red-hot.
Adhesive force is the attractive force between two unlike molecules. They are caused by forces acting between two substances like electrostatic force (attraction due to opposing charges), mechanical force etc.
E.g., Force of attraction between gum and paper.
Inter-atomic or inter-molecular forces are electrostatic in nature.