A body in equilibrium is one in which all the forces acting on it are balanced, resulting in a state of rest or uniform motion.
Elasticity is the ability of a material to deform under the influence of an external force and return to its original shape once the force is removed. This property is dependent on the material's composition and molecular structure.
Elasticity and fracture are closely related as a material's ability to withstand stress and return to its original shape without breaking is a measure of its elasticity. When a material is unable to withstand the applied stress, it undergoes fracture or breaking.
The elasticity of a material is affected by factors such as its composition, molecular structure, temperature, and the magnitude and duration of the external force applied.
Stress and strain are measures of the internal forces and deformation experienced by a body in equilibrium. When these forces are balanced, the body remains in equilibrium. However, when the forces are unbalanced, the body may undergo deformation, resulting in a state of non-equilibrium.