Explain spring ball model of elastic behaviour of solids.

Explanation

We know that in a solid each atom or molecule is surrounded by neighboring atoms or molecules.
These are bonded together by interatomic or intermolecular forces and stay in a stable equilibrium position.
When a solid is deformed, the atoms or molecules are displaced from their equilibrium positions causing a change in the interatomic distances.
When the deforming force is removed the interatomic forces tend to drive them back to their original positions and the body regains its original shape and size.
The restoring mechanism can be visualised by taking a model of spring-ball system as shown in figure. Here the balls represents atoms and spring represent interatomic forces. If you try to displace any ball from its equilibrium position, the spring system tries to restore the ball back to its original position.
Thus, elastic behaviour of solid can be explained in terms of microscopic nature of the solid.