Introduction Of Chapter
Till now our analysis to simpler scenarios involving stiff bodies. A rigid body is a hard solid item with a clear shape and size and it cannot be deformed by applying external large forces.
But In actuality, bodies may be bent, crushed, and stretched when they are subjected to external forces. Even When a, steel bar is subjected to an external force that can be deformed. This implies that solid objects are not completely stiff. The deformation may be temporary of permanent depending on the magnitude of force and the elastic limit of the body. Hence there are two properties of a body to focus upon one is Elasticity and the other is Plasticity.
Elasticity is a property of a body that refers to the tendency of that body to return to its original size and shape when the external force is removed. Engineers must take into account the elastic behavior of materials like steel, concrete, etc. while designing and construction of bridges, cars, ropeways, etc.
However, if we apply force to a lump of putty or mud, they have no tendency to regain their previous shape, and they get permanently deformed. Such substances are called plastic and this property is called plasticity.
In this chapter, we shall study the elastic behavior and mechanical properties of solids which would answer many such questions like Why does a railway track have a particular shape like I or Why is glass brittle while brass is not ?