Elastic Behavior of Solids

You must have seen when you stretch a rubber band; it returns to its original form. Imagine taking an aluminum rod and bending it using your hands or arm strength. Will it be practically possible? Or does it regain its original position just like rubber? It might be confusing for some to understand the concept of elasticity when it comes to solids. 

This article about the elastic behavior of solids class 11 would talk about the properties and essential aspects of solids and how elasticity works in them. Along with that, it’d also cover the elastic and plastic behavior of solids. So, without any further ado, let’s get started! 

What does the elastic behavior of solids mean? 

Elasticity refers to the ability of a material to retain its original state instead of changing under stress. The distinguishing aspect of a material is its elasticity and plastic nature. In the above example of a rubber band, its high elasticity ensures that it doesn’t lose its shape permanently when stretched. However, every material has an elastic limit beyond which, if stress is applied, they will begin losing their elastic nature and ability to retain their shape and size. You need to understand that the elastic behavior of solids is bound to change after prolonged use, for instance, a hair tie. 

What is a solid?

A solid composes atoms and molecules closely arranged in a particular way wherein each molecule is acted upon by neighboring molecule’s forces known as intermolecular force. 

Elasticity of solids

The shape of the solid is specific due to the placement of the molecules and atoms. However, applying force would lead to the displacement of these molecules from fixed points. Once the force is removed, they regain their shape due to the interatomic and intermolecular forces, proving their elastic limit. As long as the elastic limit is not surpassed, the solid wouldn’t change permanently. 

Elastic limit is the maximum stress or force per unit area within a solid material that can arise before the onset of permanent deformation. 

Factors affecting the elasticity 

• Stress effect – When the solid gets exposed to a high number of stress cycles, it tends to lose its elastic characteristic. Therefore, the operating stress of the material should be lesser. 
• Temperature affects – The temperature largely affects the material’s elastic characteristics. At lower temperatures, the elasticity rises, and as the temperature increases, the elasticity falls. 
• Annealing effects – Annealing is a metal heating procedure where metal is heated at an extremely high temperature and then cooled down. This technique improves the ductility and softness of the metal. 

Mechanical properties:

There are three mechanical properties that explain the elastic behavior of solids. 

• Deformation: It refers to the change in the solid’s shape due to force or stress. 
• Deforming force: The outside force accountable for the change in the shape of the material. 
• Restoring force: The force that acts in the opposite direction to the deforming force and helps the solid in restoring its shape once the outside force is removed. For instance, the force used to stretch the rubber band is the deforming force, and the force that restores this elongated shape of the band to bring it back to the original position is the restoring force. 

• Plasticity: The inability of the material to return to its original shape and size, unlike an elastic body, even after removing the force, is known as plasticity. 
• Stress: It refers to the ratio of the internal force F, produced when the substance is deformed, to the area A over which this force acts. In a state of equilibrium, its formula is stress = F/A, where force is equal to the magnitude of the external force. 
• Strain: It is known as the ratio of the change in size or shape to the original size or shape. It doesn’t have any dimension. 

Chemical and Physical Properties of Solids 

• Solids are referred to as incompressible. It means that the constituent particles are kept close to one another, leading to a tiny amount of space between them. 
• Solids consist of a fixed volume, form, and mass, leading to a simple arrangement of the component particles. 
• Solids are not flexible. Since there is barely any space between the constituent particles, the solids become hard or even fixed. 
• The molecules consist of small intermolecular distances. Therefore, the force applied between the component particles, including molecules, atoms, and ions, is exceptionally strong. 
• When in the system, the particles can only fluctuate regarding their mean locations.
• The strength of the interactions between constituents determines the melting point of the solid. In case the interactions are solid, the melting point is generally high. 

Application of elastic behavior of solids:

• The rope used in cranes or lifts is based on the rope’s elastic limit and the weight it can carry. 
• The construction of bridges and pillars is dependent on the elasticity of the material and its strength. 

Key Points on the Elastic Behavior of Solids

• An elastic body can be defined as one that regains its original size and shape after the deforming forces are withdrawn. 
• A plastic body is referred to as a body that succumbs to deforming forces and does not return to its original size and shape. 
• Elasticity is the body’s property for regaining its original size and shape when the deforming forces are entirely removed. 

Conclusion 

In a nutshell, whether a solid can regain its shape and size after facing stress and pressure depends on its elastic behavior. Elastic behavior of solids depends on several factors, including deforming force, restoring force, strain and plasticity. These are all the properties and important aspects that one needs to keep in mind while dealing with the elastic behavior of solids.