Question

Putty or mud is an example of ?

Answer 1

Hint: Learn about mechanical properties of solids in a detailed manner. Study about the different types of rigid bodies and the basic differences between them to solve this problem.

Complete answer:
We know that there are four types of rigid bodies.
Perfectly rigid bodies: Perfectly rigid bodies are those when external forces are applied to the body the distances between the particles of the body is always fixed meaning with applying any amount of force the body cannot be bent or the volume or shape of the body cannot be changed.

Perfectly elastic bodies: This type of rigid bodies are those when external force is removed from the body the body goes back to its normal state means the volume and shape of the body changes to exactly the same when no forces are acting.

Perfectly plastic bodies: Perfectly plastic bodies are those when external forces are removed from the body the shape or size of the body remains deformed due to the application of the force.

Partly elastic bodies: Partly elastic bodies are those when external forces are removed the body changes to its original shape or size partly are called partly elastic bodies.Now, when force is applied to mud or putty the shape or size of it is deformed and after removing the force the body does not go back to its initial state. This property is only shown by perfectly plastic bodies as stated above.

Also, the measure of elasticity is measured in terms of different types of moduli of elasticity. Moduli of elasticity are nothing but the ratio of stress and strain applied to a body for different changes in dimension. There are three types of moduli of elasticity –Young’s Modulus, Shear Modulus and Bulk modulus. For mud or putty, the Young’s modulus or Longitudinal stress by strain is nearly zero so, mathematically they are proved to be nearly perfect plastic bodies.

Hence, putty or mud is an example of a perfectly plastic body.

Note: In real life there is no existence of perfectly rigid bodies. Since, all rigid bodies have some limit after which the shape or size of the body changes due to external force.Also, there is no perfectly elastic body, since after a certain limit the body cannot be changed back to its state. This limit of the body is called the elastic limit of the body and is different for different bodies.