Daer Rohini,

Properties of Elasticity & Plasticity:

1.) When a body is subjected to external forces such that there is no acceleration then the effect of these external forces would be to deform the body. The extent of deformation depends on the elastic properties of the body.

2.) Bodies which do not get deformed when subjected to external deforming forces are classified as ideal Rigid bodies which do not exist in reality.

3. a.) The rigid bodies which we see in our daily life are not ideally rigid.
b.) The behavior of solids, liquids and gases is different under the action of deforming forces.
4.) When the deforming forces are withdrawn, the body may regain its original shape and dimension. This is because of the restoring forces (internal forces) acting within the body, which oppose changes in the shape or dimensions of the body.

5.) The property of a matter by virtue of which it tends to regain its original size and shape after withdrawing the deforming forces is called elasticity. No material is perfectly elastic. Quartz can be taken as perfectly elastic body. (nearest example)

6.) The property of a matter by virtue of which it cannot regain its original shape or size after the withdrawal of deforming forces is called plasticity. The nearest example to a perfectly plastic body is putty. Chewing gum, wax, wet clay, lead solder, etc., are plastic bodies.

7.) Steel is more elastic than rubber. Water is more elastic than air. {in comparison }

8.) When a body regains its original size and shape completely after withdrawing the deforming forces, it is said a perfectly elastic body.

9.) If a body does not regain its original shape or size even after the removal of deforming forces, then it is said to be a plastic body (inelastic body).

10.) Almost all the bodies exhibit elastic nature up to some extent and later they exhibit plastic nature (degree of elasticities differ).

11). Decreasing order of elasticity of certain substances : Tungsten, Nickel, Steel, Iron, Copper, Phosphor bronze, German silver, Brass, Aluminum.

12.) With in the elastic limit, the restoring force setup within the body is exactly equal and opposite to the deforming force.

13.) Elasticity is the molecular property of matter.

14.) Within elastic limit every body behaves as an elastic body and beyond the elastic limit, the body undergoes some permanent change in shape or size and exhibits plastic behavior.

15.) The restoring force arising within the body increases as the deforming force on the body increases and opposes always in direction.

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