Name: Introduction to Fluid Mechanics
Uploaded: 2019-07-19
Duration: 1 min 36 s
Description: A fluid can be at rest like water in a glass or in motion like water flowing in a pipe. This video explains fluid mechanics dealing with the behaviour of the...

Question

Define stress and strain.

Accepted Answer

When a force is applied, the size or shape or both may change due to the change in relative positions of atoms or molecules. This deformation may not be noticeable to our naked eyes but it exists in the material itself. When a body is subjected to such a deforming force, the internal force is developed in it, called as restoring force. The force per unit area is called stress.
$s t r e s s, σ = \frac{F o r c e}{A r e a} = \frac{F}{A}$

Strain measures how much an object is stretched or deformed when a force is applied. Strain deals with the fractional change in the size of the object, in other words, strain measures the degree of deformation. As an example, in one dimension, consider a rod of length l when it stretches to a new length $∆ l$ then $ε$ is a dimensionless quantity and has no unit.
$s t r a i n, ε = \frac{C h a n g e i n s i z e}{o r i g n a l s i z e} = \frac{∆ l}{l}$

Define stress and strain.

Important Questions on Properties of Matter

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