Stress and strain

Stress: In mechanics, stress is defined as force applied per unit area. It is given by<nobr>
σ = F/A</nobr>
where, <nobr>σ</nobr><amp-mathml data-formula="\[ \sigma \]" inline="" layout="container"></amp-mathml> is the stress applied
F is the force applied
A is the area of force application
Stress is expressed as N/M².
Strain: The strain is the amount of deformation experienced by the body in the direction of force applied, divided by initial dimensions of the body. The relation for deformation in terms of length of a solid is given below.
<nobr>ϵ = δl/ L</nobr>
where, <nobr>ϵ</nobr><amp-mathml data-formula="\[ \epsilon \]" inline="" layout="container"></amp-mathml> is the strain due to stress applied
<nobr>δl</nobr><amp-mathml data-formula="\[ \delta \]" inline="" layout="container"></amp-mathml> is the change in length
L is the original length of the material.