Consider some external force acting on a body, the force of resistance per unit area offered by a body against deformation is known as Stress. This external force which is acting on body is called the Load (or) Force. When the load is applied on the body while the stress is induced in the material of the body. The loaded body remains in equilibrium when the resistance offered by the body against deformation and the applied load are equal.
Stress is denoted by a letter "σ" (SIGMA)
Mathematically stress is written as σ = P/A
Where σ = Stress (or Intensity of stress)
P = External force (or) Load
A = Cross sectional area.
Units of Stress:
Units of stress depends upon two factors, they are units of Load and Units of area.
In MKS units, the force is expressed in kgf and area in square meters, so stress units are kgf/m^2.
In SI units, the force is expressed in Newtons and area in meter squares, hence units of stress becomes N/m^2.
In SI units, the force is expressed in Newtons and area in meter squares, hence units of stress becomes N/m^2.
