When a stretching force (tensile force) is applied to an object, it will extend. This is because the extension of an object is not only dependent on the material but also on other factors like dimensions of the object e.g. length etc.
Stress is defined as the force per unit area of a material.
Stress = force / cross sectional area:
where,
σ = stress,
F = force applied, and
A= cross sectional area of the object.
Units of s : Nm-2 or Pa.
Stress = force / cross sectional area:
where,
σ = stress,
F = force applied, and
A= cross sectional area of the object.
Units of s : Nm-2 or Pa.
Strain is defined as extension per unit length.
Strain = extension / original length
where,
ε = strain,
lo = the original length
e = extension = (l-lo), and
l = stretched length
Strain has no units because it is a ratio of lengths.
Stress is proportional to Strain. The gradient of a graph of stress against strain is Young's Modulus (E).
Therefore...
Strain = extension / original length
where,
ε = strain,
lo = the original length
e = extension = (l-lo), and
l = stretched length
Strain has no units because it is a ratio of lengths.
Stress is proportional to Strain. The gradient of a graph of stress against strain is Young's Modulus (E).
Therefore...
Units of the Young modulus E: Nm-2 or Pa.
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