In engineering, the modulus of elasticity is a way to measure how much an object deforms along an axis when opposing forces are
applied among that axis. The formula can be expressed as E=(F2−F1)L0(δ2−δ1)A , where E is the modulus of elasticity, F is the axial force, δ is a deformation measure, L0 is the original length of the object, and A is the cross-sectional area.
Consider an engineering material of initial length Lo, Area (A), Modulus of elasticity (E) and applied a force P due to which change in the length of the material is δ2 from it’s original length (Lo)
Initial length of the material is Lo. Hence, at time t = 0 when no force applied on the material the length of the material will not change (i.e., at time t=0, δ1 = 0)