Question

The increase in length of a bar of length L, area A, modulus of elasticity E due to a tensile load P is given by

Answer 1

Use the formula,
$\bold{\text{Young's modulus }} =\bold{\frac{stress}{strain}}$
stress = Force/Area = F/A
strain = change in length/original length = ∆L/L
so, Young's modulus of elasticity = FL/A∆L
Here, Force ( tension ) = P, Area = A , Length = L
And Young's modulus = E ,
E = PL/A∆L
∆L = PL/AE

Hence, change in length or increase in length = PL/AE