To develop this problem it is necessary to apply the concepts related to the uni-axial deflection of bodies.
From the expression of Hooke's law we have to
Where,
E= Young's modulus
The strain
And substituting P/A for stress and for strain gives that
Where,
P = Force
A = Area
L = Length
Therefore this can be re-arranged to give
If we want to calculate the deformation per unit area then we can also rewrite the equation as
Replacing with our values we have to
Therefore the posion ratio would be
Therefore the Poisson's ratio for this material is 0.4238